Carcinogens are chemicals or other hazards that can cause, promote or increase the risks of cancer. They have traditionally been regarded as substances that damage DNA directly or through the formation of oxidising free radicals causing rearrangements and mutations of the genes. In this case, the genes that cause cancer (Oncogenes), get separated from the genes that stop them activating (suppressor genes) and placed next to genes that stimulate them (promoter genes). The activation and promotion of these genes then trigger harmful biochemical pathways leading to cancer. Carcinogens, however, also have other complex direct and indirect modes of actions which affect the risk of cancer development and promotion. In summary, the mechanism of action of carcinogens in include:
- Genetic damage
- Via free radicals that directly damage DNA
- Inhibit DNA repair
- Alter expression of genes (epigenetics)
- Reduce immunity
- Promote chronic inflammation
- Stimulating hormone sensitive cells
The World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to carcinogen exposures is between 7% and 19%. This number is likely to be higher as we are exposed to a substantial number of chemicals, on a daily basis, and for long periods of our lives and only about 50% of chemicals have undergone even minimal testing for carcinogenicity by the Environmental Protection Agency (EPA). We are exposed to a wide array of these potential dietary and environmental chemicals but many are completely safe, others are known to be definitely carcinogenic, others are have uncertain potential or are under investigation. IARC categorises them into five groups
- Group 1: Carcinogenic to humans
- Group 2a: Probably carcinogenic to humans
- Group 2b: Possibly carcinogenic to humans
- Group 3: Unclassifiable as to carcinogenicity risk
- Group 4: Probably not carcinogenic to humans
The EPA, part of the American Food and Drug Administration (FDA) and similar organisations internationally are responsible for detecting and regulating carcinogens in our environment and food chain. They test for their ability to cause cancer using cultured cells in the laboratory and in animals looking for the degree of carcinogenicity, based on four criteria; gene mutation; clastogenicity; DNA damage and cell transformation. They then share their data with other countries in accord with the Cooperative Research and Development Agreement (CRADA).
Why do carcinogens matter after a cancer diagnosis?
Although patients with established cancer have already sustained the initial DNA damage in order to mutate from benign to malignant cells, the progress from an early cancer to one that has spread around the body can be fuelled by continued consumption of carcinogenic foods. Further DNA damage encourages the cancer to mutate into a more aggressive type or develop mechanism to hide from the body’s immunity or become resistant to medical treatments. Carcinogens can also have a direct effect on the biological processes that cause cancers to become more harmful via a number of mechanisms, which encourage cancer cells to:
- Grow faster (proliferate)
- Not die when they have reached the end of their life cycle (apoptosis),
- Stimulate blood vessels to feed the rapidly growing cells (angiogenesis),
- Loose their stickiness to the site of origin (loss of adhesion),
- Grow into adjacent organs (invasion)
- Spread through the body (metastasise).
Avoiding carcinogens after cancer is also a benefit by reducing the risk of developing further new cancers that are more likely in patients who have a greater susceptibility from a pre-existing genetic vulnerability or acquired genetic damage from chemotherapy or radiotherapy. This hypothesis is supported by a study from Newfoundland, which evaluated the eating habits of 529 patients with colorectal cancer. They found that between the highest and lowest quartile of processed meat intake there was a two-fold increase in relapse and overall death rate. The carcinogens within processed meat particularly those smoked, fried or high-temperature cooked include N-nitroso compounds, heterocyclic amines and polycylic aromatic hydrocarbons and the mechanisms of harm are explained later. Other trials have demonstrated an association between dietary carcinogens and relapse for ovarian cancer and breast cancer.
The effect of diet on individuals more susceptible to cancer was demonstrated by a study conducted by the Radiation Effects Research Foundation (RERF) involving people surviving the Hiroshima and Nagasaki bombings. They showed that those who undertook regular exercise and had a higher intake of fruit and vegetables and had a low meat intake had a significantly lower risk of cancers despite their acquired susceptibility. Furthermore, a study evaluating the eating habits of 486 people with the genetic susceptibility Lynch syndrome showed that diets that featured a major unhealthy snack component – chips, fast food and sweets – had an increased risk of developing colorectal adenomas. Likewise, lifestyle habits were significant factors in the development of breast disease in women presenting at a young age who had strong family histories.
How much of a carcinogen exposure is harmful?
It is impossible to live a life free of carcinogens, which is also unnecessary as the body’s natural anti-oxidant defences are able to cope with a certain amount. It’s only when excess levels are consumed over long periods of time that these defences can be overloaded. The harmful effect of carcinogens, very much depends on the amount taken over time and whether they are consumed with other carcinogens (total carcinogenic load) or combined with natural anticancer phytochemicals. A good example is coffee, which contains moderate levels of acrylamide (a probable carcinogen) but is also loaded with healthy polyphenols – the net result is that studies show that regular coffee intake is associated with a lower risk of cancer. Likewise, a study from Maryland, USA eloquently demonstrated that levels of the carcinogen in barbequed meat known as polycyclic hydrocarbons is significantly lower if it had been marinated in polyphenol-rich rosemary and eaten with a salad.
So the risk of a carcinogen depends on other dietary or environmental factors which may enhance or negate and the underlying susceptibility of the individual exposed. Nevertheless, for ease of explanation, this section tries to quantify levels and provided advice on how to avoid them within separate categories separately although of course there are considerable crossover and synergy effects between them.
Natural antidotes to carcinogens: As well as avoiding carcinogens it is important to concentrate on lifestyle strategies which prevent cancer either on their own or by acting as antidotes to carcinogens. These are addressed in their own sections and include regular exercise; having a healthy profile of gut bacteria, adopting an anti-inflammatory lifestyle; ensuring good levels of vitamins and minerals and ensuring a high intake of polyphenol rich foods.
Categorisation of carcinogens
- Dietary carcinogens
- Pesticides and herbicides
- Infective agents
- Naturally occurring exposures (ultraviolet light, cosmic radiation and radon gas)
- Medical treatments (radiation, chemotherapy, hormone drugs, immune suppressants)
- Electromagnetic waves
- Industrial and environmental exposures
Lifestyle factors such as smoking, sedentary behaviour, alcohol, obesity, sun burning exposure and processed sugar intake although increasing the risk of cancer are not usually classified as carcinogens and are described separately in other lifestyle habit sections.
What, how much and when we eat has a considerable influence on the development and progression of cancer. Unhealthy choices can lead to overeating, high processes sugars and bad fat intake and deficiencies in vitamins, minerals and polyphenols. These issues are covered in their own sections in this book but this section addresses itself with specific groups of chemicals fund naturally in certain foods, added during its growth, formulation or generated in cooking process that may have direct carcinogenic properties. Many of these are related to high temperature, frying or baking of carbohydrates, sugars, fats and meats. The most common dietary carcinogens are:
- Heterocyclic amines (HCAs)
- Polycyclic aromatic hydrocarbons (PAHs)
- N-nitroso compounds (Nitrosamines)
- Pesticides and herbicides
Acrylamides are not deliberately added to foods, they are natural by-product of the cooking process. They are chemical substances formed by an interaction between amino acids (mainly asparagine) and sugars in a process called the Maillard Reaction. Acrylamides are typically formed when foods with high sugar and starch content are cooked at high temperatures (over 120°C) in a process of frying, grilling, roasting or baking for three minutes or longer. This chemical process ‘browns’ food and affects its taste so within moderation is an advantage to the cooking process and if not consumed in excess are unlikely to be harmful. The problem lies if the ingredients and cooking process results in very high acrylamide concentrations.
Following ingestion, acrylamides are absorbed from the gastrointestinal tract, distributed to all organs and extensively metabolized into glycidamide. Laboratory animals orally exposed to acrylamide and glycidamide have an increased likelihood of developing gene mutations and cancers. High acrylamide exposure to animals also lead to harmful effects on the nervous system including muscle weakness, paralysis and adverse affects on male reproduction. Researchers at the Swedish National Food Administration and Stockholm University first reported acrylamides in foods consumed by humans in 2002. Despite the adverse effects on animals, epidemiological studies in humans linking their intake with cancer are inconclusive, that is why they are classed, by the Food and drug administration (FDA) as probable carcinogens. Many scientists agree, however, that acrylamides in food have the potential to cause cancer in humans as well and it would be prudent to reduce exposure.
Sources of dietary acrylamides
Think of foods which are high in sugar or starch carbohydrates that have been heated to high temperatures and you have the leading contenders such as fried potato products, biscuits, crackers, and crisp bread. In response to the public concerns the USA Food and Drug Administration (FDA) began to analyse a variety of U.S. food products for acrylamide (AA) concentrations and now publish regular league tables. There are also now moves to legislate the introduction of AA labelling on food products. This is however, proving difficult because the levels of AA depends not only on the foods we buy but on the individual cooking processes, whether cooked at home or from one outlet to another. Cooking processes, for example, which add sugar or honey prior to cooking ramp up the acrylamide content, which explains why in the table below similar foods have vastly different levels. A good example is plain crisps have four times less the AA contents as ‘Sweet Chili Kettle crisps” which not only have sugar added to the potato they have a sweet flavouring sprinkled on top before deep frying. Likewise, the cooking process itself alters the AA content for the exactly the same foods. Gently toasting bread or cakes has significantly lower AA than over baked almost black cakes or burnt toast, which should be avoided. Baking potato snacks are often described a healthy because they contain more fat. Interestingly, baking potatoes at high temperatures may be one of the worse ways to cook them. For instance, according to the 2006 FDA’s data on brand of regular fried chips contained only 110 ppb but its baked version ten times higher at 1000 ppb. It must also be remembered that total ingested AA is more important than the concentration in each foods; a small quantity of a food with high levels of AA such as a cream cracker is still safer than a large quantity of food with lower concentrations such as a bag of potato crisps.
|Potentially > 4000 ppb
Malt extract drinks
Sweet potato crisp (chips)
Veggie chips potato snacks
|Often 2000-4000 ppb
Sweet chilli standard potato crisps
Roasted oat bran crackers
Kettle crisps (with added sugar)
Baked breakfast cereals
|Often 500-2000 pbb
Bruschetta vegetable crackers
Grahams crackers or Ginger snaps
Flavoured tortilla corn chips
Rye crisp-bread sesame
|Usually < 500 pbb
Plain tortilla cord chips
Butter flavoured popcorn
Dark roast coffee
|Usually <50 pbb
Light roast coffee
Bread – not toasted
Advice to reduce levels of dietary acrylamides:
You can accomplish a low dietary input by limiting French fries, chips, baked cereal or potato products, cookies, pastries, biscuits and pies, which tend to have the most acrylamides. Be particularly weary of cooked product sold as healthy because they are low fat such as baked cereal or potato snack – often found in the health food sections on shops. Likewise, avoid products with added sugar or sweeten flavors before cooking. Look on the label, some breads and crisps to not have added sugar but many do. Kettle crisps or many brands of heavily flavored regular chips or potato snacks often have added sugar – read the label and avoid. Storing raw potatoes in the fridge may lead to the formation of more free sugars in the potatoes (a process sometimes referred to as ‘cold sweetening’) and can increase overall acrylamide levels especially if the potatoes are then fried, roasted or baked. If you want to fry or roast potatoes do so only until they are golden yellow, not browned or blackened. When baking, again avoid over browning or burnt cakes. The same goes for toasting your bread – don’t char or burn it. And if you’re a coffee drinker, you might want to opt for lightly roasted coffee beans in place of darker ones. There’s no reason to give up breakfast cereals, but do choose ones made from whole grains and are not heated to high temperatures with added sugar. Instead of these foods try increase intake of fruit and raw vegetables, which not only are low in AA but contain polyphenols, the natural antidotes to carcinogens. So in summary:
- Limit intake of kettle chips, cereal bars, baked potato snack products and French fries.
- Limit intake of cookies, pastries, biscuits and dry crackers
- Avoid foods with added sugar that are then baked at high temperatures or fried.
- Eat fresh rather than roasted nuts
- Try eating as many raw (healthy) fruit and vegetables food as feasible
- If high AA content foods eat them with polyphenol rich foods – the natural antidotes
- Eat whole prunes rather than prune juice
- Don’t store potatoes in the fridge
- Try not to over bake food – go for a golden yellow colour or lighter rather than brown
- When frying or grilling avoid charring the foods
- Cut the blackened over charred foods pieces off before eating
- Refrain from eating burnt toast
- Don’t over roast starchy foods like potatoes, root vegetables and bread
Polycyclic aromatic hydrocarbons (PAH) and hetero-cyclic amines (HCA)
Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are chemicals formed when muscle meat, including beef, pork or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame. More specifically HCAs are formed when amino acids (the building blocks of proteins), sugars, and creatine (a substance found in muscle) react at high temperatures. PAHs are formed when fat and juices from meat grilled directly over an open fire drip onto the fire, causing flames. These PAH containing flames then adhere to the surface of the meat. PAHs can also be formed during other food preparation processes, such as smoking of meats. The formation of HCAs and PAHs varies by meat type and more likely occur when cooking at high temperatures, especially above 300ºF (such as grilling or frying). For example, well done, grilled, or barbecued chicken and steak all have high concentrations of HCAs. Cooking methods that expose meat to smoke or charring also contribute to PAH formation.
What’s the evidence that HCAs and PAHs increase cancer risk?
HCAs and PAHs are carcinogenic because they are capable of DNA damaging DNA causing mutations. In laboratory animal experiments, high intake have been shown increase the risk of cancer of the breast, colon, liver, skin, lung, prostate and other organs. The risks for human have been estimated via dietary questionnaires within epidemiologic studies which have clearly found a link between high consumption of well done, fried, charred, smoked or barbecued meats with increased risks of colorectal, pancreatic and prostate cancer.
These studies show a considerable variation in humans. This may be that questionnaires do not capture all the details about cooking techniques and types of meat so may overestimate intake in some people and underestimate in others. Questionnaires may, also, not be sensitive enough to pick up food combinations such as regular intake together with the polyphenol rich foods (natural antidotes), which reduce the risk, or meals usually combined with carcinogenic rich foods which would enhance the risk. Furthermore, HCAs and PAHs only become capable of damaging DNA after they have been metabolised by specific enzymes in the body, a process called bioactivation. It is known that the activity of these enzymes can differ from one person to another so some people are lucky enough to be inherently more resistant to these carcinogens and some are more sensitive. Finally, questionnaire may not pick up other PAH exposure from other environmental sources, such as car exhaust fumes other smoke pollution and tobacco smoke.
Advice to reduce HCA and PAH formation in cooked meats?
In terms of cancer risk there is no reason to cut meat completely from your diet but Cancer Council does recommend avoiding cheap processed meats such as sausages, bacon, ham, pies and salamis or meats which have been smoked. They also suggest eating only moderate amounts of red meat a week up to three times a week but instead consider using beans, lentils, quinoa, fish or even chicken. On top of this, attention to cooking methods can further reduce HCA and PAH consumption:
- Avoiding direct exposure of meat to an open flame or a hot metal surface
- Avoiding prolonged cooking times (especially at high temperatures).
- Use an oven to partially cook meat prior to grilling or barbecuing.
- Continuously turn or flip meat over on a high heat source.
- Clean to frying pan, griddle, hot plate or barbeque from the blackened remains
- Remove charred portions of meat
- Refraining from using gravy made from meat dripping
N- Nitroso compounds
Nitrates and nitrites are two types of inorganic compounds, which compose of a single nitrogen atom (N) and a number of oxygen atoms (O); and the chemical symbols are NO3 and NO2 for nitrate and nitrite, respectively. They are both found naturally in many healthy foods and are added to processed meats as preservatives. It is believed that nitrates themselves are relatively inert, until they are reduced to nitrites. Nitrates can turn into nitrites by bacteria in the mouth and then be swallowed. There is a lot of confusion about the risks and benefits of nitrates or nitrites, which in themselves are not carcinogens. Nitrites can only be poisonous if consumed in huge quantities and in this case a condition called methemoglobinemia occurs in which the nitrite deactivates hemoglobin stopping it carrying oxygen. There have been some rare reports in infants drinking water contaminated nitrate fertilisers. After consumption, depending how they are eaten, the environment they are digested and what they are eaten with they are either convert them into nitric oxide, which has numerous healthy benefits, or volatile nitrosamines such as nitrosodimethylamine (NDMA), which is carcinogenic. In the laboratory most nitrosamines can induce animal carcinogenesis by causing gene mutation and DNA adductions which is why they have been shown to inducing malignant tumors in various animal species in a variety of tissues, including liver, lung, and stomach. In man, studies suggested they could be implicated in the risk of both childhood and adult brain tumors. Multiple epidemiological studies have found a relationship between processed meat intake and increased risk of colorectal cancer. In 2018, an analysis of the massive UK biobank study involving 262,195 women found that just processed meat intake equivalent to 2 sausages a week was linked to an increased risk of breast cancer. The WHO and WCRF have issued repeated warnings that nitrite rich processed meats are definite carcinogens.
Sources of nitrates or nitrites: In a typical person’s diet, 80 percent of nitrates come from vegetables such as beetroot, spinach, radishes and lettuce. The rest comes from the preservative sodium nitrite, which helps fights harmful bacteria in bacon, ham, salami and other processed and cured meats and also lends them their pink coloration. Other sources include some cheeses, nonfat dry milk, cured dried fish, cigarette smoke and some cosmetics. Beer contain some nitrites but as it can be drunk in large quantities the overall intake of nitrates can be high especially if accompanied with a plate of salami and dried ham with no vegetables – habits quite familiar to many beer drinkers.
What factors influence the conversion of nitrites into carcinogens? In some heavily processed meat the nitrites have already been converted in to the volatile nitrosamine called nitrosodimethylamine (NDMA) as a result of direct-fire drying. Likewise dried, smoked and salted fish have also been found to contain high concentrations of nitrosamines and not surprisingly their regular intake has been associated with higher rates of colon and rectal cancers. Grilling or frying amino acid rich meats at high temperatures can also encourage the conversion of nitrites to nitrosamines. On the other hand, even though vegetables contain nitrates/nitrites, they are rarely exposed to such high heat and are low in amino acids so don’t contain NDMA. Within the body the bacteria in the stomach and gut, the heme ion in red meat, the amount of vitamin c and healthy polyphenols can all affect whether either carcinogenic nitrosamines or healthy nitric oxides are formed.
Bacterial overgrowth in the stomach, particularly helicobacter pylori can create an environment conducive for nitrosamine formation, which may explain why chronic infection with this bacteria increases the risk of stomach cancer. People who use proton pump inhibitors, a common class of acid suppressants, may also be more susceptible to nitrites because the diminished acidity in their stomachs encourages bacterial growth. On the other hand, a healthy bacterial flora in the rest of gut reduces the formation of nitrosamines and generally reduces inflammation protecting the mucosa. Ascorbic acid (vitamin C), chlorophil and other polyphenols in foods also directly inhibits nitrosamine formation in foods. This explains why vegetables high in nitrates/nitrites do not increase the cancer risk, in fact quite the opposite; they are associated with a lower cancer risk and have numerous healthy benefits. In an effort to minimize nitrosamine formation, while still preventing food-borne infections, meat manufacturers now add the antioxidant ascorbic acid, or vitamin C, to their products. The heme ion in red meat has a catalytic effect on formation of nitrosamines from nitrites. This explains the findings from epidemiological studies reporting a link between red and processed meats and bowel cancer but not with white meats consumption. The heme ion also has other direct carcinogenic properties via the creation of cytotoxic and genotoxic aldehydes caused by lipoperoxidation of unhealthy fats. This explains the induction of colon cancer finding in laboratory rats feed with dietary hemoglobin and red meat even without nitrites.
Benefits of plant nitrates Plant nitrates provide a natural means of increasing blood nitric oxide (NO). Many vegetables contain nitrates but the most notable include:
- Argula lettuce
- Spinach and kale
- Rocket salad and water cress leafs
- Celery and radish
The mechanism for the production of NO starts with the microflora in the upper gut which convert nitrates to nitrites which are then metabolised to NO and other nitrogen oxides by a variety of reductase enzymes. This process is further enhanced by vitamin C which also prevents its’ conversion to nitrosamines. Pathologies associated with diminished NO bioavailability, such as those associated with abnormal endothelial function, including hypertension, atherosclerosis, type 2 diabetes and dementia. NO is absorbed by endothelial cells lining the arteries, then penetrates the underlying smooth muscles and acts as a potent vasodilator that relaxes the arteries. Therefore, NO plays a critical role in controlling blood pressure and improving overall circulation including a better oxygenation of the heart , muscles and brain during exercise. Studies in humans have demonstrated that the NO generating properties of nitrate rich foods are likely to be responsible for improvements in cerebrovascular blood flow, improved erectile function and lower cognitive deficits. Other studies have evaluated neutraceutical concentrating nitrate rich foods such as beetroot as a means of enhancing athletic performance via improved muscle blood flow and absorption of free radicals produced by strenuous exercise. As these foods are also rich in polyphenols they also have general anticancer, anti-inflammatory and anti-arthritis benefits.
Advice Do not reduce nitrate rich vegetables, these are healthy. Instead avoid meals which contain nitrites heavy meats without the measures to prevent them being in carcinogenic either in the cooking process or body:
- Avoid hot dogs, sausage, ham, bacon, pastrami, salami and tinned luncheon meats.
- It you like cured meats go for good quality whole muscle meats
- Serrano ham has low nitrites, biltong, Parma ham & prosciutto don’t have added nitrites.
- Avoid foods already containing nitrosamines direct-fire drying meats, dried salted fish
- Reduce the heat when grilling or frying
- If you are a meat eater reduce intake of heme ion rich red meats (beef, lamb or liver)
- Eat vitamin C and polyphenol rich veg with every meal especially if it includes meat.
- Avoid taking long term anti-indigestion therapies if possible – see tips to prevent indigestion
- Look after your healthy gut bacteria – see tips for healthy gut
Pesticides and herbicides and other farming contaminants
Pesticides are a group of chemicals used for the destruction of insects, weeds, fungi and bacteria. They are generally called insecticides, fungicides, bactericides, herbicides or rodenticides. Pesticide residues may constitute a significant source of contamination of environmental factors such as air, water and soil. A number of studies reported that pesticides have been shown to accumulates in wildlife and farmed animals. This could become a continuous threat to the co-existence of plant and animal communities of the ecosystem. On the other hand, problems caused by pest lead to loss of about one third of the world’s agricultural production every year, and without pesticides man would not be able to feed itself. Categories of pesticides include the organochlorines, creosote and sulfalate, which have mutagenic properties and DDT, chlordane, and lindane which are tumour promoters. Arsenic compounds in insecticides used on farms and gardens have also been classified as carcinogens by the International Agency for Research on Cancer. The fungicide benomyl is classified as possible human carcinogens as it disrupts the microtubules cell division leading to altered growth. Chlorothalonil, a broad-spectrum fungicide that is used on vegetables, fruit trees and agricultural crops, is considered to be non-genotoxic but classified as ‘likely’ to be a human carcinogen as it reacts with proteins, decreasing cell viability. In cell line studies, lindane promotes induces tumour formation by disrupting the normal apoptosis pathway when cells are damaged leading to damaged cells proliferating. MXC is a DDT derivative that was developed after the ban of DDT and it exhibits anti-androgenic and estrogenic activity. MXC also stimulates proliferation and human breast cancer cell growth by the up-regulation of genes, through oestrogen receptor signalling, leading to promotion of tumour angiogenesis. As well as the active ingredients themselves, some contaminants in commercial pesticide formulations may also pose a carcinogenic risk.
Although many studies have shown that pesticides accumulate in humans as well as plants and animals, there is conflicting evidence that have a negative physiological impact or increase cancer risk. Some epidemiologic studies have linked exposure to phenoxy acid herbicides or contaminants in them, with soft tissue sarcoma and malignant lymphoma. Organochlorine insecticides have been linked with sarcoma, non-Hodgkin’s lymphoma (NHL), leukaemia, and, less consistently, with cancers of the lung and breast. Organophosphorus compounds have been linked with NHL and leukaemia and triazine herbicides with ovarian cancer. Research, published in the Lancet in 2005, have found that people with high levels of organochlorines pesticides in their blood stream were far more likely to develop genetic mutations in a gene called K-Ras which is linked with a higher risk of cancer of the pancreas. In support of this finding, K-Ras genes have been found to be targets for chemical carcinogens in laboratory studies of animals and this correlates with a more aggressive type of cancer. Another study, published in the Journal of Clinical Oncology in 2010, looked at the blood levels and history of exposure to a carcinogen called Chlordecone (Kepone) in 623 men with prostate cancer and compared them to levels in men without cancer. The levels of carcinogens were significantly higher in the cancer group, indicating that they were a likely contributor to the illness. The risk was particularly high if men already had a genetic susceptibility to prostate cancer as measured by an analysis of their DNA. Chlordecone was an organochloride insecticide with both mutagenic and xenoestrogenic properties used extensively between 1973 and 1993 in the West Indies to control banana root disease. So hopefully it is no longer in the food chain unless used illegally.
Advice to reduce pesticide and herbicide exposure: One of the best ways to reduce absorption of pesticides and herbicides is to buy organic food where feasible. The term “organic” refers to both the method of growing and the processing foods. Organic agriculture involves avoiding use of synthetic fertilizers and pesticides. But instead use holistic methods of weed control and deterring crop disease such as long crop rotations, using predator insects or insect traps all of which providing habitat variety that supports animal welfare, storage of more carbon in permanent grassland, recycling of nutrients and more biodiversity. There is robust evidence, from robust studies that organic foods provide more healthy phytochemicals and less pesticides and herbicides. Most notably, a group at Newcastle University, in 2014 analysed 343 studies to look at any differences between organic and conventional crops. They found that a switch to eating organic fruit, vegetable and cereals would provide additional blood phytochemical levels equivalent to eating 1-2 extra portions of fruit and vegetables a day. In addition, they found significantly lower blood levels of pesticides and heavy metals in consumers of organic foods versus conventionally grown ones. Likewise, scientists at Stanford University performed a large clinical review, including over 200 clinical trials, concluding that an organic diet reduces exposures to pesticides, antibiotic-resistant bacteria and nitrates.
Organic food cannot be completely free of synthetic chemical residues due to some allowed product and environmental pollution. Likewise, some foods are naturally grown organically such as nuts and many olives but because the farmer has not applied for a certificate but are still naturally low in man-made chemicals. Moreover, for a meal to have an organic certificate it must also avoid genetically modified organisms (GMO) ingredients, not have added artificial preservatives, artificial sweeteners, colourings, flavourings, hydrogenated fats or monosodium glutamate which is an attractive feature for many health aficionados. Despite the nutritional benefits of organic foods further research is required to establish whether long-term regular intake would improve health and reduce cancer risks. In the mean time, as it is completely impractical to restrict your diet to organic food or avoid pesticides in other ways it’s a case of reducing your exposure by buying organic were you can considering these other tips:
- Consider growing your own fruit and veg in your garden, allotment or even windowsill
- Buy a good salad spinner
- Soak lettuce leaves and herbs in water, thoroughly then spin them dry before eating
- Wash fruit before put them onto the fruit bowel.
- Wash vegetables first and change the water before cooking.
- Buy organic food where possible
- Rinse plates with detergent free water before drying
Non Dietary Carcinogens
The most ubiquitous infection is the Human Papilloma Virus (HPV) that can cause skin warts but also significantly contributes to the risk cervical and head and neck cancer, transmitted via sexual activities. Human T-cell lymphotropic virus type I (HTLV-1) later became known as Human immunodeficiency virus (HIV) causes Acquired Immune Deficiency Syndrome (AIDS) that reduces the ability to flight both infection and cancer. Kaposi sarcoma herpes virus (KSHV), also known as human herpes virus 8, can cause a rare skin cancer especially in immune deficient people. Chronic infection with Hepatitis B virus Hepatitis C virus is a major cause of liver cancer across the world. A virus found in Africa called the Ebstein-Barr virus causes an aggressive form of cancer of the lymph nodes called Burkitt’s Lymphoma. Merkel Cell Polyomavirus (MCPyV) is linked to a rare type of skin cancer. The bacteria, helicobacter pylori, infects the stomach causing gastritis, indigestion and over time an increased risk of stomach cancer. There are reports of an increased risk of bowel cancer in people who have previously had severe salmonella food poisoning although this may be an association rather than cause. In summary the most well known cancer promoting infections include:
- HPV – Cervix & Head and neck cancers
- HIV – AIDS – Lymphoma and other cancers
- KSHV – Karposi sarcoma
- Hep B & C – Liver cancer
- Ebstein-Barr – Agreesive lymphoma
- MCPyV – Merkel cell skin cancer
- Liver fluke – liver cancer
- Schistosomiasis – bladder cancer
Emerging evidence is highlighting concerns regarding the overall mixture of commensal bacteria, which live in our gut. It is becoming clear that dominance of unhealthy strains over the healthy strains (poor gut flora) increases chronic inflammation, lowers immunity and increases cancer risk. Because the importance of gut flora, gut and general health a separate section has been dedicated to this. There are no reported links between fungus and cancer but a parasitic worm common in Egypt and Africa, causing Schistosomiasis, can irritate the bladder and lead to an increased risk of bladder cancer. Liver flukes in China, clonorchis sinensis, and Southern Asia, opisthorchis viverrini, both increase liver cancer risk.
Advice: Avoid situations or practices that increase the likelihood of catching these infections and get vaccinated where possible, particularly for hepatitis B especially if you like swimming in lakes, rivers or the sea.
Harmless low doses of low energy radiation in the form of gases, particles or waves are around us every day but there are some situations when higher concentrations can raise health concerns. The most obvious example is atomic explosions, however , individuals have also been exposed during testing of weapons or accidents in nuclear power stations. Japanese citizens who survived the initial blast and subsequent period of heightenedrisk of bone marrow failure after the Hiroshima and Nagasaki bombs in the Second World War have had a significantly increased rate of cancer. Interestingly, a study that assessed these Japanese survivors lifestyle over the period of many years showed that those who smoked or eat badly had an even greater rate of cancer but conversely those who had a high intake of polyphenol-rich foods and avoided other carcinogens successfully reduced their risk. This study eloquently highlighted that the risk of cancer following exposure to one carcinogen can be influenced by exposure to a completely different type (a synergistic effect). Today, medical X-rays, CT scans, isotope bone scans and PET scans are the most significant sources of radioactivity and although the risks are still small, it should be remembered that there should be a good reason to have an X-ray. In the household, radon gas that is naturally released from stones can accumulate in unventilated houses and concerning levels have been found in stone cottages especially in Cornwall. A recent study also recorded increased levels of radon gas in kitchens with granite work surfaces.
Advice: If you are worried about radon gas levels in your house there are various agencies which will measure them for you. Acceptable levels are less than 2pCi/L of air – if levels are above this, and certainly above 4 pCi/L – adaptions to the house, particularly improved ventilation, may be required. If you are due for a medical image which involves radiation, pause and think whether this is really necessary, will it change treatments, can it be delayed – it is well known that many are unnecessary.
There is an increased risk of cancer after therapeutic radiotherapy especially if given at a young age to men and women who were thankfully then cured. Most notable examples were radiotherapy to the abdomen in young men with a type of testicular cancer (seminoma) who then had a higher risk of bowel and bladder cancer. Women with Hodgkins Lymphoma often received (mantle) radiotherapy to their chest. As this usually included part of their breast tissue, the rate of breast caner is significantly increased, to an extent that all women in this group now should have yearly MRI screening. Chemotherapy increases the risk of leukaemia later in life and the combination of both radiotherapy and chemotherapy creates an even greater risk.
Immunosuppressant drugs are imperative after organ transplantation and are commonly used to treat a number of autoimmune diseases including psoriasis, systemic lupus erythematosis (SLE), rheumatoid arthritis, inflammatory bowel disease and polymyalgia. Immunosuppressant drugs aim to weaken the immune system to reduce the body’s reaction to what it thinks is foreign and in many cases help alleviate the symptoms and progression of these dilapidating disease. Apart from chemotherapy, commonly used immunosuppressant’s include corticosteroids (prednisolone, dexamethasone), cyclosporine and azathioprine. Some of the new targeted biological agents can also have an effect on immunity. It is not entirely clear why individuals with a lower immunity have a higher risk of cancer but hypothesis include, lower immune surveillance of early cancer cells in the blood allowing them the spread and take root when otherwise they would be killed by natural killer t-cells and an increased risk of cancer-promoting infections such as HIV, Hepatitis and HPV.
Hormonal treatments, such as tamoxifen, after many years, can increase the risk of uterine cancer, although the reduction in the rate of breast cancer relapsing usually more than outweighs this risk.
The combined pill slightly increases a woman’s risk of breast cancer. In the UK, about 1% of breast cancers in women are due to oral contraceptives. The higher risk starts to drop once a woman stops taking the pill, and disappears by 10 years. But its all one sided, the combined pill reduces a woman’s risk of ovarian and womb cancers. Hormone replacement therapy (HRT) increases breast cancer risk even when used for only a short time. Combination HRT (oestrogen and progesterone) increases breast cancer risk the most during the first 2 to 3 years and the higher doses the higher the risk. Breast cancer risk goes back down to average about 2 years after you stop taking combination HRT. Estrogen-only HRT increases the risk of breast cancer, but only when used for more than 10 years. Estrogen-only HRT also can increase the risk of ovarian cancer. There are some people who state that so-called “bioidentical” and “natural” hormones have a lower risk of breast cancer than synthetic hormones but they both increase endogenous hormone levels in the same way and have similar risks.
Advice: the risks and benefits of medical treatments should be clearly understood and appreciated before embarking on them. In most cases, the benefits out weigh the risks but there maybe ways to reduce the risks further by other healthy lifestyle choices. It would be worth researching which other factors enhance the risks such as smoking, obesity and alcohol and which may reduce them such as exercise eating a healthy diet.
The Earth’s atmosphere acts as a giant magnetic shield, blocking most of the cosmic radiation from reaching our planet. The radioactive particles or waves that make it through to the Earth’s surface have low energy and are mostly harmless otherwise, of course, we would not be here to discuss the issue. However, where the atmosphere is thin (e.g. during plane flights) the greater the cosmic radiation exposure. The obvious solution would be for planes to fly at lower altitudes although notwithstanding the noise pollution, this would be less efficient. Planes would use more fuel, have a shorter range and cost more as the thinner air allows planes to travel more easily. The “sweet spot” of flying is between 35,000 and 42,000 feet; too high and the oxygen becomes too sparse to fuel the engines, too low and the air resistance is greater. The International Agency for Research on Cancer (IARC) considers neutrons, a major contributor to cosmic radiation at flight altitudes, to be a human carcinogen. It has been suggested that female flight attendants have an increased incidence of breast cancer but they also have regular disruption of their circadian rhythm, which can also increase their risk. Nevertheless, because of their time spent in Earth’s upper atmosphere, aircrew can be exposed to several times the radiation levels of ground-based staff. The increased exposure also applied to frequent flyers depending on the ambient radiation levels at the time and duration of the flight. For example, flying round trip from New York to Tokyo seven times a year may easily put a passenger above the allowable levels of exposure that are enforced as a matter of law for medical and industrial facilities where radiation is encountered such as nuclear power stations. It is possible to estimate your exposure using this online calculator. When considering the results, bare in mind the International Commission on Radiological Protection recommends an effective dose of <20 millisieverts (mSv) per year for radiation workers, and 1 mSv for the public so if you are above this extra protective measures should be considered.
Advice: Other than flying less frequently, there are several nutritional and lifestyle measures, which have been shown to reduce markers of DNA damage and therefore may help mitigate the effects of carcinogenic ionising radiation. These will be feature in the anticancer lifestyles sections of this book but in summary they include:
- Avoid additional carcinogens when flying. If you are a smoker avoid the urge to smoke the day before or after a long flight. Avoid carcinogenic foods such as superheated sugary snacks, burnt meat products and heavily processed foods.
- Improve your exercise levels before, during and after the flight
- Boost your anti-cancer polyphenols with herbs, spices, fruit and vegetables or if a frequent flyer a polyphenol rich supplement as an extra boost before boarding
- Increase your dietary antioxidant vitamins (A, E and C) with red or orange vegetables and citrus fruits
- Ensure a healthy gut. A healthy immune system is very dependent on an optimum gut flora. Consider healthy bacteria rich food such as sauerkraut, miso soup or even multi strain probiotic supplements
Electromagnetic fields pylons, power lines and aerials.
An electric field is produced by voltage, which is the pressure used to push the electrons through wire. As the voltage increases, the electric field increases in strength. A magnetic field results from the flow of current through wires or electrical devices. Electro magnetic fields (EMFs) are produced whenever current is flowing, which usually requires a device to be turned on and include power lines and electrical wiring or electrical appliances such as shavers, hair dryers, and electric blankets. Electric fields are easily shielded or weakened by walls and other objects, whereas magnetic fields can pass through buildings, living things, and most other materials. Low frequency EMFs also include radio waves, microwaves, infrared radiation, and visible light. These EMFs are in the non-ionizing radiation part of the electromagnetic spectrum and are not known to damage DNA or cells directly (non-ionising) and are therefore not classed as carcinogens.
On the other hand, higher energy EMF can be emitted from wireless telecommunication devices and some risks of close proximity have been suggested. For example, An Italian court investigated the 60 huge steel aerials erected on farmland by the Vatican and concluded that there was a connection between the towers and cancer incidents. This included 19 child deaths from leukemia or lymphoma between 1980 and 2003. The risk appeared to be higher in children under 14 who lived less than 7.5 miles from the masts. They also found evidence of a link between the EMF and adult cancers but only among those who lived much closer to the antennae. This Italian study does not, however, match the finding from other scientists across the world. The University of California reviewed 10 of the most comprehensive studies evaluating whether electrical fields from improperly laid power lines or kitchen appliances exacerbated children’s cancer risk and found no proven links. Likewise, a study from the UK, published in the BMJ, reported that children whose mothers lived close to a mobile phone tower while pregnant did not appear to be at any higher risk of cancer than children whose mothers lived farther away. The team also gathered detailed data about all 81,781 mobile phone towers that were operational during that time. The researchers found that, in virtually every permutation of their calculations, there was no correlation between the towers and the cancer cases. The main author of the paper, John Bithell of the University of Oxford, commented that this was the largest trial in the world of its kind and people living near cell phone towers can be reassured. Other international studies analysed by the WHO have found no link between standard electricity pylons and cancer.
Advice: There does not appear to be risks from electrical appliances or living next to power lines unless they are very high energy such as those erected by the Vatican radio.
Cell phones emit heat and radiofrequency energy from their antennas and batteries. The tissues that can absorb this energy include skin, the ear, parotid salivary gland, the lining of the brain and the brain itself. Other tissues can be affected if the device is stored next to skin such as in the bra or trouser pocket. Ninety three percent of the UK population now have a mobile phone, a figure that has increased three fold since since 2003. Over this time, the number of cell phone calls per day, the length of each call, and the amount of time people use cell phones have also intensified. If the energy they produce influences the risk of cancer, even by a small amount, it would affect a vast sum of people and hence the reason why several public health organisation have conducted numerous studies to see if the incidence of disease has increased in the tissues nearest to the antenna.
Reassuringly the radiofrequency energy produced by cellphones is non-ionizing radiation. In animal studies, conducted by the National Institute of Environmental Health Sciences (NIEHS), cellphones have not been found to cause cancer or to enhance the cancer-causing chemicals. The only consistently recognized biological effect of radiofrequency energy is heating. The ability of microwave ovens to heat food is one example of this effect of radiofrequency energy. It has been suggested that radiofrequency energy might have other mechanisms of harm such as affecting glucose metabolism but the evidence for this is weak and conflicting. Another study investigated whether cell phones affects the flow of blood in the brain and found no evidence of such an effect.
In terms of an increased risk in humans, the massive Surveillance, Epidemiology, and End Results (SEER) programme found no increase in the incidence of brain or other central nervous system cancers between 1992 and 2006, despite the dramatic increase in cell phone use in this country during that time. One French case-control study (CERENAT) found no association for either gliomas or meningiomas when comparing regular cell phone users with non-users. However, the heaviest users did have significantly increased risks of both gliomas and meningiomas. This was finding was not substantiated in 3 other large epidemiologic studies (Interphone, Danish, Million Women Studies), which between them analysed thousands of cellphone users over many years.
Other studies specifically assessed risks in children who have theoretically higher risks for three reasons. Their nervous systems are still developing and, therefore, more vulnerable to factors that may cause cancer. Their heads are smaller than those of adults and consequently have a greater proportional exposure to the field of radiofrequency radiation that is emitted by cell phones. And, children have the potential of accumulating more years of cell phone exposure than adults do. Thus far, the data from studies in children with cancer do not support this theory. A large case-control study called CEFALO, conducted in Denmark, Sweden, Norway, and Switzerland looked at children who were diagnosed with brain tumors between 2004 and 2008. Researchers did not find any association between cell phone use and brain tumor risk either by time since initiation of use, amount of use, or by the location of the tumor.
There have been some published case reports and subsequent media coverage of issues related to how phones are carried on the body. Most notably, a 51-year old woman from Bracknell in the UK had the habit of storing her cellphone in her bra. After 15 years she developed breast cancer on the same side, directly under its usual position. Another 50 year old woman from Pontypool, Wales, was found to have breast cancer also in the precise place where she normally stored her mobile phone. In Stuttgart, Germany, a 21-year-old women, with no family history of breast cancer or BRCA mutations developed breast cancer on the same side she regularly stored her phone since an early teenager. These anecdotal reports are by no means proof but do a raise some concerns as this intense local exposure over such long periods of time who be hard to replicate in animal experiments.
What do expert organisations conclude about the cancer risk from cell phone use?
Despite the lack of evidence of direct harm, in 2011, the International Agency for Research on (IARC), classified cell phone use as “possibly carcinogenic to humans,” based on limited evidence from human studies, limited evidence from in rodents, and inconsistent evidence from mechanistic studies. The America Cancer Society (ACS) commented that there could be some cancer risk associated with radiofrequency energy, but the evidence is not strong enough to be considered causal and needs to be investigated further but in the mean time individuals could limit their radiofrequency energy exposure with the guidelines listed below. The National Institute of Environmental Health Science (NIEHS) states that the weight of the current scientific evidence has not conclusively linked cell phone use with any adverse health problems, but more research is needed. The USA Food and Drug Administration (FDA) notes that isolated studies reporting biological changes associated with radiofrequency energy have failed to be replicated in human epidemiologic studies. In 2015 the European Commission Scientific Committee concluded that the available data do not show an increased risk of brain tumors or other cancers of the head and neck region for either adults or children.
Advice to reduce exposure to radiofrequency energy from cellphones?
Mobile phones are more likely to cause harm by distracting drivers or even waling into other pedestrians or lamppost. The likelihood of them causing cancer is small but until further definitive trials are conducted these common sense measure seem sensible:
- Reserve the use of cell phones for shorter conversations
- Use a landline phone for longer call and when available.
- Switch sides of the head from time to time
- In young men, do not regularly store your phone in your front pocket – next to your testes
- Do not store your phone in your breast pocket or bra
- Use a device with hands-free technology, such as wired headsets, which
- Generally place more distance between the phone and the head of the user.
Industrial and occupational chemicals
Doctors in the early Victorian era were the first to observe the link between occupational chemical exposure and cancer. They observed that chronic soot contact with the scrotal skin in the underpants of chimney sweeps, caused squamous cell cancers. Since then, there have been thousands of worker exposed to toxic chemical causing great distress to them and enormous cost to industry. Asbestos, used to be, used as a fire resistant insulation and causes mesolethioma, an aggressive cancer affecting the lining of the lung. Electricians, boilermakers, builders and their wife’s who washed their clothes were commonly exposed but inhalation of asbestos fibres could also arise from a number of unexpected sources. A famous example is the actor Steve McQueen who died of mesothelioma 15 years after he started wearing asbestos masks, first worn during the filming of “The Hunter”. Bladder cancer and lymphomas are more common among workers in the alanine dye and rubber industries. Chronic wood and leather dust exposure increases the risk of cancer behind the nose. Workers mining or manufacturing goods using chromium, magenta, cadmium, arsenic, haematite, aluminium, iron and steel are at higher risks as well as those involved in coal gasification and processing. In the 1920’s a scandal emerged after hundreds of women in three United States radium factories developed devastating cancers of the jaw. To order to accurately apply the luminous mixture of carnotite-extracted radium, onto the watch dial, women had the habit of sucking the brush tip contaminating their mouth. There are numerous other examples of industrial exposure which are outside the scope of this book but reading particularly interested in this topic can find more information on the FDA website.
Advice to reduce work place chemical exposure. Most work places are well equipped with masks and protective clothing so it’s advisable to use them regularly. People working in less regulated smaller businesses should avoid the temptation to cut corners. Most at risk, are people who work in their unventilated garages and sheds with chemicals – it’s not macho to avoid protection if you see a friend or relative exposing themselves to these risks – speak up!
The term circadian is derived from the Latin phrase circa diem, which means about a day. A part of the brain called the anterior hypothalamus serves as a circadian master that controls rhythmicity that is important for every cell in the body via the activity of wide range of clock-controlled genes that regulate biochemical, physiological processes, and proliferation. More precisely, the circadian cycle alters how our genes are presented (expressed) to the RNA, which subsequently makes the proteins and enzymes that regulate biochemical and growth pathways. This is called epigenetics and it does this by altering a chemical reaction called methylation, which in turn influences how tightly wound or loose our DNA is coiled. If tight, it is harder for RNA to bind, which then slows biochemical processes. If loose the biochemistry, growth and cell division increase. Put practically, a healthy circadian rhythm enables cell cycles slow at night (helping them repair). It also helps us get to sleep, slow metabolism at night and, reduce the motility and secretions of the gut and production of urine by the kidneys.
Numerous laboratory experiences have shown that chronic interference with this normal rhythm is implicated in several pathologic conditions, including tumorigenesis and progression of cancer. In humans epidemiology studies have linked occupations that regularly cause circadian disruption (desynchrony) to an increased susceptibility to a wide range of cancers included breast, ovarian, lung, pancreatic, prostate, colorectal and endometrial cancers, non-Hodgkin’s lymphoma (NHL), osteosarcoma, acute myeloid leukemia. In these studies the risks of cancer were greater with the number of years, the frequency of rotating work schedules, and the number of hours per week working at night among human night-shift workers. Due to the prevalence of night shift-work schedules in modern societies, the World Health Organization’s International Agency for Research on Cancer (IARC) listed “shiftwork that involves circadian disruption” as a probable carcinogen in 2007.
Interestingly, some cancers cells have developed mutations which help them to ignore circadian regulatory pathways, allowing them to grow “flat-out” 24/7. Scientist are currently investigating drugs which target dysregulation genes (known as Per1, 2, 3 and Bmal1), restoring circadian rhythm hence slowing the cancer cell cycle, which not only slows growth rates but enables abnormal cells to self disrupt as it gives the apoptosis mechanisms a chance to work. A process with should shrink cancers without affecting normal cells.
Levels of cortisol, melatonin and many other hormones cycle throughout the day. Cortisol peaking shortly after waking and melatonin peaking during the middle of the night. Between them they tell all the cells in your body what time it is. The circadian clock is set by a variety of external factors, but most importantly light during the day and dark at night. Not only are the levels of hormones different, the sensitivity of different types of cells to different hormones can also cycle. This impacts every system in your body, from your immune system, to how well you digest your food, to how much insulin is released in response to sugar intake, all change based on the time of day. It is not a surprise then that when your circadian rhythms are properly regulated, you sleep well, you have energy in the mornings, you are in a better mood, have a lower risk of depression and it reduces your risk of chronic diseases including cancer. As we get older, melatonin decreases and researchers are investigating has also been investigated extra supplementation for its anti-aging potential.
Advice how to restore and maintain a healthy circadian rhythm: It is important maintain a regular light-dark cycle as this affects the production of melatonin, cortisol and other regulatory hormones. This is difficult if you are traveling across time zones and working at night but the following tips may help:
Try to get bright (blue) light exposure during the day: One of the best ways to set your circadian clock is to be exposed to bright light (ideally sunlight) during the day. The component of sunlight that tells your circadian clock that it’s daytime is blue light which trigger sensitive photoreceptors in the eyes and to a lesser extent skin. This is one explanation why you feel in a good mood looking at a blue sea. In generally try to get as much natural light as possible in the day but as a minimum if it’s a sunny day, as little as 15 minutes may do the trick or if cloudy, 30 minutes to an hour. If there is no opportunity to get natural light in the day, a biological alternative would be to put your head into a light box for at least 15 minutes at roughly the same time every morning or mid-day. Another option is to make many small changes to brighten your environment during the day by using sunlight spectrum light bulbs in your house (but you’ll want to avoid using these light bulbs in the evening), keep curtains open during the day and try to face a window
Avoid bright and blue light in the evening or at night: Just as it’s important for your body to get the signal that it’s daytime during the day it’s important to tell your body it’s nighttime once the sun goes down. This means avoiding blue light and sticking with red and yellow wavelengths of light as well as keeping the overall light level much dimmer. You can send this important “darkness signal” to your circadian clock by keeping your indoor lighting as dim as possible in the evenings with dimmer switches, or just turning on fewer lights, in conjunction with investing in red or yellow light bulbs for whatever lamps will be used in the evening. If you plan to use a computer monitor or watch TV, there are two options. The first is to install a flux application on your computer phones or tablets and set the screen brightness to the lowest setting. The second, and probably the best biohack is to wear amber tinted glasses for the last 2-3 hours of your day. In fact, several scientific studies show that wearing amber-tinted glasses in the evening improves sleep quality and supports melatonin production. A more sophisticated option for getting both your bright blue light in the day and your dim red light in the evening is to use programmable light bulbs where you can set the color spectrum and the brightness for the time of day. Once you get to bed, sleep in a completely dark room, cover up any LED lights on phones, toothbrushes, baby monitors, or whatever other gadgets you have plugged in in your room and ditch the nightlights or switch to ones with red light bulbs. Blackout curtains help as can white noise generators especially if there are high frequency/pitch noises in or outside of your home since these are very stimulating for the brain. If you need to use the loo at night either learn to navigate in the dark or use as little light as possible.
Reduce and manage stress: You probably recognize cortisol as being the master stress hormone but as mentioned above it’s also a very important circadian rhythm hormone. This means that if you’re under stress, not only do you have all the effects of elevated and dysregulated cortisol to deal with, but you also disrupt your circadian rhythms. The section relating to psychological morbidity later on in the book will cover this in more detail. But salient tips would be making changes to the structure of your work social life, asking for help or making time for regular exercise life, taking up meditation, yoga, going for a walk at lunch, taking a bath, or just making time for a good laugh or a hobby in your life.
Aim for regular bed times and try to get enough sleep: Your melatonin starts increasing about two hours before bed to prepare your body for sleep. If you’re muscling through that with a sugary snack, a scary movie, or whatever else you do to keep yourself awake at night, you are affecting your circadian rhythms. Aim for 7-10 hours of sleep every night and most people will need between 8 – 9 hours). This means shifting your bedtime earlier so you aren’t struggling through that fatigue to get a second wind (which by the way, usually also means you’re increasing your cortisol right when it’s supposed to be at its lowest).
Stay cool at night: The temperature that you’re sleeping in is also a cue to your circadian clock. Ideally your indoor temperature at night should be lower than temperatures in the day
Ditch the alarm clock: Waking up to a jarring noise is very stressful. If you don’t have the luxury of sleeping until your body naturally wants to wake every morning (which is the best option for protecting your circadian rhythms and overall health), use a light alarm which gradually gets louder can be set on most mobile devices
Physical activity: Getting some kind of activity during the day has been shown in clinical trials to support melatonin production. There are a few exceptions though. For example, intense activity in the evening can delay your melatonin production (basically keep you revved up longer in the evening) unless it’s routine (say, you always go to fitness class in the evening and your body has adjusted). Working out in a really bright environment in the evening can be a problem (the combination of bright lights, as may be in your gym, and activity in the evening suppresses melatonin). But, other than that, any kind of activity any time of day (even better if it’s outside!) will help support circadian rhythms
Manage your blood sugars: Many hormones are sensitive to swings in blood sugar, including both melatonin and cortisol. Eating a big meal just before bedtime will increasethe risk of heart burn and indigestion, Avoid spikes in blood sugar from high glycemic load foods, instead concentrate on complex carbohydrates and even healthy fats as these will help you avoid hunger pangs overnight.
Eat melatonin-rich foods: Melatonin is made from serotonin, which in turn is made from tryptophan. Seafood has more tryptophan while also having less of the other amino acids, which compete with tryptophan to cross the blood-brain barrier. Montmorency and morello cherries are also rich in plant precursors of melatonin (known as phytomelatonins). So, eating more seafood and cherries is a good way to boost production both of serotonin and melatonin. Seafood also contributes long-chain omega-3 fats to your diet that also help support circadian rhythms by improving general brain health. Ginger also has phytomelatonin so a good nightcap would be some grated ginger with hot water, a little lemon and mint but avoid drinking a lot of liquids prior to bed as it fills the stomach and makes you need the bathroom at night.
Alcohol, caffeine and cigarettes: Discontinue or reduce the use of caffeine (tea, coffee, energy drinks) after 4pm. Alcohol may make you initially sleepy but often you then have a restless night waking. Nicotine is a stimulant which can keep you awake so avoid smoking at night. Heavy smokers suffer withdrawal of nicotine at night so they wake up anxious and alert
Dietary melatonin supplements Melatonin (N-acetyl-5-methoxytryptamine) is licensed in the UK for adults who are aged 55 or over but it is not recommended to take more than a 13 week course. It can be obtained with a prescription and comes in the form of a ‘prolonged-release’ tablet. In the USA and many countries it is freely available over the counter. Double-blind randomised studies have shown that this hormone helps people sleep, shortens the number of awakenings in the night, and improves the quality of sleep but it is not a long term solution. It is most useful in treating jet lag, as it promotes quicker recovery from that muzzy stage one may experience after extended periods of flight.
Periodontitis otherwise known as gingivitis or gum disease is caused by chronic oral infection by gram-negative anaerobic bacteria allowed to multiply by poor dental hygiene. Several large robust studies have reported that individuals with gum disease have a higher risk of cancer. In one notable publication, 7466 people had their level of gum disease recorded regularly. Over the next 15 years, of the 1648 who subsequently developed cancers and 547 who died of cancer, nearly twice as many occurred in people who had marked gum disease. Another study from Helsinki University used data from 70,000 adults and discovered a clear link between periodontitis and mainly colon cancer but also cancer of the pancreas.
The precise mechanism that gum disease can cause cancer is not completely understood but there are a number of hypotheses. First, people with gum disease are more likely to have other bad habits such as higher sugar intake, obesity and smoking but clever statisticians in these two trials, highlighted above, factored out these two confounding risk factors proving gum disease is indeed and independent risk factor. Second, periodontal pockets may act as reservoirs for cancer promoting bacteria and viruses such as human papilloma virus, cytomegalovirus and Epstein Barr. Third, microorganisms such as s.typhi and pasteurella multocida and their bacterial endotoxins can facilitate tumour development by interfering with the cellular signaling molecules as well as inducing mutations in the tumor-suppressor genes and proto-oncogenes. One study also found that DNA from another bacteria commonly found in disease gums, called treponema denticola, was found embedded in cancers lower down the GI track suggesting that the bacterial DNA could have directly helped trigger gut mucosa to become cancerous. Forth, periodontitis creates a state of chronic inflammation which results in constant release of c-reactive protein, inflammatory cytokines, chemokines, growth factors, activation of COX2 and prostaglandins all of which are associated with cancer development and progression by increased proliferation, migration, angiogenesis and inhibition of apoptosis.
Advice to avoid gum disease: Visiting the dentist regularly is wise but the day-to day-measures to prevent the formation of dental plaque and painful caries are most important:
- Eat less sugar and fewer sugary foods
- Avoid sucking sugary sweets – opted for sugar free chewing gum
- Clear the gaps between the teeth of meat or debri after a meal with a tooth pick
- Cleaning teeth at least twice a day
- Take care of your toothbrush – alternate, clean after use, replace if frayed or damaged
- Swish your mouth with water after every meal to displace food from between the teeth.
- Clean the tongue as well as the teeth
- Floss every day or use a water jet.
- Avoid alcohol-containing mouth washes as these could upset the healthy bacteria
- Consider a probiotics mouth wash – crack open a probiotic capsule is water and swish
Cosmetics and antiperspirants:
In 2004, Professor Philipa Darber, from Reading University, wrote a report proposing that cosmetics were a contributory factor in the rising incidence of breast cancer and created a media storm. This hypothesis was on the basis that there is a disproportionality higher incidence of breast cancer in the upper outer quadrant of the breast, where more than half of breast cancers originate, and where chemicals are applied to the underarm and left on the skin allowing for low levels to be absorbed over several hours. In particular, aluminium salts which are responsible for the anti-sweating affect of antiperspirants and parabens, which are included as preservatives. This observation was supported by another study in 2007, from Keel University, which actually measured the presence of these chemicals in post mastectomy breast tissue.
Both aluminium (a metaloestrogen) and parabens (xenoestrogens) have been shown to increase chronic inflammation, alter gene expression, stimulate angiogenesis and cancer invasion in lab rats. More relevant to breast cancer, they have been shown, to mimic the animal oestriol or estrone stimulating normal breast cells to grow faster leading to disorganised hyperplasia and with the increased cell division rate comes an increased risk of mutations, atypia and eventually cancer. This is important because of all the risks factors for breast cancer, one of the most important is lifetime exposure to oestrogen. The potential contribution of these topical oestrogenic chemicals, even in very small doses environmental doses therefore needs to be taken more seriously especially if they are combined with other oestrogenic environmental chemicals and used over many decades. Other chemicals commonly found in cosmetics, topical creams, gels and shampoos which may have weak oestrogenic and negative effects include phthalate esters in moisturisers and plasticisers, polycyclic musks, nitromusks and benzyl benzoate in fragrances, triclosan as additional preservative; UV light filters benzophenones, octyl-methoxycinnamate camphor and octamethylcyclotetrasilazane as conditioning agents.
In humans, researchers from Denmark, traced absorption of radiolabelled aluminum into blood following topical application to the underarm of aluminium based antiperspirant salts. Another study, showed that topical application of creams containing the chemical agents, resulted in measurable increases in these chemicals in the blood and urine within hours. In particular, urine levels of phthalates, parabens, benzophenone-3 and triclosan decreased when individuals who stopped using products containing these chemical components, which clearly shows that these burdens can be reduced by individual choice.
It is generally accepted that these oestrogenic contaminants enter the body in small amounts but the evidence they could have unwelcomed physiological effects on the body or do harm is scant and further trials are most certainly needed. A case published in the New England Journal of Medicine, in 1988, describes the development of gynecomastia (enlargement of breasts) and hypogonadism (low male hormone) in a man with long-term exposure of his hands to xenoesotrogenic-rich embalming creams. His breasts disappeared, and his loss of libido and fatigue improved after he started wearing gloves at work. A month girl in Italy had premature breast development together with menstruation and uterus enlargement, caused by exposure to components in her mother’s hair lotion. In another case, a patient presented with bone pain and extreme fatigue after continuous use of an aluminium based antiperspirant for many years. After stopping, her plasma aluminum levels fell from to within the normal range and the associated symptoms disappeared.
Only a few studies have investigated a possible relationship between breast cancer and underarm antiperspirants/deodorants. They have been small, retrospective or cohort studies and the conflicting results make it difficult to reach a definite conclusion. For example, a study, published in 2002, interviewed 813 women with breast cancer and 793 women with no history of breast cancer. It did not show any increase in risk for breast cancer among women who reported using an underarm antiperspirant or deodorant or those who applied these products within 1 hour of shaving with a blade razor (which may have increased absorption by breaching the skin). Likewise, a small study, published in 2006, also found no association between antiperspirant use and breast cancer risk, comparing 54 women with breast cancer and 50 women without breast cancer. On the other hand, in 2003, a retrospective study found that the frequency of underarm shaving and antiperspirant or deodorant use among 437 breast cancer survivors was higher and women who did this, started at an earlier age.
Lotions, perfumes, hair sprays, nail polish remover and air fresheners can also contribute to the level of volatile organic compounds (VOC) in the atmosphere. Studies have not yet linked these tiny particles with cancer but there are risks of asthma, heart disease and stroke. A study published in 2018 from the Centre for Ecology and Hydrology in the UK suggested these personal care products in combination with paint, disinfectants and furniture polish contributing almost as much as car pollution in urban areas.
In conclusion, aluminium, parabens and other cosmetic chemicals, despite suggestions of potential harm in laboratory experiments, have not been proven to increase cancer rates in humans, either in cohort or in direct clinic studies, although these would be very difficult, if not impossible to design a large enough randomised trial. Nevertheless, breast cancer specialists have concerns with oestrogenic chemicals within cosmetics that can be absorbed into the breast and blood stream. Most notably, the prestigious San Antonio Breast Cancer Symposium highlighted studies which have shown that widely available moisturisers and cosmetics contain significant levels of xenoestrogenic chemicals and despite the lack of direct evidence, they concluded that women with breast cancer should forgo using topical moisturizers, shampoos and shower gels that contain parabens or other oestrogenic preservatives, as there is a chance that they may interfere with their treatment and increase the long term risk of relapse. These concerns have encouraged some manufacturers to remove parabens from their products, but in many items such as shower gels and shampoo they can still be seen on the label, so it is worth checking before you buy.
Advice to avoid chemicals in cosmetics: Sweat is odourless. It is only when it mixes with bacteria and protein that it becomes smelly. The obvious defence against body odour is to wear a clean shirt or blouse every day and wash thoroughly particularly the vulnerable areas such as the feet, groins and armpits. It’s a good idea to give your sweat gland a chance to “have a good sweat” during exercise or sauna to wash out bacteria and protein from the glands and seat ducts so do not apply antiperspirants before hand. Then after a thorough wash, it means that your sweat is much less likely to smell. Avoid sweating during the day by removing clothes when you feel warm, take your coat off a soon as you enter a hot room. Although, often tricky avoid stressful situations as this will make you sweat more. Antiperspirants, which prevent sweating or deodorants which have antibacterial actions or masking fragrances certainly have their place, but bare in mind these chemicals are applied to the body throughout an entire lifetime usually in combination with numerous other potential carcinogens so it would be sensible to make some efforts to avoid excessive use. Natural, plant based alternatives are now becoming available on the market which harness the fragrances and anti-microbial proprieties of essential oils. They are not liked by everyone but they are definitely worth a try as unlike synthetic brans the oils have the additional advantages of containing bioactive phytochemical which have anti-inflammatory and anti-oxidant properties. The following tips will help reduce the total oestrogenic load from cosmetics:
- Use plain soap instead of shower gels which contain parabens and preserving chemicals
- Limit their use to days which mater – giving talks, dates, long days travelling.
- Take chemical-free water wipes to work to clean armpits during the day
- Avoid applying underarm cosmetics, within 1 hour of shaving to reduce blood absorption
- Consider natural alternatives which contain antibacterial essential oils
Hair dye use is ubiquitous and perhaps even more commonplace than many people will admit. Colouring the hair can help maintain body image and self esteem for hundred of thousands of people, particularly in Europe and the USA where it is estimated that more than one-third of women over age 18 and about 10% of men over age 40 use some type of hair dye. Modern hair dyes are classified as permanent or oxidative, semi-permanent or temporary. Permanent hair dyes, which make up about 80% of currently marketed products, consist of colorless dye “intermediates” and dye “couplers.” In the presence of hydrogen peroxide the intermediates and couplers react with one another to form pigment molecules. Semi-permanent and temporary hair dyes are non-oxidative and include colored compounds that stain hair directly. Over 5,000 different chemicals have been used in hair dye products, some of which are reported to be carcinogenic in animals albeit at much higher quantities than are used in humans. Before 1970, carcinogenic chemicals including aromatic amines, were more commonplace but many of these chemicals have since been removed.
Early epidemiologic studies have reported an increased risk of bladder cancer amoungst hairdressers and barbers. Although some small studies have linked the personal use of hair dyes with increased risks of certain cancers of leukaemia, breast and bladder cancer, other studies have not shown such links. A Danish research team pooled data from 4,461 people for 4 of the biggest trials and concluded that women who began using hair dye before 1980 had a slightly increased risk (of NHL compared with women who had never used hair dye, whereas no such increase in risk was seen for women who began using hair dye after 1980. Based on this review of the evidence, the International Agency for Research on Cancer (IARC) concluded that some of the chemicals workers are exposed to occupationally are “probably carcinogenic to humans” but due to the lack of recent data concluded that personal use of hair dyes is “not classifiable as to its carcinogenicity to humans”.
Advice: The chance that personal use of hair dyes are carcinogenic is very small. Nevertheless, ongoing research is always necessary, as formulations change and as they are used by so many, over so many years. In the mean time, it would be sensible to wear gloves, apply the dye in a well ventilated room, rinse hair and skin off thoroughly after use and ensure a healthy intake of polyphenols on the day of use to act as an antidote.
Talcum powder is made from talc, a mineral made up mainly of the elements magnesium, silicon, and oxygen. It absorbs moisture well and helps cut down on friction, making it useful for keeping skin dry and helping to prevent rashes. In its natural form, talc contains some asbestos, but since the 1970 cosmetic products have been asbestos free. Obviously before 1970 talc products were likely to be carcinogenic but the evidence about asbestos-free talc and cancer, is less clear.
Studies that exposed laboratory rats, mice, and hamsters to asbestos-free talc in various ways have had mixed results, with some showing tumor formation and others not finding any. In humans, some studies of talc miners and millers have reported an increase risk of lung cancer, but this may well have been caused by the asbestos and radon gas in the mines. There have been no increased risk of lung cancer reported with the use of cosmetic talcum powder. It has been suggested that talcum powder might cause cancer of the ovaries if the powder particles applied to the genital area or on sanitary napkins, diaphragms, or condoms were to travel through the vagina, uterus, and fallopian tubes to the ovary. Clinical findings, from epidemiological and cohort studies, have been mixed, with some studies reporting a slightly increased risk and some reporting no increase. But these types of studies can be biased because they often rely on a person’s memory of talc use many years earlier. Considering all the evidence, the IARC classifies talc that contains asbestos as “carcinogenic to humans.” They classify inhaled talc, not containing asbestos, as “not classifiable as to carcinogenicity in humans.” and based on limited evidence from human studies of a link to ovarian cancer, the genital use of talc-based body powder as “possibly carcinogenic to humans.”
Advice: For any individual woman, if there is an increased risk with modern cosmetic talc, it is likely to very be small. Nevertheless, it is sensible to use talc sparingly, avoid inhalation and avoid applying directly to the genitals, particularly the vagina.
Burning everyday paraffin-wax candles can emit a multitude of toxic chemicals, including toluene and benzene. While it is nowhere near as harmful to light an occasional candle as it would be, for example, to smoke a pack of cigarettes a day, researchers at South Carolina State University suggest that frequent candle burning in tight, unventilated areas has been implicated in lung cancer, asthma, and skin rash. Researchers explained that the candles, which are made from petroleum, are a source of known human carcinogens and indoor pollution. Scented candles also increase atmospheric volatile organic compound levels contributing to general smog levels.
Advice: It is best to avoid their use, the create smoke and are a fire risk. If you feel they are the only way to create a romantic atmosphere, candles made from beeswax or soy wax, although more expensive, are apparently safer, because they do not release potentially harmful hydrocarbon pollutants.
A study published in the Journal Cancer in 2011 showed that married cancer patients lived longer than single ones. Data indicated that 65% of married patients survived at least five years after diagnosis, compared with 57% of those who had never been married, 52% of the divorced patients and 47% of widowed. The researcher did not claim that being single was carcinogen but postulated that married patients have a built-in support system and are more likely to stick to their treatment regimens. It is also likely that they may even be in better health to begin with.
Advice: Although easier said than done, and rather obvious, try to marry someone you get on with preferably love, who is able to help you stay fit and support you physically and mentally after an illness.
Having a desk job:
An analysis of 45,000 men aged 45 to 79 published in the British Journal of Cancer found that those who had highly physical jobs were 28% less likely to develop prostate cancer than those who spent most of their working lives sitting. The researchers, from the Karolinska Institute in Sweden, concluded, that not sitting for most of the time during work or occupational activity and more active living is associated with reduced prostate cancer incidence. Other studies have shown that ..
Advice: If you have a desk job try to walk before and after work and in your lunch break. Simple measures such as park your care further away, getting off the tube or bus a stop earlier can help the days exercise levels. During work time, try to stand up and stretch at regular intervals, use the bathroom or tea room a level up to add some stairs to your activities. Some work places have adjustable, or even standing, desks.
Watching TV A study published recently described a link between the time an individual spends watching television and his or her risk of death.. They tracked the TV-viewing habits of 8,800 adults and followed them for six years. Every hour of daily TV watching increased the risk of dying from any cause by 11% percent, for cardiovascular diseases the increased risk was 18 percent, and for cancer it was 9 percent. The research point out that this effect probably correlated with lack of exercise rather than a direct negative effect of the TV’s rays – although more research is needed
Advice: Avoid long periods of sedentary behavior, which includes watching TV. Do not tempted to watch a box set in one go. Get up between programs, even walking up and down stairs will help if you are not able to walk around the block
High temperature of foods (hot liquids)
It seems like every couple of months there’s a new link to the dreaded c-word, so what could it possibly be now? According to the World Health Organisation’s cancer agency, it’s any liquid that could be described as “very hot”. While the International Agency for Research on Cancer (IARC) was unable to find conclusive evidence to suggest coffee itself causes cancer, a review released of 1000 humans and animals found that any liquid consumed when hotter than 65 degrees celsius is probably doing carcinogenic damage to your oesophagus.
Advice: allow drinks to cool before swallowing. Chew food well to ensure not hot chunks escape attention as are swallowed.
Plastics and other xenoestrogenic chemicals
Some chemicals can increase the risk of cancer by having a chemical structure similar to oestrogen, which stimulates hormone sensitive tissues to grow rapidly and often in an uncontrolled way. These carcinogens are often called endocrine disrupting chemicals (EDC’s) or xenoestrogens and are usually man-made environmental pollutants although some pesticides and herbicides can have some EDC properties. The most common group of EDC chemicals are the polychlorinated biphenyls (PCB) and organochlorines found in car pollution, fuels, polycarbonate plastic bottles drugs and food containers. Other xenoestrogenic chemicals include dioxins, which are released in some industrial processes, and Bisphenol A (BPA), which is a plasticizer used for manufacturing polycarbonate plastics and epoxy resins. It is difficult to avoid these chemicals in a modern environment, as they ubiquitous, it’s a sad fact, that the amount of plastics found in the sea, rivers and lakes is increasing exponentially.
Researchers from academic centres have demonstrated that if the same oestrogenic pollutants in our environment are given to laboratory mice, they induce and promote mammary cancers. A further study in 1993 showed that rhesus monkeys developed endometriosis and a thickened uterus, the first stage in developing cancer after being fed food that contained dioxin, over a four-year period. Both endocrinologists and reproductive biologists have suggested that long-term exposure to xenoestrogens might underlie the rise in endometriosis, fibroids and infertility. In men, many scientists believe that oestrogenic pollutants are responsible for some disturbing trends such as decreasing sperm quality and lower testosterone production. In the animal kingdom, plastic infiltrating the water supply may explain the shrinking sizes of alligator penises! If this rate of oestrogenic pollution continues it poses a major risk to mankind. Although it sounds like a script from a Woody Alan film, men’s libido will continue to drop and even if they manage to muster up enough motivation to have sex, with their ever shrinking penises, their stunted sperm counts would be unlikely to fertilise women.
In terms of cancer, a report published in the International Journal of Andrology has linked pollutant oestrogenic chemicals in mothers’ breast milk with an increased rate of testicular cancer in their male children. More specifically, researchers found that Danish men were up to four times more likely to have testicular cancer, genital abnormalities and a lower semen quality than men in neighbouring Finland. Investigators measured higher levels of dioxins, polychlorinated biphenyls (PCBs) and xenoestrogenic pesticides chemicals in samples of breast milk from women in Denmark than in Finland. Why women in Denmark should have more of the chemicals in their breast milk than their Finnish neighbours remains unclear. In addition to hormone related conditions and cancers, such as testicular and breast cancer, animal studies have shown that polychlorinated biphenyls increase the risk of liver cancer and lymphoma by up to 65 percent compared to animals fed a chemical free diet.
Plastic pollution can also have other potentially harmful non-hormonal influences on cancer processes. For example, bisphenol A (BPA) can cause epigenetic disruption of DNA (via methylation, histone acetylation and disturbance of miRNA binding) leading to over expression of genes which promote cancer. Polybrominated diphenyl ethers (PBDEs) have been shown to cause excessive production of inflammatory cytokines (increased IL-1β and tumor necrosis factor) which interferes with the normal expected anti-inflammatory response to pathogens (decreased IL-10). Chronic inflammation over time is linked to greater cancer risk as well as a host of other disorders such as arthritis, diabetes and heart disease.
Advice to reduce exposure to plastic and xenoestrogenic pollutants: Firstly, don’t get paranoid these are everywhere the best you can do is to reduce and minimize your exposure and concentrate on other anti-cancer lifestyle strategies to reduce your risk. Here are some tips to help you reduce your exposure:
- Try to choose non-plastic packaging or bottles such as glass, stainless steel, lead-free ceramic and even coated aluminum.
- Choosing whole, fresh foods where possible will also reduce your exposure to synthetic additives and preservatives found in processed foods.
- Store food in china or glass containers
- Keep plastic water bottles away from heat or the sun’s ultraviolet rays as this causes leaching of the chemicals into the foods
- Try to buy from local farmers and what’s in season – this reduces transport pollution and need for packaging
- Look for products packaged in plant-based plastics like PLA.
- Air pollution is all around us but try to avoid exercising besides busy road – A recent study eloquently showed that blood levels of benzene, sulfar dioxide and hydrocarbons were ten times lower in a group who jogged in Hide Park rather than along the busy Oxford Street