Healthy and unhealthy fats explained
Fats are needed for brain development, enzyme production and are essential for a number of important cellular functions. They are an excellent source of slow release energy as they have a low glycaemic index avoiding peaks and troughs in blood sugar. However, too much intake, especially of the wrong type of fats, can lead to over storage resulting in obesity, fatty liver and hardened arteries leading to heart disease, cancer and a host of deliberating chronic diseases. This page explains which fats we should eat more of, which to avoid and which other lifestyle factors help healthy cholesterol levels and balance of essential bioactive omega fatty acids.
Types of edible fats: Cholesterol is the main component of animal cell walls; trans-fats are mostly harmful man main forms; other edible fats are made up of a two components, glyceroles and fatty acids. Plant sterols are similar to cholesterol but general lower serum cholesterol levels. If fats they contain three fatty acids they are known as triglycerides and are the main fats in the human body. They are defined as saturated or not depending on the number of carbon to carbon (c=c) double bonds they contain and can occur in both plants and animal fats.
Categorisation of fats in our food chain
Saturated triglycerides (no C=C double bonds)
- Mainly plant based
– lauric acid
– myristic acid
- Mainly animal based
– palmitic acid
– stearic acid
– butyric acid
Unsaturated triglycerides (contains C=C double bonds)
- Monounsaturated; 1 double bond linked with omega 7 & 9 fatty acids
– Omega 7
– palmitoleic acid
– vaccenic acids
– Omega 9
– oleic acid
– erucic acid
- Polyunsaturated; >1 double bond linked with omega 3&6 fatty acids
– Short chain omega 3
– alpha-linolenic acid (ALA)
– eicosatetraenoic acid (ETA)
– Long chain omega 3
– eicosapentaenoic acid (EPA)
– docosahexaenoic acid (DHA)
– Short chain omega 6
– linoleic acid
– Long chain omega 6
– gamma-linolenic acid (GLA)
– di homo gamma linoleic acid (DGLA)
– arachidonic acid (AA).
– Low Density Lipoproteins (LDL)
– High Density Lipoproteins (HDL)
- Plant phytosterols
– Sterols (unsaturated with c=c bonds) – sitosterol and campesterol
– Stanols (saturated with no c=c bonds) – sitostanol and campestanol
Triglycerides and fatty acids
These can be saturated or unsaturated but to be called triglycerides they should contain three fatty acids to one glycerol. They are not absorbed into the body as a whole chemical, instead, in the gut, the enzyme lipase (from the pancreas) and bile (from the liver) splits the fatty acids from the glycerol section (lipolysis) and the elements are absorbed separately. The triglycerides are then rebuilt in gut wall and packaged together with cholesterol and lipoproteins to form chylomicrons or very low-density lipoproteins (VLDL) for transport around the body. Tissues can capture the chylomicrons, releasing the triglycerides to be used as a source of energy.
Liver cells can also make and store triglycerides when we don’t need them for energy. When the body then requires fatty acids as an energy source, the hormone glucagon signals the breakdown of the triglycerides to release free fatty acids. These fats are the first to be used up when we expend energy so drop in the blood stream when we fast. Fatty acids contain more than twice as much energy (9 kcal/g) as carbohydrates (4 kcal/g). As the brain cannot utilize fatty acids as an energy source (unless converted to ketones) the glycerol component of triglycerides can be converted into glucose via a process called gluconeogenesis.
Saturated triglycerides fats
These contain no double c=c bonds as the each half of the bond is attached to (saturated with) a hydrogen atom. Tropical oils (such as palm kernel and coconut) commonly contain saturated fats particularly the triglycerides lauric and myristic acids. In meats and diary products such as eggs, cream, milk and cheese the most common saturated triglyceride fats are palmitic and stearic acids. Saturated fats have more energy potential than unsaturated fats so many people regard them as unhealthier than unsaturated fats but this is not necessarily true. The confusion lies in the fact that most animal fats are saturated such as cream, cheese, butter, meat products such as sausage, burgers, hot dogs and pies. Unlike plant oils, which usually contain healthy polyphenols these products usually also contain cholesterol and their cooking process often generates carcinogens such as heterocyclic amines and polycyclic aromatic hydrocarbons. Clinical studies have shown that higher intake of meat saturated fats have a much greater impact on triglyceride and cholesterol levels and heart disease than plant saturated fats which are a useful source of energy, provided you don’t eat too many, otherwise they will also contribute to weight gain.
Unsaturated triglycerides fats
These are usually categorised into monounsaturated (containing one double carbon bond) and polyunsaturated triglycerides (containing more than one carbon bond) often referred to as PUFA’s. Monosaturated triglycerides have their glyceroles component linked with omega 7 or 9 fatty acids and polyunsaturated triglycerides linked with 3 or 6 fatty acids. People often refer to triglycerides only by their fatty acid element e.g. 3 omega fatty acids without mentioning the common glycerol element making them triglycerides. The common types of fatty acids include:
Omega 3 fatty acids
These fats are essential for the healthy function of the body. They cannot be synthesised by us, so they have to be ingested regularly (like vitamins) and hence the name essential fatty acids. Convention separates them into short chain and the more biological active long chain varieties:
Short chain omega 3 – alpha-linolenic acid (ALA) and eicosatetraenoic acid (ETA) are found in plant oils such as walnuts, edible seeds, clary sage, algal oil, flaxseeds and flaxseed oils, sacha inchi, echium and hemp oils.
Long chain omega 3 – eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are found in algae, edible seaweed, phytoplankton, oily fish such as herring, mackerel, salmon, menhaden and sardine as well as cod liver, squid, krill and other marine foods. DHA is the primary structural component of the human brain, skin and retina.
Omega 6 fatty acids
Most dietary omega-6 fatty acids originate from vegetable oils, nuts, grape seed oil, soya, flaxseed and oily vegetables such as avocado. Linoleic acid, the shortest-chained omega-6 fatty acid, is an essential fatty because the human body cannot synthesize it. The other omega 6’s can be found in smaller amounts in foods including evening primrose oil, borage oil, and black currant seed oil and include gamma-linolenic acid (GLA), Di Homo gamma linoleic acid (DGLA) and Arachidonic acid (AA). These later three omega 6’s are generally synthesised by the body.
As well as a useful source of energy, omega 6’s are reported to help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system. Linoleic acid is converted to GLA, which is then metabolised further to either AA or DGLA. AA is the precursor that is metabolized by various enzymes to a wide range of biologically and clinically important eicosanoids and its metabolites, which are essential in the inflammatory process. In particular, AA can be metabolized, by cyclooxygenase 1 & 2, into prostaglandin A2 and G2 and other inflammatory cytokines including prostacyclin and thromboxanes. The enzyme 5-lipoxygenase also breaks down AA into leukotrienes, which are powerful local triggers of the immune cascade and inflammatory response such the release of histamine and recruitment of mast and killer cells.
The enzymes used to convert short chain omega 6 (linoleic acid) into long chain omega 6’s (GLA, DGLA and AA) are actually the same as those required to convert short chain omega 3 (ALA) to long chain omega 3 (EPA). Too high an intake of short chain omega 6 and too little long chain omega 3 could therefore, potentially lead to deficiency in the enzymes required to form long chain omega 3’s which are regarded as more biological active and healthier for the body. It is therefore important to consider diets with good ratio of long chain omega 3 to omega 6 vegetable oils, with ample amounts oils from algae, edible seaweed, phytoplankton, oily fish and other marine foods.
Because of this competition with enzymes effecting omega 3’s and importance of omega 6 in the immune process, it is widely quoted that omega 6’s are pro-inflammatory and as a consequence could potentially promote illnesses related to chronic inflammation, heart disease, cancer diabetes etc. There are some reports, amoung people with hyper-immune syndromes like asthma and rheumatoid arthritis, evidence that at higher omega 6 diet can exacerbate symptoms. Otherwise clinical evidence for omega 6 being pro-inflammatory is, at best, circumstantial. In fact, a healthy inflammatory pathway will be more efficient in detecting how and when to appropriately respond to trauma and infection but also to when to turn off when the risk has resolved. Omega 6 is essential for a healthy immunity as AA is metabolized to both pro-inflammatory and anti-inflammatory eicosanoids during and after the inflammatory response, respectively. Furthermore, GLA and DGLA actually reduce inflammation especially if there are no deficiencies in our essential nutrients required for good enzymatic function (including magnesium, zinc, and vitamins C, B3, and B6) that helps promote the conversion of GLA to DGLA. That is why increased consumption of omega 6 in laboratory studies has not actually been shown to cause inflammation during normal metabolic conditions unless lipid peroxidation products are mixed in.
In support of this, most, well conducted trials show that omega 6’s including AA are not carcinogenic. In fact the two largest studies which measured serum omega 6 (an analysis of the Health professionals follow up study and the SELECT study) both showed that higher serum omega 6 actually led to a lower rate of prostate cancer.
Furthermore, arachidonic acid (AA) is one of the most abundant fatty acids in the brain, and is present in similar quantities to omega 3 (DHA). The two account for approximately 20% of its fatty acid content. AA also activates syntaxin, a protein involved in the growth and repair of neurons, and limited trials have found an improved intellect in children with adequate intake. Clinical trials are ongoing giving extra omega 6 & 3 for dementia and other neurodegenerative disorders.
In terms of sport and exercise performance, AA is also metabolized eicosanoids during and after physical activity to promote growth and muscle repair via conversion to prostaglandin (PGF2alpha). Researchers from the University of Tampa reported that AA increased lean body mass, strength, anaerobic power and exercise performance in a study involving experienced resistance-trained men.
Similarly, a meta-analysis from Cambridge University looking for associations between heart disease risk and individual fatty acids reported a significantly reduced risk of heart disease with higher levels of both long chain Omega-3 (EPA and DHA) and Omega-6 (AA). A scientific report from the American Heart Association has also found a favorably health impact of dietary omega-6 fats, including AA and consequently the group does not recommend limiting omega 6 essential fatty acids.
Ensuring a good balance of polyunsaturated fats.
It is clear from the scientific (rather than the lay literature) that we should not be avoiding foods rich in omega 6 as they are healthy and beneficial. As just mentioned, The American Heart Association recommend individuals follow a diet to maintain sufficient intake levels of both omega-3 and omega-6 fatty acids for optimal health which in practical term mean at least 10% of calories coming from omega-6 fats. The trouble with a typical western diet it that is becoming increasingly low in omega 3, especially the long chain forms. As consequence the ration of omega 3 to 6 is changing to as much as 10-20:1 when ideally they should be 3-4:1. The best way to improve this ratio is to eat oily fish, or krill 2-3 times a week as part of a regular balanced diet.
Omega 7 fatty acids (monounsaturated)
The main omega 7’s in nature are mainly palmitoleic acid and vaccenic acid which are found in macadamia nuts and sea buckthorn and a lesser extent avocado fruit. They have been shown to increase insulin sensitivity and suppress inflammation.
Omega−9 fatty acids (Monounsaturated)
These are found in both animal and vegetable oils. The two most common omega−9 fatty acids are:
- Oleic acid found in olive, avocado and macadamia nut oils
- Erucic acid found in rapeseed, wallflower and mustard seeds
In addition to being a useful source of slow release energy, increased intake of monounsaturated fats help lower blood levels of Low Density Lipoprotein (LDL – bad cholesterol) and proportionately raise blood levels of High Density Lipoprotein (HDLP-good cholesterol) hence why they are associated lower heart attack risks. These oils are also rich in healthy polyphenols, which help with the production of anti-oxidant enzymes and have other anticancer benefits. In particular, the lignans and secoiridoids in olive oil have direct inhibitory activities on the tyrosine kinase activity of the HER2 gene suggestion it would be helpful in women with over-expressing HER breast cancers.
These are man made in a process were unsaturated vegetable oils are partially hydrogenated to produce saturated fats. This alters the melting point and freezing points, which make them useful for margarine, snack foods, packaged baked goods and frying fast food where they are widely used. Apart from energy, trans-fats have little nutritional value and have been shown to consistently be associated with increased risk of heart in part by raising levels of LDL and lowering HDL. Fortunately, awareness on their health risks and pressure on the food industry is reducing their use.
Cholesterol is a sterol (modified steroid) that is essential structural component of animal cell membranes. They are not needed by plants to maintain membrane structural integrity and fluidity. Cholesterol also serves as a building block for the biosynthesis of steroid hormones such as testosterone, bile acids and vitamin D.
Although normal levels are important, increased levels in the body are linked increased risk of heart disease, stroke, dementia, other neurodegenerative disorders, cancer development and its progression after diagnosis.
Absorption and secretion of cholesterol: Cholesterol can be absorbed directly from the gut from animal sources or can be made by many cells in our body particularly those in the liver with the help of the enzyme HMG-CoA reductase (the target for statins). To a certain extent, the body compensates for absorption of additional cholesterol by reducing cholesterol synthesis. In addition, cholesterol are regulated via the gut as it is either recycled or excreted in the small intestine. Every day, up to 1g of cholesterol enters the gut. This cholesterol originates from the diet, bile, and desquamated intestinal cells, and can be metabolized into a non-absorbable sterol that is excreted in the feces by a cholesterol-reducing bacterium origin has been isolated from human feces. The liver excretes it in a non-esterified form (via bile) into the digestive tract, which can be reabsorbed. Typically, about 50% of the excreted cholesterol is reabsorbed by the small intestine back into the bloodstream. This balance of absorption or excretion can be affected by the host genetic makeup, the health of the gut bacteria, level of stress and chronic inflammation and polyphenol intake (see below).
Transport of cholesterol: Cholesterol is transported around the body in lipoproteins. The total level, measured in the blood stream should ideally be less than 5mmol/L for healthy adults or less than 4mmol/L or people with a high cardiac risk such as angina, know heart disease, peripheral vascular disease, diabetes or even a strong family history. A lipoprotein with a low protein: cholesterol ratio is called a low density lipoprotein (LDL), one with a high protein: cholesterol ratio is a high density lipoprotein (HDL):
- high-density lipoprotein (HDL)– carries cholesterol away from the cells and back to the liver, where it’s either broken down or passed out of the body as bile; for this reason, HDL is referred to as “good cholesterol”, and higher levels are better (1mmol/L or more).
- low-density lipoprotein (LDL)– carries cholesterol to the cells that need it, but if there’s too much cholesterol for the cells to use, it can build up in the artery walls, leading to disease. For this reason, LDL is known as “bad cholesterol” and it is better to have lower levels (3mmol/L or less).
Factors that affect cholesterol levels
Eating far too much cholesterol and high energy saturated fats are the most usual way to raise cholesterol levels as the body simply cannot excrete it fast enough and therefore has to find areas to store it via LDL such as in the liver, soft tissues or walls of arteries. Imbalances in the production of cholesterol and re-absorption / excretion gut circulation pathways can also significantly influence serum cholesterol levels. The environmental, dietary and biological factors that we can control, through our daily lifestyle choices, are now discussed in more details:
- Excess energy intake
- High cholesterol intake
- Low polyunsaturated fatty acid intake
- Low physical activity
- High processed sugar intake
- Chronic inflammation
- Poor gut microflora
- Low polyphenol rich food intake
- Low dietary intake of plant sterols
Tips to improve the fat profile in our bodies:
All fats are energy rich, so too much intake compared to energy use via exercise, can lead to over storage of energy resulting in obesity, fatty liver and hardened arteries leading to heart disease, cancer and a multitude of deliberating chronic diseases. Cholesterol and saturated fats have the highest energy potential. Transfats have high energy but not other nutritional value. As mentioned above the omega triglycerides have numerous other healthy attributes. As a general rule we need to reduce animal saturated fats, cholesterol, eliminate transfats and increase polyunsaturated (Omega 3&6) and monounsaturated (omega 7&9) fat intake within the limits of our energy needs. There following section provides dietary and other lifestyle tips to help achieve this:
Increase the proportion fats from plant sources:
Linseeds (flax seeds) and the healthy oil it produces have a very high percentage of unsaturated to saturated fats. It also contains a high percentage of omega-3 content, six times richer than most fish oils albeit in the short chain form (alpha-linoleic acid) with a 3:6 ratio of approximately three to one.
Avocado have the highest oil content of all fruits and most of this is unsaturated, mainly monounsaturated and omega-9. Other natural sources of healthy fats include rapeseed oil, which is cheap and convenient, as it can be grown in northern European countries.
Nuts almost all contain a good percentage of unsaturated fats but walnuts are one of few nuts that contain appreciable omega-3, with approximately a 1:4 ratio.
Kiwi fruit has an even better ratio of omega 3:6 but there are only small quantities of oil in kiwi’s as opposed to linseeds.
Seeds such as pumpkin seeds have a high percentage of unsaturated fats (90%) and a good ratio of omega 3:6 (3:1) but pumpkin oils are easily damaged by heating.
Microalgae are rich sources of the longer chain omega-3 fatty acid (EPA and DHA) and can be produced commercially in bioreactors. This process may be the answer to supplying the future populations of the world with enough omega-3 and is the only source of DHA acceptable to vegans. Brown algae (kelp) is also an excellent source of EPA.
Other plant based foods with a good ratio of omega 3:6 include acai, seaweed, butternuts, chai sage, shiso and lingonberry. The leafy green vegetable Portulaca oleracea (Purslane) has the highest omega 3 levels of the green vegetables but this is very rarely used in western cooking. Some vegetables contain a small amount of omega 3, particularly strawberries and broccoli.
Extracted plant oils. Most oils used for cooking or salads contain a mixture of saturated and unsaturated fats. Linseeds (flax seeds) oil is healthy as it has a very high percentage of unsaturated to saturated fats. Olive and rapeseed (canola) oils have a particularly a good percentage of unsaturated fats. Sunflower, soya bean and corn oil all contain mostly polyunsaturated fats but tend to be heavily processed during manufacturing. Palm and coconuts have the highest percentage of saturated fats, which makes them energy rich but cold pressed varieties but can still be healthy. In terms of omega 3:6 ratio the best oils are linseeds, rapeseed (canola), soybean and olive oils (which also has omega-9). Oils from microalgae and kelp contain the highest DHA and EPA levels and are usually taken as a supplement rather than used for cooking. Sunflower, palm kernel, cottonseed, grapeseed and corn oil contain virtually no omega-3.
Animal sources of fatty acids
Fish: The most widely available source of unsaturated fats and the essential long chain n-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid is cold water oily fish. Interestingly, however, fish do not synthesize them; they obtain them from the algae and plankton they eat. Fish with the highest levels include mackerel, salmon, herring, anchovies, pollock, shark, swordfish, sardines and to a lesser extent tuna. These fish have a profile of around seven times as much n−3 as n−6. Consumers of oily fish should be aware of the potential presence of heavy metals such as mercury, cadmium (from discarded batteries) PCB’s, dioxin. As these accumulate in the food chain larger fish such as shark and sword fish have the highest levels. It is suggested that their intake should be limited to twice a week (which is still more than the majority of people currently consume in a western diet). However, after extensive review of the evidence the Harvard’s school of Public Health, reported in the Journal of the American Medical Association that the benefits of fish intake generally far outweigh the potential risks. Contamination is even lower in white, sea fish such as bass and bream, and no limits have been set on their consumption, although these have lower omega-3 levels. Freshwater fish such as trout and lake varieties are almost completely free of the potential heavy metal contamination and have good levels of omega3. Some protection from mercury contamination can be gained from eating foods rich in selenium (brazil nuts, crab meat) and this metal can bind to the mercury and stop it being absorbed into the body.
Fish oil supplements: Fish oils are particularly rich in long chain omega 3 fatty acids (EPA & DHA) and are also a good source of the fat-soluble vitamins A, D, E and K. Cod liver oil is also rich omega 3’s but there are some concerns that the vitamin A content is too high. Excess vitamin A, over long periods, can lead to health problems. It is, therefore, better to take whole fish oils rather than cod liver oils. Good quality fish oils also contain phospholipids that improve omega 3 absorption. In addition, they also contain an antioxidant called astaxanthin which helps keep the oil protected from oxidation. Bad quality fish oils can be contaminated by heavy metals such as cadmium, mercury and arsenic as they use larger fish such as swordfish, king mackerel and large tuna. Fortunately, most fish oils have not been found to contain these heavy metals, especially those that are made from smaller fish such as salmon, herring, mackerel, anchovies and sardines. Likewise some supplements have been found, by the consumer watchdog consumerlab.com, to contain dioxins and polychlorinated biphenyls (PCBs) as they use fish from polluted seas or again larger fish which are higher up the food chain. Furthermore, if exposed to heat, oxygen and light via a process call lipid peroxidisation, they form reactive oxidative species such as thiobarbituric acid that can potential damage our cells, although no reports of this have been found in humans. Nevertheless, it important to store fish oils in a cool dark place and consume well within the use by date.
Meat: Most meat is high in cholesterol and saturated fats. Being vegetarian will reduce the intake of these fats but measures have to be made to increase protein omega 3 and vitamin B12 from other sources. If you eat meat it should be regarded as a luxury rather than a standard for every meal. Consider reducing meat to 2-3 times a week and choosing quality over quantity. Processed meat usually has even more fat and unhealthy additives such as sugar, salt and preservatives. If you eat meat try to go for grass-fed animals, particularly game, more which have more n−3 than do grain-fed animals. Studies suggest that the evolutionary human diet, rich in game animals, seafood provided much higher ratio of omega 3 to other fats. In most countries, commercially available lamb is typically grass-fed, and thus higher in n−3 than other grain-fed or grain-finished meat sources but in some countries lamb is finished (i.e. fattened before slaughter) with grain, resulting in lower n−3. Chickens which roam around eating grass, worms and insects as well as grain generally have much higher omega-3. Seal oil is one of the best source of animal long chain omega 3 EPA, DHA however, it is not allowed for import into the European Union.
Eggs: They can be a good source of omega 3 (mostly ALA) and protein but only if produced by chickens fed a diet of greens and insects rather than chickens fed corn or soybeans. Like the meat, in addition to feeding chickens insects and greens, fish oils may be added to their diet to increase the amount of fatty acid concentrations in eggs. The addition of flax, chia and canola seeds to the diet of chickens, both good sources of alpha-linolenic acid, increases the omega-3 content of the eggs but this is very rarely done for mass produced chicken eggs.
Milk and cheese: These are energy rich so not good it you are struggling to loose weight. The lactose in milk is rapidly broken down to glucose and galactose so does increase glucose levels (high glycaemic index). Some people also develop intolerance to lactose especially as they get older, which can cause inflammation and gut problems. Nevertheless, milk from grass-fed cows can also be good sources of omega-3. One UK study showed that half a pint of milk from grass feed cows provides 10% of the recommended daily intake of ALA, while a piece of organic cheese the size of a matchbox may provide up to 88%. One UK company is now producing premier cheese which is made only from milk from cows which have grasses on the first spring grass.
Physical activity: Cholesterol is an excellent energy source especially, useful to individuals participating in regular exercise. Exercise has been shown not only to help weight control but lower serum triglycerides, total cholesterol and improve the ratio of high-density lipoprotein to low-density lipoproteins. Furthermore, there is evidence, that even before weight reduction occurs, exercise directly lowers excess serum testosterone, oestrogen and leptin levels and raises adiponectin levels independent of weight loss all of which have a favourable effect cholesterol pathways.
Processed sugar: People do not normally associate sugar with cholesterol but they could not be further from the truth – it is now one of the main reasons for high cholesterol. A number of well-conducted cohort studies have strongly linked higher processed sugar intake with higher serum cholesterol and heart disease. Not withstanding the influence of sugars on obesity, the two explanations of why sugar increases cholesterol are firstly that the peaks and troughs of insulin levels signal the metabolism into believing it needs to store more energy so decreases excretion of cholesterol and increases reabsorption. The second explanation, expanded below, is that sugar leads to increased expression of inflammatory markers including 12-lipoxygenase (12-LOX) and its arachidonate metabolites (see below). The most convincing study, published in the Journal of the American Medical Association, analyzed the dietary habits of a cohort 6110 Americans and showed that, after several years, those who eat more than 10% of their daily calories as sugar had significantly raised triglyceride levels, lower HDL and higher LDL cholesterol levels.
Abnormal gut bacteria: As mentioned above, cholesterol in the gut originating from bile, and desquamated intestinal cells, can be metabolized into a non-absorbable sterol that is excreted in the feces by a cholesterol-reducing bacterium origin has been isolated from human feces. Typically, about 50% of the excreted cholesterol is reabsorbed by the small intestine back into the bloodstream. Research presented at the American Heart Association’s reported that abnormal gut bacteria reduce the natural excretion of cholesterol and increase serum levels. They have also reported that a formulation of Lactobacillus in a nutritionals supplement may be able to reduce blood levels of LDL (bad cholesterol).
Chronic inflammation: Although an inflammatory response is an important part of a healthy innate immunity, persistent low-grade increased chronic inflammatory activity is associated with uncomfortable symptoms including fatigue, joint pains, abdominal bloating, cognitive impairment and anxiety. As well as raised inflammatory markers in the blood stream chronic inflammation raising blood sugar and cholesterol levels and hence it is associated with a greater incidence of age-related diseases such as Alzheimer’s disease, cancer, arthritis, type two diabetes, atherosclerosis, heart disease and stroke. The reason chronic inflammation increases the cholesterol (and sugar) levels is the body thinks it is under attack. This triggers stress, flight and flight pathways so preserves as much energy as possible (making more cholesterol and blocking excretion in the gut. The factors that increase chronic inflammation in the body (pro-inflammatory) include sedentary behaviour, obesity, sugar intake, exposure to environmental of ingested toxins. Factors that reduce in inflammation (anti-inflammatory) in the body include regular exercise, polyphenol rich diet and healthy bacteria intake within a macrobiotic diet or probiotic supplements.
Phytosterols are structurally related to cholesterol. Plants manufacture phytosterols, which can compete with cholesterol for reabsorption in the intestinal tract, thus potentially reducing cholesterol reabsorption. When intestinal lining cells absorb phytosterols, in place of cholesterol, they usually excrete the phytosterol molecules back into the gut, an important protective mechanism. Sitosterol and campesterol are the most frequent plant sterols and constitute about 60% and 35%, respectively, of plant sterols in food. Plant stanols, are the saturated form of plant sterols, meaning they have no double bond in the sterol ring. Saturated sitosterol is known as sitostanol and saturated campesterol is campestanol.
Plant foods that are particularly rich in phytosterols (stanol or sterol esters) include avocados, flax seed, peanuts, soy beans, chickpeas, quinoa, pumpkin seeds, beans and buckwheat but are also found in whole grains, vegetables, fruits, nuts and seeds. Regular intake of these foods is linked to lower serum cholesterol levels as highlighted in a recent meta-analysis of 41 trials. From these data it appeared that 2-3 g/day seemed to be the optimal amount to reduced low-density lipoprotein (LDL) by about 10% and higher intake of sterol esters did not seems to reduce cholesterol further. The beneficial effects, however, were found to be additive with other lifestyle interventions. For example, eating foods low in saturated fat and cholesterol and high in phytosterols reduced LDL by up to 20% and eating them with statin medication almost doubled their cholesterol lowering capacity. In addition, a growing body of scientific evidence also suggests other positive health outcomes that include the reduced risk of certain types of cancer. Although further research is needed to determine whether this reduction in LDL will lead to a reducing in heart attack, numerous organisations are promote their intake as a therapeutic option including the American Heart Association (AHA) Spanish Cardiology Society, the Association of Clinical and Public Health Nutritionists in Finland, and the National Heart Foundation in Australia.
Plant sterol and stanol fortification and supplements: A dietary supplement is, regarded by many, as a convenient way to boost daily plant sterol intake, especially those who do not like eating these foods. Some yogurts also have small quantities of sterols added but many of these products also contain added sugar and flavours. The studies above show they could lower cholesterol by 20% especially if combined with other lifestyle measures and thus may be enough to reduce their future cardiovascular risk and mitigate the need for statins. Sterol supplements would also be very useful for individuals who are already taking statins but are are suffering side effects as studies show they enhance their LDL lowering effects. Instead of stopping statins altogether, people with side effects may be better off lower the statin dose and take a concomitant plant sterols supplement at the same time. This compromise may be enough to stop side effect and maintain a normal serum cholesterol. There are some safety issues related to very high intake of plant esters sterols (>3g / day). This high intake could increase serum plant sterol levels, which some argue may potential increase artherosclerosis. This risk is largely hypothetical, and any increase due to the small increase in plasma plant sterols is more than offset by the decrease in plasma LDL. The reality is that, in a western diet, the consumption of plant sterols is usually very much less than 0.5g / day so individuals can safely be advised to eat considerable more of these foods and even take a sterol supplement. Another potential concern with very high doses is that they could potentially affect the absorption of cartenoids and fat-soluble vitamin. This can, in theory, constitute a hazard to children, pregnant and breastfeeding women. Because of this theoretical risk, labelling, therefore, advises these individuals to avoid consuming these products. Despite this theoretic risk, meta-anlaysies have not demonstrated lower vitamin A, D, E and K levels after plant sterol intake. Nevertheless, general advice if taking a sterol or stanol supplement is to ensure adequate intake of carotenes rich foods such as carrots, pumpkins, squash, broccoli, apricot and mango. As an added precaution, nutritional supplements and functional foods can be enriched with saturated, less absorbable plant stanol esters which not only reduce serum cholesterol on their own, they also reduce plant sterol levels in the blood stream. The safety and efficacy of plant stanol esters have been confirmed in more than 70 published clinical studies which show that daily intake of 2 g plant stanols as plant stanol ester lowers LDL-cholesterol by 10%, on average. They are now widely recommended dietary measure to reduce serum cholesterol from a number of academic bodies including the American Heart Association. In Europe, foods with added plant stanol ester have been on the market for 20 years, and today such products are also available in many Asian and American countries. For optimal cholesterol lowering aiming at a lower risk of cardiovascular disease, plant stanol ester should be used daily, in sufficient amounts, with a meal and in combination with other recommended dietary changes.
Other general issues with the cooking, storage and eating of fats
It is necessary to process oils in order to bottle and store them on the shelf. Heating oils, however, tends to damage the unsaturated fatty acids particularly the omega-3 and increases the percentage of saturated varieties not to mention increase the levels of hydrocarbons and acrylamides. Pumpkins seed oil for example contains little omega-3 despite the pumpkins seed itself being a rich source. Cold pressed oils are the best, of which olive oil is the most popular which contains high quantities of omega-9 (Oleic acid) but only low to moderate amounts of omega 3 and 6. Heating this up in a frying pan, however soon damages the healthy fats. It is better to use plant saturated oils when deep frying such as sustainably sources palm oil as it is more resistant to oxidization and has a higher smoke point than polyunsaturated oils. Other good examples are avocado oil, peanut oil, rice bran oil. Olive oil, even cold pressed can be used for frying but when cooking it is best not to heat rapidly at too high a temperature – use a low flame and if you see smoke turn off the heat completely. Also the more often oils are reheated the higher the damage and carcinogen content.
As well as time, several factors effect the safe storage and quality of edible oils including air, heat and light. Many types deteriorate through oxidation (rancidity), a process which is greatly enhanced when edible oils are stored in containers that are not air tight and in areas where the oil is exposed to heat and light. If improperly stored, some oils can easily take on other flavors. In this case, an unpleasant smell or taste indicates that the oil is no longer desirable for consumption. A wine smell or taste may reveal that the oil was not stored properly. A metallic flavor indicates that the oil was stored in a container made with reactive metal. Most unrefined oils (oils obtained from cold pressing, mechanical methods) will keep for 3 to 6 months if properly stored in a cool dark location. The refrigerator is the best place to store unrefined oils and although most will solidify in the colder temperature, they will return to a liquid state if removed from the refrigerator one or two hours prior to use. Refined oils (oils obtained from heat and solvent extraction) tend to keep twice as long as unrefined oils – at least 6 to 12 months if stored properly. An oil high in polyunsaturated fat has a much shorter shelf life than oils high in monounsaturated or saturated fat and should be stored in the refrigerator to extend the shelf life.
Cooking with fats:
The following tips depend on whether an individual needs the energy from fats or not. Sportsmen and women or those with physically active jobs will get a great deal of benefit from fats in foods as a useful slow-release energy source. Likewise, patients with advanced cancer or poor appetite will need to maintain their fat intake. For most of us, who need to reduce our energy intake or reduce our cholesterol levels, these tips apply:
As far as possible aim to gently grill, bake, poach or steam food rather than deep frying or roasting. Measure oil with a tablespoon or use an oil spray, rather than pouring it straight from a container. Spoon off fats and oils from roasts and likewise when booking with mince (Spaghetti Bolognese, chili con carni etc) use a lower-fat mince, brown the mince first, then drain off the fat before mixing other ingredients. When making casseroles, stews, pies or curries put more vegetables or beans and less meat. A good trick is to use soya meat substitute instead or even mix half and half – most people will not even notice. Try to cut out meat or restrict to 2-3 times a week, choose lean cuts from animals that have been grass fed or game such as venison and pheasant. Processed meat products such as bacon, sausages and pies invariably use cheap fatty meat with added salt and sugar. Likewise choose eggs, cheese and milk from free range animals and prepare without oil or butter such as poached, boiled or dry fried. Avoid yoghurt with added sugar yoghurt and use live verities. When roasting potatoes, cut them into larger pieces than usual and using just a little sunflower or olive oil. When making sandwiches, try leaving out the butter or if necessary use reduced-fat spreads, such as olive oil or sunflower spreads (avoiding trans fats). If adding cheese try a strong-tasting cheese, such as mature cheddar or stilton because you’ll need less. If you’re making your own chips use the thick varieties and cook them in the oven with a little sunflower oil, rather than deep frying.
Choosing foods when out and about:
Convenient online delivery companies are making it even easier to order good value cooked food. Together with an increasing choice of outlets in the high street less people are preparing food at home, especially young professionals. Though this adds more free recreational time, hopefully used to exercise, this provides less control on the quality of ingredients, especially the quality of the fats used and whether foods have been fried in fats, which have been repeatedly, heated and reused. There are some general rules to follow which may reduce their unhealthy fat content:
Choose a lower-fat topping for pizza, such as vegetables, ham, fish or prawns, instead of pepperoni, salami or extra cheese. Choose thick, straight-cut chips instead of french fries or crinkle-cut. Try to avoid meat as it will inevitably be cheaper cuts and from mass produced farms. Particularly avoid processed meats. If possible choose whole meal pasta and a tomato sauce rather than a creamy or cheesy sauce. In the kebab shop, go for a shish kebab with pitta bread and salad, rather than a cheaper more fatty doner. Curries can be very healthy and tasty but go for dry or tomato-based dishes, such as tandoori or madras, instead of creamy curries, such as korma, pasanda or masala. Choose rice and chapatti instead of naan. Likewise in the Chinese restaurant or takeaway, choose a lower-fat dish, such as steamed fish, chicken chop suey or Szechuan prawns. Thai food usually has even less fat but still go for stir-fried or steamed dish containing chicken, fish or vegetables rather than beef or pork. Watch out for thai curries that contain coconut milk, which is high in fat. If you choose one of these, avoid eating all the sauce. In the coffee shop try to swap any large whole milk coffee ones with less milk such as a flat white or cortado and don’t be tempted by the usual extensive range of fatty and sugary cakes, Danish pastries and donuts. Overall, it is much better not to snack between meals – to give your stomach, gut and pancreas a rest from digestion. Ideally your stomach should be empty when you start your next meal. Drops in blood sugar below normal will not happen unless you had a very sugary meal, in fact slow release energy sources such as healthy fats with help maintain blood sugar without the peaks and troughs. Sugary snacks should definitely be avoided between meals as these will increase your insulin levels the then drop them below normal half an hour later making you tired and hungry. If you do need a snack try nuts, pumpkins seeds or whole meal bread. If you need something more, try a small piece of 100% sugar free chocolate with a piece of fruit – tasty, super healthy and the polyphenols and caffeine will provide the extra life you may be seeking.
Summary – Practical tips to reduce serum cholesterol and increase polyunsaturated fats
Ensure a healthy energy balance
- Don’t over eat
- Try to fast 13 hours overnight
- Try not to snack between meals
- Reduce animal saturated fats and cholesterol intake
- Be more physically active
- On days in which you are sedentary eat less and on active days eat more.
Reduce processed sugar or refined carbohydrate intake
- Stop adding sugar to tea or coffee
- Change to sugar free cereals in the morning
- Although whole fruit is good – dried fruit or fruit preserves in sugar should be avoided
- Cut out sugary sweets, cakes, biscuits particularly on an empty stomach
- If you fancy something sweet – restrict to after a meal
Increase the proportion of unsaturated (polyunsaturated and monounsaturated) fatty acids:
- Oily sea fish – mackerel, herring, swordfish, salmon, sardine
- Other white sea fish – cod, sea bass and bream
- Algae, krill and brown algae (kelp)
- Fresh water fish – lake varieties, trout and river salmon
- Seeds – Linseeds (crushed), sunflower, sesame and pumpkin seeds
- Walnuts, almonds, Brazil nuts, peanuts, pine, cashews, hazel and macadamia nuts
- Meat from wild game or animals fed on grass
- Dairy and eggs from free range animals fed on grass or natural foraging
- Fruit – particularly avocado, kiwi fruit, strawberries and lingonberries
- Vegetables – leafy greens, hemp and broccoli.
- Herbs – Chai sage and perilla
- Cold pressed vegetable oils e.g. olive oils rapeseed (canola), soya, rapeseed (Canola) and sunflower
- Root vegetables, carrots, squashes
Decrease animal saturated fats and cholesterol intake
- Meat – particularly non grass or free range fed
- Animal fats
- Trans fats in fast foods, margarines, biscuits and cakes.
Increase plant phytosterols and stanols
- Avocados, flax seed, peanuts, soya beans, chickpeas, beans and buckwheat
- Grains, vegetables, fruits, nuts and pumpkin seeds.
- Colourful fruit – pomegranates, tomatoes, strawberries
- Cruciferous vegetables – broccoli, Brussels sprouts, asparagus
- Herbs and spices – turmeric, chili, parsley
- Teas, mushrooms, sugar free chocolate
Eat more bacteria rich foods
- Miso soup
In conclusion. Fats can be a useful source of slow release energy required for a healthy active lifestyle. Many fatty acids are essential for cell and brain development, enzyme production, are essential for a number of important cellular and immune functions. The trouble is that in the western diet we generally eat substantially too many of them for our needs. Diets that contain lower levels of animal saturated fats and have higher levels of unsaturated facts are beneficial to our health because they reduce serum cholesterol within low density lipoproteins lowering the risk of cancer, premature aging, cardiovascular disease including strokes and heart attacks. Foods that contain higher levels of unsaturated fatty acids are protect individuals from degenerative disorders such as dementia, poor eyesight and Parkinson’s disease. In addition to the guidance in this section, it would be very wise to ask your doctor to measure your lipid profile with a fasting blood test. On top of this a micro-nutritional serum profile will help you choose foods or supplement which produce the optimal balance of essential fats.
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