Lifestyle tips to help arm your body 

By Professor Robert Thomas
extracts from “How to Live


The very last thing I want to do is to blame people for their suffering which covid-19 has caused to innocent people across the World. Many fit men and women have been struck down, for no fault of their own, but the reality is that people with medical conditions do have a an increased odds of developing serious consequence of this awful virus.  The official published data  from New York, for example, showed that of the 15,230 tragic deaths from covid-19 up until May 2020, less than 1% did not have either diabetes, heart disease, high blood pressure, obesity or concurrent serious illnesses. Many of these chronic conditions are strongly influenced by overeating, unhealthy food choices, a sedentary lifestyle and other poor daily choices accumulated over many years [Mahase]. The big question, however, is whether a change in nutrition and lifestyle today will act quickly enough to influence the consequences of a recent covid-19 now?

My opinion is – Yes – This is why, with a team of likeminded scientists,  we have designed The National covid-19 nutritional intervention study. This research, due to complete recruiting in March 2020, is trying to find out whether boosting the diet with a healthy foods and  probiotic supplements could change the body in time to improve outcomes from a covid-19 infection. This trial will hopefully produce the robust data required to add to official government advice. In the meantime, this project has given me the opportunity to talk to,  and learn from, over 500 men and women who have suffered the consequences of covid-19 in order to recruit them into this intervention. In addition, the more I have delved into emerging data from around the world, required for the trial design, the more I am convinced that lifestyle factors have profound effect, not only on the risk of chronic disease later in life, but the risks of an infection today.

Summarising this research and taking personal experiences into consideration, here are my 10 informed tips. Hopefully, they can act as  a focus for sensible self-help strategies but of course they should not be regarded as alternatives to  government preventative guidance and vaccinations:

Weight excess

Even though it takes several months to start seeing significant weight reduction, even with the best exercise and calorie restrictive diets, the usual lifestyle measures taken to help weight loss have immediate effects. In particular, reducing calories, and increasing physical activity reduces excess inflammation, reduces excess oestrogen levels and elevates levels of a molecule called adiponectin that directly protects the linings of the airways.

[Lifestyle Tips to help with weight loss].



As well as helping with weight reduction, a combination of resistance and aerobic exercise increases the muscle to fat ratio which is known to improve immune efficiency [Al-Attar]. It also helps make the blood less sticky, reducing the risks of blood clots which are more common after a covid-19 infection. It improves lung function and helps clear debris and mucous especially if exercise is performed at a reasonable intensity.

[Tips to help you exercise safely].



Even though damage may have already been inflicted on the lung through years of irritating smoke, quitting still has immediate benefits – haemoglobin is not laden with carboxy compounds in smoke, so oxygen levels in the tissues increases. Likewise, blood gets less sticky so the blood clot risk is reduced.

[Tips to help you quit].

Vitamin C and citrus bioflavonoids

The European Food Standards Agency (EFSA) and other academic bodies that Vitamin C contributes to the normal function of the immune system [Naidu]. More specifically, a recent study involving patients with covid pneumonia showed that vitamin C helped to increased tissue oxygenation [Holford]. The mechanism for this is that vitamin C and natural chemicals called citrus bioflavonoids aids the conversion of natural nitrates, rich in foods such as celery, pomegranate, beetroot and leafy green vegetables into nitric oxide which dilates vessel improving blood flow [Thomas]. Citrus bioflavonoids have also demonstrated inhibitory effects on various viruses including influenza and even SARS-CoV infected cells [Ryu]. Try to ensure a daily intake of fruit, vegetables and nuts and if you take a vitamin C supplement make sure it includes bioflavonoid

[Read more about vitamin C supplements]

Vitamin D

Diet Lifestyle and CovidThere are multiple health benefits of maintaining adequate vitamin D levels ranging from bone, density, calcium regulation, cancer, mood and arthritis [Thomas] but in terms of covid-19, it is known that people with subnormal levels of vitamin D also have a risk of immune dysfunction [Pereira]. This was highlighted in studies that showed that people with low levels of vitamin D had a higher risk of cold and flu but reassuringly interventions which involved taking extra vitamin D supplements reduced the risks [Pereira]. During the dark winter months it would be a sensible precaution to take extra vitamin D3 supplementation around 1000iu / day or more if you suspect a pre-existing deficiency. There is also evidence that taking a lactobacillus probiotic with vitamin D could improve absorption and increase blood levels [Jones].

[Tips to improve vitamin D levels].

Avoid vitamin A&E supplements:

Although, vitamin C, D and whole food polyphenol rich supplement are safe the same cannot be said for vitamin A&E containing supplements. Unlike polyphenols which promote a natural adaptive increase in anti-oxidant enzymes in times of oxidative stress, direct anti-oxidants (vitamin A and E) can actually block this process [Thomas, Millar, Dundar]. So, in the long term, this leads to greater oxidative stress. Excess oxidative stress can increase damage to cells [Poljsak, Avery]. Unless you are known to have a deficiency in vitamin A & E it is best to avoid extra supplement but instead rely of whole foods such as carrots, leafy green vegetables and oily fish.

[Read more about supplements to avoid].

Probiotic (healthy bacteria) and gut health.

There is a critical and complex relationship between the immune system and the trillions of microbes in the body, especially the gut and linings of the lung. The biodiversity of the bacteria in our bodies (microbiome) deteriorates with age, obesity, poor diet, high sugar intake, sedentary behaviour and low intake of bacteria and polyphenol rich foods [Gill]. The reduction in protective healthy bacteria leads to inflammation of the gut wall, increasing its permeability (leaky gut syndrome) and allowing an influx of toxins into the blood, which triggers abnormal chronic inflammation that in turn causes damage to joints, muscles, the heart and brain [Sanders, Keep-healthy]. It has also been shown previously that dysbiosis of gut microbiota make an individual more susceptible to respiratory conditions including viral infections [Fanos, Dang Hufnagl, Wang]. In my experience, many patients admitted to hospital with covid have a long history of symptoms associated with poor gut health. Other doctors, also managing patients with covid, have also reported similar findings [ Mukherjee, Fanos].  Conversely, published research has shown that patients with more severely affected respiratory symptoms often have gut symptoms for many months [Smyke, Wan]. Ways to increase the ratio of healthy bacteria in the gut include exercise; reducing processed sugar, eating prebiotic rich foods such as mushrooms, nuts, artichokes and beans; probiotic bacteria in live yogurt, kimchi, mature cheeses and even a good quality probiotic supplements. The full extent of the benefits for the specific blend of probiotics  in yourgut+ is being investigated in the phyto-v study and other studies across the World [Amin] but there is already trail reporting a reduction of viral upper respiratory infections from previous studies [Olaimat, Rerksuppaphol, Fujita]. In particular, a summary of all international studies was published in the prestigious Cochrane Database of Systematic Reviews, and concluded that probiotics also reduced the incidence of upper respiratory tract infections [Hoa].

[Tips to improve gut health]

Essential minerals

Zinc, magnesium, selenium and copper are essential for the formation of anti-oxidant enzymes. These enzymes are responsible for defending the cells from oxidizing chemicals. Deficiency in these minerals can lead to oxidative dysregulations – commonly seen in the lung of patients with covid [Polijsak]. There are some links between mineral deficiencies and worse outcomes from covid [Zhang]. Although here is no formal trial proving that evidence that taking extra supplements them will reduce the risks of covid it would be worth adapting dietary measures to ensure adequate intake especially as modern intensive farming, overcleaning and processing are depleting minerals from many western diets.


[Tips to increase dietary essential minerals].

Plant polyphenols, and phytochemicals

polyphenolsPolyphenols found in vegetables, fruit, legumes, nuts, herbs and spices have numerous health benefits ranging from reducing cancer, arthritis, diabetes to dementia risk [Thomas]. As regard to the immune system, although they are often said to be anti-inflammatory their mechanisms of actions are more sophisticated than that alone [Thomas]. They modulate and support crucial signalling enzymes in the inflammatory pathway including NF-kappa B which mean they enhance inflammation when needed and help switch it off when not needed [Thomas, Thomas]. Polyphenols can also help reduce excess oxidative stress within tissues via their ability facilitate activation of the transcription factor NF‐E2–related factor 2 (Nrf2), which enhances an appropriate antioxidant response to damage [Stivala, Davidosn, Juge, Dinkova‐Kostova). Many polyphenol rich foods also have roles as prebiotics, helping to preferentially feed anti-inflammatory (healthy) gut bacteria. These are all important factors which can influence the severity of a covid infection [Messini]. Remarkably, laboratory experiments have also reported these gifts from nature have direct anti-viral properties including flu and SARS-associated coronavirus infections [Li, Lin, Ge, Wu, Lau, MacKay, kotwal]. The phytochemicals with particularly robust evidence of an anti-viral attribute include ellagic acid and Epigallocatechin-3-gallate, anthocyanins, flavonoids quercetin found in pomegranate, tea, onion and red wine; Curcuminoids found in turmeric;   Apigenin rich in chamomile, parsley, celery and citrus fruits;   Aloe emodin found in aloe vera; Hesperetin and other bioflavonoids found in citrus fruit. Their anti-viral actions are multifactorial with different foods having different actions so a mixture of these food in the diet ensures synergy between them [Kaul, Kumar]. Some reduce replication rates of the virus (blocking reverse transcription), others block viral inoculation or reduce penetration of the virus through the cell wall [Park, Calland, Neu, Su,Sundararajan, Yang]. It’s important to eat these foods on a daily basis and even consider a food quality polyphenol rich supplement. The Phyto-v study is also evaluating whether boosting the diet with a whole food concentrated supplement would enhance recovery from a covid-19 infection.

[Read more about The National Covid nutritional intervention study]

Healthy fats

Polyunsaturated fatty acids (PUFAs) such as omega 3 and omega 6, found in oily fish, nuts and vegetable oils, are a good source of slow-release energy. They are required to build cell walls and play an important role in many other essential biochemical pathways. They are both required as building blocks for immune pathways so a healthy balance of these fats in the diet is important. Conversely, burnt or stale fats can cause inflammation and should be avoided.


[Tips to ensure health fat intake]

Psychological stress

Chronic stress causes a hormone called cortisol to be released by the adrenal glands. Cortisol initially reduces inflammation but in the long run chronically high levels disrupt blood sugar balance, often leading to high insulin levels, obesity and sometimes diabetes, all of which increase the wrong type of inflammatory markers. A jaw-dropping 20% of the UK population have symptoms of anxiety or depression, and on a global scale, more than 264 million people of all ages suffer from depression, making it one of the leading causes of years lived with a disability worldwide. It is easier said than done when dealing with the trauma of social isolation, home schooling and loneliness but try to get enough sleep, keep yourself intellectually stimulated and adopt measures to protect your psychological well-being.

[Tips to help mood].

Hot and cold showers:

There is some reports that hot followed by cold showers, or saunas followed by a cold bath can actually help stimulate a healthier immune response by enhancing brown fat (a special type of body fat that is activated when you get cold and  reducing the chance of catching a cold (Buijze).

[Read more about enhancing the immunity]


House plants

Growing plants indoors help keep the air humid and as clean both important factors when recovering from a chest infection such as covid-19. The air in our houses is often more polluted than the outside air as polluted air from outdoors can get trapped inside, and this is added to contaminants from inside our own homes, predominantly Volatile Organic Compounds (VOCs) which are emitted from cleaning products, paint and furnishings (Gubb). A NASA clean air study found that many plants are very effective at removing VOC’s. Some plants such as English Ivy can also reduce the amount of airborne mould which can irritate the airways of some sensitive individuals.  Plants also ‘breathe’ in the opposite way to humans, absorbing carbon dioxide and releasing oxygen through photosynthesis. The Dutch Product Board for Horticulture commissioned a workplace study , which discovered that adding plants to office settings decreases the number of colds, headaches, coughs, sore throats and flu-like symptoms among workers. Other studies have shown they can speed up recovery from a hospital procedure [Franklin, Fjeld, Park]. Some plants aroma can boosts mood, memory, reduce stress and increase mental alertness relevant for people suffering Fatigue and poor concentration after covid [Deng].

[Read more about the benefits of house plants]


Further reading


All this diet, lifestyle and covid advice and a lot more is highlighted, in  detail in How to Live published in September 2020 by Short Books UK. This 430 page book describes the background evidence and mechanism of how the body arms and protects itself from infections and chronic disease. It emphasises how the nutritional decisions we make every day considerably  influence the biochemical pathways is our body and how these increase the odds of illness.

[More about this book]


References for lifestyle, deit and covid:

Al-Attar A  et al. Human Body Composition and Immunity. Front Immunol. 2018;9:440.

Holford P et al (2020). Vitamin C as an adjuvant for covid infetcion. Nutrition, 12, 3760

Ryu Yet al (2010). Biflavonoids displaying SARS-CoV inhibition. Bioorg Med Chem;18:7940

Naidu K (2003). Vitamin C in human health and disease – an overview. Nutr J, 2, 7.

Thomas R (2020). Vitamin C – Citrus bioflanonoids. keep-healthy. com/vitamin-citrus-bioflavonoids

Jones M et al (2013). Lactobacillus probiotic increases vitamin D : a RCT. J Clin Endocrinol endnotes 437 Metab, 98, 2944–51.

Pereira M  et al (2020) Vit D deficiency aggravates COVID-19: A meta-analysis, Critical Reviews in Food Science & Nutrition, 10.1080/10408398.2020.1841090

Thomas R (2020). Vitamin D evidence reviewed – vitamin-d/

Grant W et al (2020) Evidence for vitamin D and covid-19. Nutrients; 2;12(4):988

Thomas R et al (2020). Oxidative and anti-oxidative stress – getting the balance right.

Miller E et al (2005). Meta-analysis: high-dose vit E supplementation may increase all-cause mortality. Ans Int Med, 142(1), 37.

Dundar Y and Aslan R et al (2000). Antioxidative stress. Eastern Journal of Medicine, 5 (2), 45–47.

Avery N et al (2003) Effects of vit E on recovery from repeated bouts of resistance exercise. J Strength Cond Res.17(4):801-9.

Poljsak B (2012) The Neglected Significance of “Antioxidative Stress” Oxid Med Cell Longev. 480895.  doi: 10.1155/2012/480895

Saunders M: Probiotics: Their potential benefit to human health. J of the council for ag science and tech 2011  Oct 2011.

Health benefits of probiotics –

Smyk W. et al (2020). COVID-19: focus on the lungs but do not forget the gastrointestinal

tract. Eur. J. Clin. Invest. 50, e13276,

Wan, Y. et al. Enteric involvement in hospitalised patients with COVID-19 outside

Wuhan. Lancet Gastroenterol. Hepatol. 5, 534–535 (2020).

Fanos V et al (2020). Lung microbiota in acute respiratory disease: coronavirus J. Pediatr. Neonat. Individ. Med. 9,  e090139,

Dang, Aet al Microbes, metabolites, and the gut–lung axis. Mucos. Immunol. 12, 843–850 (2019).

Hufnagl K et al (2020).Dysbiosis of the gut and lung microbiome has a role in asthma. Semin. Immunopathol. 42, 75–93

Wang, H. et al (2013). Gut-lung crosstalk between pulmonary and inflammatory bowel diseases. World J. Gastroenterol. 19, 6794.

Mukherjee, S et al . More of the gut in the lung: how two microbiomes meet in ARDS. Yale J. Biol. Med. 91, 143–149 (2018).

Olaimat  A et al. Probiotics and prebiotics for the prevention and treatment of COVID-19 Beijing UniversityScience of Food (2020)4:17 ;

Rerksuppaphol S et al. Randomized controlled trial of probiotics to reduce common cold in schoolchildren. Pediatrics International 2012;54(5):682‐7.

Fujita R et al. Decreased upper respiratory tract infections with daily intake of fermented milk: a multicentre, double‐blinded, RCT Am J of Infection Control 2013;41(12):1231‐5.

Gill HS et al. Dietary probiotic supplementation enhances natural killer cell activity in the elderly. J Clin Immunol. 2001;21:264–271.

Hao Q, Dong B, Wu T et al Probiotics for preventing acute upper respiratory tract infections: A cochrane metanalysis (2015)

Zhang J et al (2020) Association between selenium deficiency and covid. American Journal of Clinical Nutrition, Vol 111 (6); 1297.

Poljsak B et al Strategies for reducing o oxidative stress. Oxidative Medicine and Cellular Longevity. 2011:9

Thomas R et al. Phytochemicals in Cancer Management. Current Research in Compl and Alt therapy.  2017, 105 (01), pp 2-8.

Thomas R,  et al . Phytochemicals in cancer prevention and management? BJMP 2015, 8 (2), pp 1-9.

Kaul T et al Antiviral effect of flavonoids on human viruses. J Med Virol. 1985, 15(1):71-9.

Kotwal G. Natural anti-virals against human viruses, Virol Mycol 2014, 3:2 DOI: 10.4172/2161-0517.1000e107

Kim K  et al . Curcumin inhibits hepatitis C virus replication . FEBS Lett. 2010;584:707–12.

Kumar D et al Curcumin and Ellagic acid synergistically induce ROS generation and DNA damage Biomed Pharmacother. 2016;81:31-37. doi: 10.1016/j.biopha.2016.03.037.

Li SY, et al. Natural compounds with antiviral activities against SARS-associated coronavirus. Antivir Res. 2005;67:18–23

Lin C et al. Anti-SARS coronavirus 3C-like protease effects of plant-derived phenolic compounds. Antivir Res. 2005;68:36–42.

Lin L et al Antiviral Natural Herbal Medicines J Tradit Complement Med. 2014 , 4(1): 24–35.  doi: 10.4103/2225-4110.124335

Lin C et al Anti-SARS coronavirus of Isatis indigotica root and plant-derived phenolic compounds. Antiviral Res. 2005 ;68(1):36.

Li S et al Antiviral activity of aloe-emodin against influenza. Eur J Pharmacol. 2014 5;738:125-32.

Lu D et al Probiotics in preventing and treating chemo-induced diarrhoea: a meta-analysis.Asia Pac J Clin Nutr. 2019;28(4):701.

Lv, X et al. Apigenin Inhibits viral Replication Through Suppressing Antiviral Research 2014, 109, 30–41.

McKay D et al A review of the bioactivity and potential health benefits of chamomile tea Phytother Res. 2006;20:519–530.

Messina G et al. Functional Role of Dietary Intervention to Improve the Outcome of COVID-19:  Int J Mol Sci. 2020 ;21(9):3104.

Ge H, Wang YF, Xu J, Anti-influenza agents from Traditional Chinese Medicine. Nat Prod Rep. 2010; 27(12):1758-80.

Buijze G et al (2016). The effect of cold showering on health: a RCT. PLoS One, 11(9), e0161749.

Mahase E. Covid-19: Why are age and obesity risk factors for serious disease? BMJ 2020;371:

Deng L et al Roles of indoor plants in human health. Environ Sci Pollut Res Int. 2018;25(36):36087-36101.

Franklin PJ (2007) Indoor air quality and respiratory health of children. Paediatr Respir Rev 8:281–286

Fjeld T et al (2000). The effect of interior planting on health  among workers and school children. Hort Tech, 10 (1).

Shah U et al (2013). Health benefits of gardens in hospitals. IJERT, 02, (09);

Park S et al (2006). A RCT evaluating the influences of indoor plants in hospital rooms on health outcomes.  NEJM 333, 735.

Gubb C et al (2018). Can houseplants removing CO2 and increasing relative humidity?. Air Quality, Atmosphere & Health, 1-(11).