Coronavirus & Nutrition

This week marked the first Covid vaccinations as the death toll from the virus has long surpassed 60,000 people across the UK. There is a lot of information and MIS-information out there, but what is known so far is that in some cases the infection does not cause much disruption and in others – it can be deadly.

But why is that? What can people do beyond vaccination to improve their health and potential outcomes? How they can deal with the now widely recognised post-Covid syndrome?

I have tried to summarise below the EVIDENCE BASED RESEARCH that is out so far.

Known Risk Factors


Obesity and Metabolic Syndrome (insulin resistance, hypertension, abdominal obesity, and high blood lipids) have now been officially associated with increased risk and negative outcomes associated with Covid (1). The suspected mechanism behind the link is that obese individuals are depleted in certain vitamins and minerals such as Vitamin D (2) and this vitamin is particularly good for helping the immune system fight infection, especially respiratory infections (3).

In addition, obese individuals have higher levels of inflammation as adipose tissue ( fat cells) produce these such as Il-6, which in turn have been found to have a role to play in the induction of the so called ‘cytokine storm’ (4).

Blood Sugar Dysregulation

Research (5) points that blood sugar dysregulation such as high fasting levels WITHOUT a previous Type 2 Diabetes diagnosis is an independent predictor for 28-day mortality in patients with COVID-19. The sample size of this study was fairly large (605 patients) and the study found that patients with a Fasting Blood Levels level of 7.0mmol/l or over had more than double the risk of dying than those with a level of 6.0mmol/l or less.

Lowered Immune System

The immune system is like the army of soldiers that protects us from viruses and pathogens. The status of the immune system is dependent on various factors such as:

Nutritional Status – vitamins such as Vitamin D (again), Selenium, Zinc, Vitamin C, EPA and DHA (6).

Innate Immunity and Barriers – Innate immunity involves barriers that keep harmful materials from entering your body. Examples are your skin, certain enzymes, mucus, the tight junctions in your gut, stomach acid levels etc. If some of these are more compromised your immune system response might be compromised.

Lack of Gut Microbiome Diversity – some of the bacteria in our guts may help regulate the immune system, in fact about 70-80% of our immune system cells are found in our gut. Researchers are beginning to find a link between the diversity of our microbiome and Covid risk and outcomes (7).

Gut Dysbiosis – this term refers to microbial (between ‘good’ and ‘bad’) bacteria in your gut. Research (8) suggests that patients with COVID-19 had significant alterations in faecal microbiomes compared with controls, characterized by enrichment of opportunistic ‘bad’ pathogens and depletion of beneficial ‘good’ commensals, at time of hospitalization and at all timepoints during hospitalization.

High refined carbohydrates/sugar diet – in addition to what I discuss above about the blood sugar dysregulation, diets high in sugar (not just added sugar, but also the consumption of excess refined carbohydrates such as bread, fizzy drinks, muffins, cereal, cakes etc.) has been found to suppress the immune system for over 5 hours (9). The amount used in the research is 75 grams, which sounds like a LOT, but in fact you will get that much sugar from about 600 ml bottle fizzy drink!

Nutraceuticals, Vitamins and Minerals

In addition to the vitamins and minerals such as Vitamin D, C, Zinc, EPA & DHA and Selenium I mention above, there are also others that may help:

Quercetin, a plant flavanol found in many fruits, vegetables, such as red onions and kale, has been shown to have antiviral effects against both RNA (e.g., influenza and coronavirus) and DNA viruses (e.g., herpesvirus) (10).

Curcumin, the active ingredient of the Indian spice Turmeric, Curcumin may target virus replication (11).

EGCG, the active ingredient in Green Tea, has been shown to be effective in the Influenza Virus (12) AND SARS-CoV-2 infections (13).

N-Acetylcysteine (NAC) promotes Glutathione production, which is the main master antioxidant in the body. NAC supplementation has been found to reduce the incidence of Influenza in 262 elderly subjects (14).

Resveratrol, the beneficial ingredient in red wine, which also can be found in large quantities in Japanese Knotweed, has been found to be effective in viral respiratory infections such as MERS-COV infections (15).

Vitamin A, is an important vitamin for immune function and has been shown to be effective in various infectious diseases (16). It is important to note that a large number of people lack the enzyme that converts Beta Carotene (from vegetarian foods such as carrots, oranges etc.) into Retinol, the Vitamin A that our bodies can actually use.

Please note that all advice on herbs and supplements is for general knowledge only and any of these may have interactions with over the counter or prescription medications, so best to work with a specialist such as a Registered Nutritional Therapist.


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  2. Carrelli A, Bucovsky M, Horst R, Cremers S, Zhang C, Bessler M, et al. Vitamin D Storage in Adipose Tissue of Obese and Normal Weight Women. J Bone Miner Res. 2017;
  3. Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, et al. Vitamin D supplementation to prevent acute respiratory tract infections: Systematic review and meta-analysis of individual participant data. BMJ. 2017;
  4. Mirsoian A, Bouchlaka MN, Sckisel GD, Chen M, Pai CCS, Maverakis E, et al. Adiposity induces lethal cytokine storm after systemic administration of stimulatory immunotherapy regimens in aged mice. J Exp Med. 2014;
  5. Wang S, Ma P, Zhang S, Song S, Wang Z, Ma Y, et al. Fasting blood glucose at admission is an independent predictor for 28-day mortality in patients with COVID-19 without previous diagnosis of diabetes: a multi-centre retrospective study. Diabetologia. 2020;
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  13. Ghosh R, Chakraborty A, Biswas A, Chowdhuri S. Evaluation of green tea polyphenols as novel corona virus (SARS CoV-2) main protease (Mpro) inhibitors–an in silico docking and molecular dynamics simulation study. J Biomol Struct Dyn. 2020;
  14. De Flora S, Grassi C, Carati L. Attenuation of influenza-like symptomatology and improvement of cell- mediated immunity with long-term N-acetylcysteine treatment. Eur Respir J. 1997;
  15. Lin SC, Ho CT, Chuo WH, Li S, Wang TT, Lin CC. Effective inhibition of MERS-CoV infection by resveratrol. BMC Infect Dis. 2017;
  16. Huang Z, Liu Y, Qi G, Brand D, Zheng S. Role of Vitamin A in the Immune System. J Clin Med. 2018;