Why essential nutrients have never been more … essential

As the world attempts to navigate its way through the havoc wreaked by the COVID-19 pandemic, many lessons will have been learned: some good, some bad, reflects Professor David Richardson, Scientific Adviser, Council for Responsible Nutrition UK

Perhaps not surprisingly, though, supplement suppliers, manufacturers and retailers have all been reporting record growth, with recent Amazon figures revealing that in one particular week in April, 17 of the top 20 vitamin category products sold were immune related.

It’s interesting to note, however, that when it comes to public health discussions about immunity and infection, nutritional strategies to support the optimal function of the immune system are rarely top of the agenda. This is somewhat unexpected, perhaps, given the fact that the important role nutrition plays in immune function is well established.

In light of the pandemic, Public Health England (PHE) recently reiterated its advice on vitamin D for the whole population rather than just vulnerable groups. And it is urging the public to consider taking 10 µg of vitamin D to keep bones and muscles healthy … as they may not be getting enough vitamin D from sunlight if stuck indoors for most of the day during lockdown.

PHE goes on to say that, despite some news reports about vitamin D reducing the risk of coronavirus, there is no evidence to support that. It also stops short of making a direct link between vitamin D and its effect on the immune system.

And whereas the UK NHS acknowledges emerging reports of vitamin D reducing the risk of coronavirus, it also says that, currently, there is no evidence that this is the case.

Despite this, a new study claims that those with vitamin D deficiency could be more likely to die from coronavirus. In the study, which has not yet been peer-reviewed, scientists from Queen Elizabeth Hospital Foundation Trust and the University of East Anglia, write: “We believe that we can advise vitamin D supplementation to protect against SARS-CoV-2 infection.”

The paper also states that vitamin D levels are found to be severely low in the ageing population, especially in Spain, Italy and Switzerland.

"These are countries with high number of cases of COVID-19 and ageing people are in the group with the highest risk for morbidity and mortality with SARS-Cov-2,” say the authors. Such findings will come as no surprise to Professor David Richardson, Scientific Adviser at the Council for Responsible Nutrition UK (CRN UK).

“In the elderly population, age-related immunological changes may create a double burden of chronic and infectious diseases such as flu and coronavirus,” he says.

“Micronutrients play a key role in the immune system and the highly complex defence mechanisms in the body are designed to help protect people of all ages against a host of infectious agents, including bacteria and viruses. Poor nutritional status is associated with impaired immune function in people of all ages, but particularly those older than 60 years of age, so improved nutrition and micronutrient supplementation can help to enhance immune responses.”

“Suboptimal intakes of essential nutrients and micronutrient status are not only evident in the general population, but also in various care settings and for elderly people in the community,” he adds. COVID-19 and influenza affect the respiratory tract by direct viral infection and/or damage to the immune system response. The most vulnerable people are patients in hospital or residents in nursing or care homes.

Only a few foods such as oily fish, cod liver oil, eggs, dairy products and fortified fat spreads contain vitamin D. And, according to Professor Richardson, in the UK there is a very high prevalence of vitamin D deficiency and suboptimal intakes not only in older people and critically ill patients, but also in the general population.

Most of vitamin D3 is formed in the skin when it is exposed to sunlight. For people who are unable to go out into the sunshine, are self-isolating or social distancing because of COVID-19 measures, their vitamin D levels (blood 25[OH]D) are likely to be low.

New research

A recent paper by Grant, et al., summarised the clinical and epidemiological discoveries relating to COVID-19, and the possible roles of vitamin D in reducing the risk of disease.1

The authors observed that people with chronic diseases have lower blood 25(OH)D concentrations compared with healthy people. This is the nutritional biomarker for assessing the nutrient intakes and vitamin D nutritional status of individuals — and low concentrations adversely affect the immune system.

Furthermore, a DSM expert panel also recently produced a paper on immunity. And the panel, comprising Philip Calder, Anitra Carr, Adrian Gombart and Manfred Eggersdorfer, concluded that supplementation with vitamins A, B6, B12, C, D, E and folate, trace elements including zinc, iron, selenium, magnesium and copper, and the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid, is a safe, effective and low-cost strategy to help support optimal immune function.

The experts went on to recommend supplementation above the recommended dietary allowance (RDA) levels for vitamins C and D.

Their conclusions were based on recent meta-analyses that showed significant reductions in the risk and impact of both upper and lower respiratory tract infections with vitamin C supplementation, and the reduced risk of respiratory tract infections in both children and adults with daily or weekly vitamin D supplementation.2

The paper appears to confirm the findings of an earlier study that looked at the role of vitamin D supplementation in the prevention of acute respiratory tract infections.3 The systematic review and meta-analysis of individual participant data reported a major indication for vitamin D supplementation in the prevention of acute respiratory tract infection.

The authors concluded: “Vitamin D supplementation is safe and protects against acute respiratory tract infection overall. Our results add to the body of evidence supporting the introduction of public health measures such as food fortification to improve vitamin D status, particularly in settings where profound vitamin D deficiency is common.”

Now and the Future

“No one knows how long the public health and safety measures will be needed to reduce exposure to the virus and to slow the spread of this disease,” adds Professor Richardson.

“However, healthy eating and maintaining and improving nutritional status are vital to keep your body in top condition — both physically and mentally. But in such unprecedented times, eating a varied and balanced diet can be a challenge, particularly when it comes to key micronutrients that support the immune system, including vitamins A and D, B vitamins and the essential minerals and trace elements iron, copper, zinc and selenium.”

He says that for those who are self-isolating or unable to go outside into the sunshine, a daily supplement of at least 10 µg/day of vitamin D will help to ensure healthy vitamin D status. “Food supplements are part of the strategic dietary advice for vulnerable groups such as the elderly, women at various life stages, children and adolescents … and those people who are watching their weight or have lost their appetite.”

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“Lifestyle factors such as daily exposure to sun, outdoor physical activity and the amount of body surface exposed contribute to optimal vitamin D status. Also, the winter sun in the UK does not contain sufficient of the necessary wavelength UV light to enable human skin to produce useful levels of Vitamin D."

"Even in summer, any restrictions on outdoor activities could result in less sun exposure. Surveys of nutrient intake and nutritional status in the UK demonstrate chronic shortages of several micronutrients, and not only suboptimal intakes of vitamin D,” he added.

And although messages about the importance of a balanced diet and a healthy active lifestyle should always underpin nutrition advice to the public, Professor Richardson concludes: “There is now, more than ever, a need to give evidence-based scientific advice about the role of food supplements as sources of essential nutrients.”


  1. www.ncbi.nlm.nih.gov/pubmed/32252338.
  2. www.preprints.org/manuscript/202003.0199/v1.
  3. www.bmj.com/content/356/bmj.i6583.