Martin Kohlmeier, MD, PhD
Review by Shane McAuliffe RD and Prof Sumantra (Shumone) Ray on behalf of the NNEdPro Nutrition & Covid-19 Taskforce
I am just reading that the Director-General of the World Health Association, Tedros Adhanom Ghebreyesus told a briefing that the Covid-19 pandemic ‘is not even close to being over’. We need to aggressively explore all opportunities to control the continued spread of this very dangerous virus. In addition to the various proven infection control measures, dietary and lifestyle factors affecting large numbers of our populations also appear to be of importance. And in light of the continuing infections, I, like many health professionals also wanted to know how to ensure optimal nutrition as a foundation for successful treatment outcomes.
Several recent reports in BMJ Nutrition, Prevention & Health are now addressing the role of immunonutrition in the spread of SARS-CoV-2, the development of Covid-19, and the role of nutrition in the care of affected patients (https://nutrition.bmj.com/content/early/recent). A seminal review examines in detail the mechanisms whereby specific nutrients maintain well-balanced immune function. A lack of critical factors can leave the immune system too weak to fend off infections at the earliest stage when the body has not formed antibodies, yet. An excess of some nutrients, such as omega-6 fats, may increase vulnerability to excessive activation of the immune system and result in an often deadly cytokine storm.
Several other articles highlight how poor nutrition can contribute to the spread of the virus and unfavourable outcomes. Metabolic health is important as well as the right amounts of macro- and micronutrients. Individuals with diabetes, obesity and high blood pressure, all conditions with strong nutritional components, have a greatly increased risk to become severely ill and often even die when they get infected. Older people in particular, who more often than others succumb to Covid-19, commonly do not get enough of important nutrients such as protein, zinc, vitamin A, vitamin C, and vitamin D, as reported in several more contributions. A case study of a Covid-19 patient reports that, despite being originally healthy and under forty years old, the developing malnutrition became a challenge that had to be overcome for his ultimately successful treatment.
A number of scientists favor the hypothesis that vitamin D deficiency is the seasonal factor that provides an opening for infections with many respiratory viruses including SARS-CoV-2. Diverse observations around the globe appear to align with this hypothesis. The contributions in BMJ Nutrition, Prevention & Health consistently emphasize that moderately dosed vitamin D supplements within current guidelines are usually sufficient to prevent severe vitamin D deficiency and that very high doses in excess of 4000 IU should be avoided outside clinical treatment under medical supervision. These messages have recently been echoed in guidelines from national agencies.
Unfortunately, there is still a lot of resistance to the concept that severe vitamin D deficiency may contribute to the current pandemic. While health claims should ideally be supported by the highest scientific standards and we usually wait patiently until we can be reasonably sure, in cases like this acute pandemic we have to settle for what little we know because the virus will not sit still for us to settle on unanimous agreements based on consistently replicated gold standard studies. The currently available evidence is already leaning towards the view that prevention of severe vitamin D deficiency slows SARS-CoV-2 transmission, even if the final verdict is still pending.
Preventing severe vitamin D deficiency with moderately dosed dietary supplements in line with current guidelines is already official policy, just not for the purpose of Covid-19 prevention. After half a year of so many errors of judgment that have fed this pandemic, we cannot afford to be yet wrong again for the sake of misguided striving for perfection.
We need to take seasonal vitamin D deficiency deadly serious and act now to eradicate this recurrent health threat.
Martin Kohlmeier, MD, PhD
Professor and Director, Human Research Core and Nutrigenetics Laboratory
Director, Nutrition in Medicine (NIM)
UNC Nutrition Research Institute, and School of Medicine & Gillings School of Global Public Health, University of North Carolina at Chapel Hill
Editor in Chief, BMJ Nutrition, Prevention & Health
NNEdPro GIP Principal Advisor