Amid the excitement of vaccine approvals and roll outs, you can’t have missed the news that vitamin D might help to reduce COVID severity, and might even prevent it. My own husband is of Greek heritage and, living in the UK where we have been hard hit by the virus, he was absurdly proud of his countrymen in Greece who – initially at least – weathered the storm with remarkably low mortality rates.
“It’s the Greek weather,“ he assured me (when he wasn’t busy assuring me that “It’s the diet”).
Sure enough, by mid-2020, researchers were drawing significant correlations between lower death rates and a country's proximity to the equator; reduced mortality was attributed, at least to a certain extent, to sunlight UV radiation exposure on the skin and the production of vitamin D. This type of research was consistent with numerous other studies demonstrating correlations between mean vitamin D levels and COVID mortality.
Current theories on the mechanisms at play include the immunomodulatory role of vitamin D, which increases immunity via the secretion of antiviral peptides and the improvement of mucosal defences. Additionally, a role in suppressing cytokine production means that it may have some effect on the ‘cytokine storm’ famously associated with severe COVID.
Vitamin D supplementation has been deliberated since the 1920s, when it was found to prevent rickets. The vitamin plays various roles in the human body, including bone growth and maintenance, immune function and cardiovascular health. Data from observational studies also suggest that it may reduce respiratory infections, though results have been inconsistent. Therefore, vitamin D supplementation, its potential benefits and uses, have been debated for around 100 years. It seems that, as with many things that have been accelerated or heightened by the pandemic, COVID is now escalating that discussion too.
Experts have cautioned that many of the studies linking vitamin D deficiency to COVID severity have been observational or retrospective, and that a relationship is yet to be conclusively proven. Randomized control trials and cohort studies are required. Nevertheless, if a link between Vitamin D and COVID severity were to be proven, surely that would offer a relatively simple approach to helping us cope with the ongoing pandemic.
Even before the pandemic, government guidelines in the UK, US and across the EU advised supplementation with vitamin D. Many people have low blood levels of the nutrient, especially in winter, because summer sunshine is usually the main source of vitamin D for a temperate country’s population. It is very difficult to achieve adequate levels through diet alone. Therefore, government recommendations are to take supplements of 10 µg/day in the UK, and 15 µg/day In the USA and the EU. However, most people simply don’t bother (or are unaware of the guidance).
Some scientists in the UK, presumably convinced of the link between vitamin D and COVID, are now calling for ministers to add vitamin D to common foods such as bread to help the fight against the virus. Systematic food fortification is seen as a cost-effective approach that, when used in foods eaten by the overwhelming majority of a population, will ensure compliance with a government-recommended supplementation strategy.
Analysts have acknowledged that the COVID pandemic has accelerated global vitamin D market growth, thanks to a rising number of government initiatives and awareness campaigns. According to MarketsandMarkets, the vitamin D market was worth $1.1 billion in 2020 and is projected to reach $1.6 billion by 2025, at an annual growth rate of 8.4%. The synthesis of vitamin D is a multi-stage process, beginning with 7-dehydrocholesterol. Companies along the supply chain may be wise to look out for new growth opportunities as more data from ongoing COVID trials are revealed, and their impacts on public health campaigns are felt.
Of course, until the results of prospective studies are available, it is impossible to say whether calls for food fortification in temperate countries, or novel proposals for vitamin D supplementation in countries that have not historically advised it, would truly have a direct effect on COVID prevalence and/or severity. However, for countries in which whole populations are already advised by public health authorities to take vitamin D supplements in winter months, for general health purposes, it is difficult to understand why anyone would object to the proposal.
Vitamin D supplementation is a low-risk intervention that is unlikely to do harm, but will almost certainly do some good to a lot of people. If it also turns out to also help manage the severity of the COVID pandemic, then surely that’s a bonus!
Sarah Harding, PhD
Editorial Director of Chemicals Knowledge
Sarah Harding worked as a medical writer and consultant in the pharmaceutical industry for 15 years, for the last 10 years of which she owned and ran her own medical communications agency that provided a range of services to blue-chip Pharma companies. She subsequently began a new career in publishing as Editor of Speciality Chemicals Magazine, and then Editorial Director at Chemicals Knowledge. She now focusses on providing independent writing and consultancy services to the pharmaceutical and speciality chemicals industry.