Following unverified reports that high doses of vitamin D could reduce the risk of contracting COVID-19 and be used to successfully treat the virus, the new study, published in the journal BMJ, Nutrition, Prevention and Health, investigated the current scientific evidence base on the vitamin and its use in treating infections.
Vitamin D is a hormone, produced in the skin during exposure to sunlight, and helps regulate the amount of calcium and phosphate in the body, which are needed to keep bones, teeth and muscles healthy.
"An adequate level of vitamin D in the body is crucial to our overall health, too little can lead to rickets or the development of osteoporosis but too much can lead to an increase in calcium levels in the blood which could be particularly harmful," said study lead author Sue Lanham-New, Professor at the University of Surrey in the UK.
Examining previous studies in this field scientists found no evidence of a link between high dose supplementation of vitamin D in helping to prevent or successfully treat COVID-19 and cautioned against over-supplementation of the vitamin, without medical supervision, due to health risks.
Scientists said that assertions about the benefit of the vitamin in treating the virus are not currently supported by adequate human studies and are based on findings from studies that did not specifically examine this area.
Claims of a link between vitamin D levels and respiratory tract infections were also examined by scientists.
Previous studies in this area have found that lower vitamin D status is associated with acute respiratory tract infections, however, limitations of the findings of these studies were identified.
Findings from the majority of studies were based on data gathered from population groups in developing countries and cannot be extrapolated to populations from more developed countries due to external factors.
Scientists believe that there is currently no firm link between vitamin D intake and resistance to respiratory tract infections.
"Although there is some evidence that low vitamin D is associated with acute respiratory tract infections, there is currently insufficient evidence for vitamin D as a treatment for COVID-19 and over-supplementing must be avoided as it could be harmful," study researcher Carolyn Greig.