A new study published in the journal Scientific Reportsfrom the group nature, found that supplementing the diet with vitamin D acted as a preventative and mitigating factor for those who caught Covid. Those who took the vitamin had a 20 to 28% reduction in the risk of becoming infected. Among those who became infected, the risk of death in the following month was reduced by 33% if the supplement was in the D3 version (from animal origin) instead of D2 (from plants). Two months of prior supplementation, however, are required for levels in the body to rise. According to the researchers, if vitamin D had been recommended for the entire American population in 2020, 116,000 deaths would have been prevented in the United States.
The study took methodological precautions so that the effects of vitamin D were not confused with natural immunity due to previous infection and other cautious behaviors, such as the use of masks. The data source was a database of US military veterans: 220,000 took vitamin D3, 35,000 took D2, and 408,000 had no supplementation — they were the control group, for comparison.
The authors, led by Robert D. Gibbons, from the Department of Medicine at the University of Chicago, comment that their results corroborate a previous study from Andalusia, in southern Spain, which also observed a 33% reduction in mortality from Covid-19 with vitamin D supplementation. In the case of Spaniards, supplementation was prescribed 15 days before hospitalization and consisted of calcifediol instead of D3.
Vitamin D and skin color
The vitamin occurs in low amounts in food. Therefore, contact with sunlight is important for the production of more D3, from a cholesterol derivative in the skin. It is the beneficial role of ultraviolet rays. Three centuries ago, rickets was described, a bone problem that occurs due to vitamin deficiency. Psychological effects of the molecule deficiency, such as depression, are also known.
Sunbathing is so important that it explains the appearance of fair skin in humans. Originally with dark skin, when occupying regions closer to the North Pole, humans suffered from a lack of vitamin D, in the face of a lower incidence of sunlight. Among the offspring, therefore, children with lighter skin (which block UV rays less) naturally produced more vitamin D and were healthier, having more chances of surviving in the region and leaving offspring. With the passing of generations and the repetition of this process, white skin appeared at least twice in humans: in Europe and in northern Asia. In low latitudes, close to the equator, it is the opposite: the incidence of UV rays is high, and lighter people do not have an advantage, as they have an increased risk of skin cancer, caused by the same sun rays.
Because darker skins have a harder time producing vitamin D naturally, predictably, the study of American veterans found that blacks benefited even more from vitamin D supplementation than whites. The reduction in the risk of infection in blacks was 29%, while in whites it was 18%. Higher blood levels of the vitamin were also associated with greater risk reductions. Among patients who had low levels of vitamin D and were prescribed a supplement with a maximum daily dose of 50,000 IU [unidades internacionais]the reduction in the risks of catching Covid was the largest recorded by the study: 49%.
The authors suggest that their results be tested by studies in which people are randomly assigned to each treatment or non-treatment group, which would add rigor. “Physicians could consider regularly prescribing vitamin D3 to patients with deficient levels to protect against Covid-19 infection and related mortality,” they comment in the article. “A dose of 50,000 IU” daily, they conclude, “may be especially beneficial”.