In recent weeks and months, there’s been an upshot of studies(1) demonstrating the benefits of vitamin D against COVID-19. More than 200 doctors, scientists, and leading authorities have signed an open letter(2) calling for increased use of vitamin D in the fight against COVID-19. “Research shows low vitamin D levels almost certainly promote COVID-19 infections, hospitalizations, and deaths. Given its safety, we call for immediate widespread increased vitamin D intakes,” the letter states. “Vitamin D modulates thousands of genes and many aspects of immune function, both innate and adaptive,” it continues before listing some of the validated findings on vitamin D. The authors note that higher vitamin D blood levels are associated with lower rates of SARS-CoV-2 infection and a lower risk of a severe case (hospitalization, ICU, or death). Vitamin D’s effectiveness is also shown in intervention studies, they say, adding that many research papers reveal several biological mechanisms …