Given how much I love the sun, you shouldn’t be surprised to learn that vitamin D is one of my favorite nutrients. We make vitamin D in the skin in response to sun exposure through a kind of a mammalian version of photosynthesis. The newly minted vitamin then regulates the expression of DNA in hundreds of physiologic reactions. I have a great post on sun exposure here on my blog: https://www.drericaoberg.com/post/skin-sunscreen-and-science.
Unfortunately, modern life has us avoiding the sun to prevent potential illness and slow aging. The combination of clothing and sunscreen has changed our intake and Vitamin D deficiency is now fairly common. This deficiency has been linked to conditions such as colorectal and breast cancer, osteoporosis and rickets, eczema, and of course, immune function. A recent Medscape publication featured research from Ireland linking Vitamin D deficiency with higher rates of Covid-19 mortality. Significant, because Ireland is a cloudy, grey place with a high rate of vitamin D deficiency[1]. In a nice example of applying scientific data to public health policy, scientists are calling on the government to update guidelines and recommendations to encourage all adults to take vitamin D supplements during the Covid-19 crisis.
Vitamin D is a potent immune system modulator. There are vitamin D receptors (VDR) on every type of immune cell and adequate levels are needed to keep the cells functioning. Importantly, it regulates both sides of the immune system, ensuring your “battalion” cells, like macrophages, are ready to fight off a virus or bacteria and your innate immune system is making appropriate antibodies to protect against future exposures[2].
Finally, if you crave more knowledge about this extremely interesting and useful Vitamin, here’s a nice document summarizing the power of vitamin D, published by the Linus Pauling Institute, one of my go-to resources for accurate, research-cited nutrient information – enjoy! https://lpi.oregonstate.edu/mic/vitamins/vitamin-D