Let's talk about Vitamin D. Hundred's of scientific studies have shown us that every cell in the body has a Vitamin D receptor, including activated immune cells. Vitamin D not only regulates calcium transport for our bones, but 80 different metabolic pathways are influenced by Vitamin D, including DNA repair.
We get very little Vitamin D from food (oily fish, mushrooms and fortified milk) and the majority of it comes from the sun. From November - March, if you live at latitudes above Atlanta, Georgia, you won't get any Vitamin D from your skin. Even at the Equator, you will absorb no sun Vitamin D before 9am or after 3:00 pm. Vitamin D deficiency is a worldwide problem as there are a number of metabolic steps in our bodies that are necessary to convert sunlight into the 24 OHD Vitamin D that our body uses.
Viral colds, flu and influenza infections peak between January and March just as seasonal low Vitamin D levels are also seen in those months. Studies have shown that when blood levels are above 30 ng/ml there is a 45% decrease in upper respiratory infections and above 38 ng/ml there is a 2 fold decrease in infections. Blood Vitamin D levels are optimal at about 55 ng/ml.
Now we know that Vitamin D also affects Covid risk and severity. Low Vitamin D is an independent risk factor for Covid infection.
A recent study of 191K patients showed a linear decreased risk of Covid-19 infection when blood levels of vitamin D climbed to 55 ng/ml. There was no difference in race, age, high latitudes, or sex. In all groups lower levels had more infection and worsening infection and death. The Covid-19 virus attaches to the ACE2 receptor and that receptor also responds to Vitamin D, along with immune cells that ward off cytosine storm.
Everyone should be supplementing with inexpensive Vitamin D. Yes, it is toxic at very high doses but it is difficult to become toxic with small replacements of Vitamin D. I will recommend a minimum of 2000 IU/day for my patients and most should take 4000-5000 a day to maximize blood levels to 50ng/ml.
Another benefit: Adequate Vitamin D blood levels may also affect the ability to tolerate statin medication (used for high cholesterol/lipids). One study showed subjects who had a Vitamin D level under 32 and were unable to tolerate statins were replaced with 50,000 IU weekly for two years. When re-challenged with a statin, 88-95% of them could tolerate the statin with Vitamin D levels raised to 53-55 ng/ml