My favorite blogs are those prompted by questions from the Zing audience. This week I received one about the role of Vitamin D in supporting the immune system.
Vitamin D: the Basics
Vitamin D is a fat soluble vitamin that plays a critical role in our ability to absorb calcium. It is called the “sunshine vitamin” because it produced in the body when sunlight strikes the skin and activates Vitamin D synthesis. It doesn’t take a lot of sunlight. Being outside three times a week for 10 minutes a day with at least a third of the body exposed is sufficient. It is harder to get the recommend 600-800 IU of Vitamin D per day just from food. Most foods don’t contain it, with exceptions like salmon, Vitamin-D fortified cereals and drinks, and mushrooms exposed to UV light.
Vitamin D and Immune Health
In the last decade, researchers have studied the link between Vitamin D and the immune system. It appears Vitamin D plays a role in keeping both the innate and adaptive immune system strong (1). The innate immune system is our first line of defense against pathogens, and adaptive immunity is what fights specific pathogens we acquire, such as a flu bug. Vitamin D may even play a role in immune tolerance which prevents the over-reaction of the immune system (e.g., allergies).
It’s important to note, however, that the studies done on Vitamin D and immune health are largely observational and don’t prove cause and effect.
Vitamin D and COVID-19
Research in the last five months has looked at the potential role of Vitamin D in reducing the risk of COVID-19 infections and death. This theory was even considered during the 1918 Spanish Flu pandemic when the combination of sunlight and fresh air seemed to improve patients health.
How Much Vitamin D is Enough?
Because Vitamin D is synthesized mostly from sunlight, it is harder to get enough when sheltering-in-place or in winter months. This is especially true for those in the U.S. living above the 37th parallel in cities like San Francisco, Seattle, Chicago and New York.
The Top Takeaway
Vitamin D plays a critical role in bone health, and appears to play an increasingly important role in immune system health. If you have concerns about getting enough Vitamin D from sunlight, talk to your doctor about supplements or a simple blood test to determine Vitamin D levels in your body.