We all know two things for sure: (1) Sunlight makes our body product Vitamin D; and (2) too much sunlight is bad for us and might cause cancer. Haven’t we all heard that many times? But wait! Recent evidence suggests that sunlight may improve immune by boosting infection–fighting immune cells and discouraging the spread of pathogens in hospitals. A 2018 study, revised July 2020, indicates that sunlight exposure may have immunomodulatory effects and protect against infections, including acute respiratory infections such as influenza. It’s a long article, but well worth the read. You can download or just read a pdf format of the article at https://www.nber.org/papers/w24340.
In addition, believe it or not, studies have shown that high levels of solar ultraviolet radiation (UVR) exposures are associated with lowered rates of allergies, autoimmune diseases, and cancers. While often acknowledged that these results are from increased vitamin D, researchers find that exposure to sunlight improves the motility of killer T-cells. They have also found that infectious outbreaks, including influenza, tend to happen more during wintertime, when people have little or no sunlight and UVR exposure.
A 2017 study from Columbia University suggests that UV light can kill even drug-resistant bacteria without causing the dreaded skin damage (https://doi.org/10.1667/RR0010CC.1).
Sunlight exposure has long been known to increase the body’s vitamin D levels. Skin cells absorb UVB radiation and convert it to vitamin D, which is metabolized in your liver and kidneys and used throughout your body to regulate calcium, increase beta-endorphins, and stimulate the immune system. Instead of taking a capsule of 5,000 I.U. or more of D3, we can just make our own!
High levels of vitamin D also improve inflammatory response, lower blood pressure, increase cognitive function, and lower the risk for certain cancers. How long to stay in the sun to do some good? It depends on time of year and location. To calculate your effective time in the sun, go to this Website: https://fastrt.nilu.no/VitD-ez_quartMEDandMED_v2.html