Link Between Immunity and Vitamin D3

The skin plays a major role in immune function. Exposure to the sun generates vitamin D3, which regulates immunity. It boosts immunity if it is deficient and suppresses immunity if it is overactive.

Vitamin D3 (not just vitamin D) also stimulates the body to produce protective chemicals called antimicrobial peptides, which protect against autoimmune diseases. This explains why multiple sclerosis is more common in the northern latitudes, where the sunshine is less intense and prolonged.

The same is true for flu complications and other communicable infections. Children with higher vitamin D3 intakes have far fewer infections and recover faster when they are infected. Vitamin D3 stimulates production of infection-killing chemicals called antimicrobial peptides. Interestingly, exposure to excessive UV light (sunlight) also can suppress immunity in the skin and even overall immunity. This is a common symptom with sunburns.