Vitamin D is a fat-soluble nutrient most classically known for its role in helping the body absorb calcium and promoting bone health. It can also modulate innate and adaptive immune responses. Vitamin D receptors are found on immune cells (B cells, T cells, and antigen-presenting cells) facilitating Vitamin D’s ability to strengthen our natural defense responses. Deficiency in Vitamin D is associated with increased autoimmunity and susceptibility to infection. Research suggests that Vitamin D may improve respiratory function.*