Beyond Bone – The importance of vitamin D for immune function in swine

A properly functioning immune system is critical for animal health and survivability. Successful immunity requires a network of cells and molecules working together against invading foreign antigens, and with exposure to challenges occurring daily, it’s an ongoing process. The host defends the body against such challenges by activating both adaptive and innate systems. The innate immune system is the initial reactive arm and front line of defense against foreign substances. Mucosal surface cells of the skin, intestine and lung are the initial contacts. The purpose of the innate immune response is to induce inflammation after recognition of a foreign substance. The adaptive immune system provides a more specific, highly specialized response that takes time to develop, recruits lymphocytes and creates immunological memory. Vitamin D helps regulate both types of immunity. It appears that vitamin D helps maintain self-tolerance by dampening overly eager adaptive immune responses, while enhancing protective innate immune responses. Piglets are exposed to a variety of challenges at weaning, including change in diet, disease, temperature fluctuations, social interactions and handling. The nutritive and metabolic need for antioxidant vitamins is therefore higher in this phase. Though the benefits of vitamin D in preventing and treating metabolic bone disease are well known in swine, its role in supporting the immune system is becoming better appreciated and will be further outlined here.