Vitamin B5 (pantothenic acid) is a water-soluble vitamin which serves a key role in the synthesis of coenzyme A (CoA), a cofactor in many metabolic reactions. It is also plays a role in fatty acid synthesis, as it is a cofactor for the enzyme fatty acid synthase. A deficiency in vitamin B5 leads to a enteritis / diarrhea, adrenal insufficiency, dermatitis, and alopecia.