Vitamin-like Compounds

There are a variety of organic compounds though cannot be defined as true vitamins, which are related to the function of vitamins. Generally speaking, they can be sufficiently synthesized by humans and are not required in the daily diet. Because of similarities in physiological function or distribution in diet, these substances usually are classified as vitamin-like substances. Besides specific amino acids such as methionine and taurine in feathered animals, other examples of these vitamin-like substances include choline, carnitine, inositol and Coenzyme Q.