A cofactor is a chemical compound that is required for certain enzymes — called conjugated enzymes — to become active. Vitamins and minerals serve as the cofactors required by the human body to function properly. These nutrients may either be cofactors themselves or may be chemically modified to become cofactors once they are in the body.
Vitamins are organic substances that are not produced by the body, but are required in order for it to function. Many, but not all, vitamins become cofactors in the body. Coenzyme is another term often used to describe vitamins that function as cofactors. Most vitamins are converted into cofactors once they are in the body; only vitamin C is used directly as a cofactor.
Both fat-soluble and water-soluble vitamins function as cofactors. Vitamins A, D, E, and K are fat-soluble; however, only K is used as a cofactor. The remaining vitamins — all the B vitamins, vitamin C, niacin, biotin, folic acid, panthothenic acid, and lipoic acid — are water-soluble, and all are converted into cofactors once in the body — with the exception of vitamin C, which is utilized directly.
Most minerals required by the human body also function as cofactors. Potassium, chloride, sodium, calcium, phosphorous, and magnesium are the major minerals required by the body. Iron, zinc, manganese, iodine, copper, selenium, and molybdenum are also required in trace amounts.
Deficiency in any one vitamin or mineral cofactor can lead to a number of medical conditions. In fact, enzyme cofactors were first discovered because of one such disease: beriberi. This condition — a deficiency in vitamin B1, or thiamine — was due to diets composed mainly of white rice. It is less common in modern times than when it was first diagnosed in the early 1900s.
Anemia, which is a deficiency in iron, is one of the more commonly found deficiencies. It may be caused either by not getting enough iron in one's diet or by an inability of the body to properly absorb iron. While red meat is commonly thought to be the main source of iron in a diet, leafy vegetables and beans are also good sources.
Vitamin B12 is another common deficiency and is of particular concern for vegetarians and vegans. Vegetarians who consume enough eggs and dairy products generally receive enough B12, unless their bodies have difficulty absorbing vitamin B12. Vegans may find it necessary, however, to take a vitamin B12 supplement or eat fortified foods, as B12 is mainly found in animal products.