Other food factors Para-aminobenzoic acid
Para-aminobenzoic acid (PABA) is a moiety of pteroylmonoglutamic acid (PGA), one of the forms of folic acid, and is no longer considered a vitamin.
Inositol
Inositol was first considered to be a vitamin in 1940, but there is no evidence today that humans cannot synthesize all that is needed by the body.
Choline
The classification of this nitrogenous compound as a vitamin is questioned by some. It is a structural component of body cells rather than a catalyst. It also is a precursor ofthe neurotransmitter, acetylcholine. Choline occurs in foods as well as in the body in relatively large amounts and has never been associated with a deficiency disease in humans. The body can make choline from methionine, an amino acid, with the aid of vitamin B12 and folacin. The action of choline, betaine or methionine in the prevention of so-called fatty livers is known as lipotropic (fat moving); all three compounds serve as methyl-group donors in the body. Choline is distributed widely in plant and animal tissues, and a deficiency is not likely in the average diet.
Carnitine
Carnitine is another nitrogenous compound found in tissues and foods which, like choline, has a definite biologic function in the body. Carnitine appears to accept the acyl-groups oflong chain fatty acids from acyl CoA and (as acyl carnitine) translocates them through the mitochondrial membranes to the matrix where they can be oxidized. Carnitine is not considered a vitamin, because it
can be synthesized in the body and therefore no dietary requirement for it exists. The possible role of carnitine in various disorders of lipid metabolism is under investigation.
Biofl avonoids
Bioflavonoids are a group of widely distributed phenolic compounds that exhibit some biologic activity in higher animals. They appear to have both antioxidant and metal-chelating properties. However, there is no evidence that they have any biologic function in the body and have not been shown to be required by any species. Therefore, they are not vitamins despite being designated as vitamin P in the older literature.
