Thioctic Acid in Complete and Deficient Diets for Chicks

THIOCTIC acid (6,8-dithiooctanoic acid, lipoic acid, protogen) is known to be an important growth factor for protozoa and bacteria, as well as a component of certain enzyme systems in microorganisms and animal tissues (see reviews by Gunsalus, 1954; and Reed and DeBusk, 1954). Despite little evidence for its growth promoting activity in higher animals, thioctic acid has been called a vitamin (Seaman, 1952; Anonymous, 1953; Fischer, 1955) and has been included as a B vitamin in recent reviews on the vitamin B complex (Cheldelin, 1954; Johnson, 1955; Plaut and Betheil, 1956). DeBusk and Williams (1955) reported that thioctic acid added to a purified diet stimulated the growth of White Leghorn chicks and of Wistar rats. However, Stokstad, Broquist and Patterson (1953) had reported earlier that they could not produce a growth response with thioctic acid in chicks or rats fed a purified diet. Recently, Stokstad et al. (1956) and workers . . .