cit-title-group
Abstract
Downloaded from jn.nutritn.org by guest on January 17, 2011 Determining the value of foods as a source of niacin is complicated by dietary trypto phan being a second and variable source of niacin activity depending on the amino acid balance of the whole diet and the hormonal balance of the recipient. A further factor, which is the subject of the present paper, is the indicatn that the availability of the ac tual niacin in varus foods differs widely. It has long been known that a large pro portn of the niacin in cereals remains in chemically bound forms after simple extrac tn procedures at near-neutral pH, and ex periments with rats and some other animal species have indicated that this bound niacin has low or even negligible blogical activity (1, 2). It is the implicatn from a long series of studies by Kodicek and colleagues and by others (3, 4) that measuring just the "free niacin" (i.e., the nicotinic acid and amide) of mild extracts of foods by chromatography would give a better predictn of the blogi cally useful (i.e., available niacin) than do the conventnal analytical methods, which be gin with acid or alkaline digestn so as