Foods, which are rich in
niacin, are cereals and cereal products (e.g., bread), yeast and yeast products, meat and fish. A
deficiency in niacin results in pellagra, which is a nutritional disease endemic among communities
who subsist chiefly on maize (Ball, 1994). The vitamin occurs naturally both in the free and bound
forms (e.g., nicotinic acid and nicotinamide). It is generally considered that only the acidhydrolysable
forms are fully bioavailable for humans; thus if the nutritive value is to be
determined, an acid hydrolysis is preferable. However, if the total niacin activity is to be
determined, an alkaline procedure should be chosen. Various methods have been used to
determine natural levels of niacin in food. These include the traditional colorimetric procedure
using cyanogen bromide and sulphanilic acid, the microbiological assay using Lactobacillus
plantarum and various chromatographic methods (Ball, 1994). The colorimetric method, although
robust, requires the use of cyanogen bromide which is toxic and is no longer available on the
international market. The microbiological assay is less robust, has a narrow range of
determination; it is also difficult to obtain consistent results