Abstract
The bioavailability of niacin in instant coffee was investigated by using weaning rats fed with a niacin-free and tryptophan-limited diet. The growth rate was significantly improved by supplementing instant coffee powder to the niacin-free and tryptophan-limited diet, and the niacin coenzyme levels, NAD and NADP, in the blood and liver were significantly increased. The urinary excretion of nicotinamide and its catabolic metabolites, N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, and N1-methyl-4-pyridone-3-carboxamide, were significantly increased by the addition of instant coffee powder. These results suggest that instant coffee contains very useful precursors of pyridine nucleotide coenzymes to mammals.
