B-group vitamins are required in amino acid catabolism, and recent findings suggest that urine 2-oxo acids, catabolites of amino acid, could be functional biomarkers indicating the nutritional status of B-group vitamins. To clarify the relationship between B-group vitamins and urine 2-oxo acids, we investigated the effects of B-group vitamin administration on daily changes in urinary amounts of 2-oxo acids in humans. Twenty-nine young Japanese women collected 24-h urine samples for 8 d, and took B-group vitamins for 7 d beginning on the second day of urine collection. The participants were divided into three groups on the basis of the amounts of total branched-chain 2-oxo acids, 2-oxoglutaric acid, 2-oxoadipic acid, and pyruvic acid excreted in urine. In the upper tertile, but not the middle and lower tertiles, each urine 2-oxo acid decreased from the first day of vitamin administration, and completely decreased to a normal level on the second day of administration. These results indicate that administration of B-group vitamins immediately affects 2-oxo acid metabolism in some young Japanese women. Thus, urinary 2-oxo acids could be useful and functional biomarkers for B-group vitamin status.
Keywords: 2-oxo acids; B-group vitamins; biomarker; intervention study; urine.