VITAMIN-B-6 REQUIREMENT AND STATUS ASSESSMENT OF YOUNG-WOMEN FED A HIGH-PROTEIN DIET WITH VARIOUS LEVELS OF VITAMIN-B-6

The vitamin B-6 requirement of young women consuming a constant high-p rotein diet (1.55 g/kg body wt) and the effect of various ratios of vi tamin B-6 to protein on this requirement were studied. Eight women wer e fed a lactoovovegetarian basal diet containing 0.45 mg vitamin B-6 ( 2.66 mu mol as pyridoxine) and 30 mu mol carnitine for 92 d. The proto col consisted of successive baseline adjustment (9 d), depletion (27 d ), and repletion (two 21-d and then one 14-d) periods. Vitamin B-6 int akes were 1.60, 0.45, 1.26, 1.66, and 2.06 mg, resulting in ratios of vitamin B-6 (in mg) to protein (in g) for the five periods of 0.016, 0 .005, 0.013, 0.017, and 0.021,respectively. Direct and indirect as wel l as short-and long-term vitamin B-6 status measures were assessed wee kly. Regression analysis revealed that the amount of dietary vitamin B -6 required to normalize urinary 4-pyridoxic acid, plasma pyridoxal-P, erythrocyte pyridoxal-P and pyridoxal, and erythrocyte alanine and as partate aminotransferase activity coefficients to predepletion baselin e values was 1.94 mg vitamin B-6/d (0.019 mg vitamin B-6/g protein). T his study suggests that the current vitamin B-6 recommended dietary al lowance of 1.6 mg/d based on 0.016 mg/g protein is not an adequate int ake and may require reevaluation.