VITAMIN-B-6 STATUS INDICATORS DECREASE IN WOMEN CONSUMING A DIET HIGHIN PYRIDOXINE GLUCOSIDE

Previous research has shown that the pyridoxine glucoside (PNG) form o f vitamin B-6 has a reduced bioavailability compared with pyridoxine, but its effect on vitamin B-6 status has not been assessed. Following an 8-d adjustment period, nine women consumed diets containing a high or low amount of PNG for 18 d each, in a crossover design, The high an d low PNG diets provided 1.52 mg/d (8.98 mu mol/d) and 1.44 mg/d (8.57 mu mol/d) of vitamin B-6, of which 27% and 9% was PNG, respectively. The dietary vitamin B-6 to protein ratio of both diets was 0.017 mg/g. Urinary excretions of 4-pyridoxic acid and total vitamin B-6 were sig nificantly lower (P < 0.05) during the high PNG diet period than when the low PNG diet was consumed. Urinary PNG excretion was equal to abou t 9% of the total PNG intake during both periods. Plasma total vitamin B-6 (P < 0.01) and red blood cell pyridoxal 5'-phosphate (PLP) (P < 0 .05) were significantly lower when the high PNG diet was consumed than during the low PNG diet period. Fecal total vitamin B-6 excretion was significantly higher (P < 0.001) when the high PNG diet was consumed. Women consuming a diet containing a higher percentage of the total vi tamin B-6 intake as PNG exhibited a decrease in vitamin B-6 status ind icators, consistent with the reduced bioavailability of PNG demonstrat ed in other studies, equal to a loss of 15-18% of the total vitamin B- 6 intake. During the determination of Recommended Dietary Allowances, the reduced bioavailability of PNG and its presence in higher amounts in some diets should be considered.