Differences in vitamin B6 status indicator responses between young and middle-aged women fed constant diets with two levels of vitamin B6

Abstract

The responses of adult women to two levels of vitamin B6, was conducted with five young and eight middle-aged subjects. A constant diet (2.3-2.4 mg vitamin B6 per day) was fed for four weeks followed by three weeks of the same diet supplemented with 8.0 mg pyridoxine. Plasma pyridoxal 5'-phosphate (PLP), plasma and urinary vitamin B6, and urinary 4-pyridoxic acid (4-PA) were determined. The older women had significantly lower plasma PLP, plasma and urinary vitamin B6 and slightly higher urinary 4-PA values on normal vitamin B6 intakes. With supplementation, only the difference in urinary total vitamin B6 remained significant. Tryptophan load tests revealed no significant between-group differences in xanthurenic acid or kynurenic acid excretion. These results demonstrate an age-related difference in vitamin B6 status indicators in women under controlled dietary intake of vitamin B6.