| Summary: | Two studies were conducted to determine the effect of varying vitamin B-6 (B-
6) status on lymphocyte mitogenic response and pyridoxal 5'-phosphate (PLP)
concentration in peripheral blood mononuclear cells (PBMC) in young women. In the
first study, women were fed 1 mg/d for the first week and 1.5, 2.1 and 2.7 mg/d during
2 weeks of each of the subsequent 3 experimental periods. Plasma PLP and urinary 4:
pyridoxic acid (4-PA) were increased with increasing B-6 intake. B-6 intake > 2.1 mg
significantly enhanced lymphocyte proliferation, and non-significantly increased
plasma interleukin-2 concentration. Lymphocyte proliferation was significantly
correlated with B-6 intake, erythrocyte aminotransferase activity coefficients and
plasma PLP. PBMC PLP tended to increase after 2 weeks of 2.7 mg B-6 intake, and
was significantly correlated with plasma PLP. In the second study, women consumed
their normal diets whose estimated mean dietary B-6 intake was 0.9 mg for 27 d. For
the last 20 d, all subjects were given a multivitamin supplement containing 1.8 mg B-
6, and half of the subjects were given an additional 50 mg of B-6 supplement. Plasma
PLP and urinary 4-PA were significantly higher in the group with 50 mg B-6, but
lymphocyte proliferation did not significantly differ between the groups. After 10 d of
supplementation, lymphocyte proliferation was significantly higher than the other time
points. A significant increase in PBMC PLP was observed after 3 days and 20 days
following 50 mg and multivitamin supplementation only, respectively. After 20 days
of supplementation, there was no significant difference of mean PBMC PLP between
the groups. PBMC PLP was significantly correlated with plasma PLP, PL and 4-PA.
In both studies, no strong relationship was found between PBMC PLP and lymphocyte
proliferation. The findings from these studies demonstrate no further benefit of a
higher B-6 intake than 2.1 mg on lymphocyte mitogenic response, once the response
was significantly enhanced with B-6 intake 0.8 mg higher than the current
recommendation. Finally, results from two studies suggest that the current
recommendation of vitamin B-6 for young women may not be adequate to maximize
lymphocyte mitogenic response and PLP concentration in PBMC. === Graduation date: 2002
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