Vitamin B6 nutritional status of a group of female adolescents

Abstract

The vitamin B6 nutritional status of 127 females between the ages of 12 and 14 years was evaluated by nutrient intakes calculated from 24-hr dietary recalls, by measurement of erythrocyte alanine aminotransferase activity and its stimulation by pyridoxal phosphate in vitro and by vitamin B6 levels in erythrocytes. Approximately one-half of the subjects consumed less than two-thirds of the recommended dietary allowance for vitamin B6; the mean daily intake of the vitamin was 1.24 mg ± 0.70 (SD) or 79% of the recommended dietary allowance for this age group. A high stimulation of erythrocyte alanine aminotransferase ≥16% following the in vitro addition of pyridoxal phosphate was used as an indicator of vitamin B6 inadequacy. Based on this criterion, 31% of the subjects showed some inadequacy of the vitamin. Other investigators have used a more rigorous standard of ≥ 25 % stimulation by pyridoxal phosphate (equivalent to erythrocyte alanine aminotransferase index of 1.25) to indicate inadequacy of vitamin B6. By the use of this criterion 13% of the subjects were judged to be in poor status. The vitamin B6 nutritional status of 32 subjects evaluated in the spring and reevaluated in the fall followed a pattern consistent with their changes in vitamin B6 intake. Vitamin B6 levels in erythrocytes did not appear to be a sensitive indicator of vitamin B6 nutritional status. Neither age nor menarche significantly influenced erythrocyte alanine aminotransferase measurements.