Vitamin B-6 requirement and status assessment: young women fed a depletion diet followed by a plant- or animal-protein diet with graded amounts of vitamin B-6.

The vitamin B-6 requirement of young women consuming a high-protein diet (1.55 g/kg body wt) and the effect of protein quality on this requirement was studied. In addition, the response of clinical, functional, and biochemical measures of vitamin B-6 nutriture to short-term depletion and step-wise repletion of vitamin B-6 were evaluated. Eight healthy young women resided in a metabolic unit and were fed a formula depletion diet (< 0.05 mg vitamin B-6/d) for 11-28 d followed by either an animal-protein (AP) or plant-protein (PP) diet with successively increasing vitamin B-6 intakes (0.5, 1.0, 1.5, and 2.0 mg/d) for periods of 14-21 d. Animal proteins were primarily from dairy and poultry sources and plant proteins were primarily from legumes. Vitamin B-6 status measures were assessed at weekly intervals. Results showed that a PP diet does not elevate the vitamin B-6 requirement over that required for an AP diet given the high amount of dietary protein used in this study. It was also found that 0.015 mg vitamin B-6/g protein intake normalized most biochemical indexes of vitamin B-6 status (including those indicative of functional status), and that 0.020 mg/g protein normalized all biochemical measures except total urinary vitamin B-6. Adding a margin of safety to either the 0.015 or 0.020 mg/g protein intake would raise the vitamin B-6 requirement for young women above the currently recommended dietary allowance of 0.016 mg/g protein.

Biochemical assessment of vitamin B6 nutritional status in pregnant women with orolingual manifestations.

Two groups of pregnant women belonging to a low socioeconomic group, one with oral lesions and the other without lesions, were studied in the 3rd trimester of pregnancy for vitamin B6 nutritional status. Both the groups showed evidence of abnormal tryptophan metabolism, and in pregnant women with clinical signs the postload xanthurenic acid excretion in urine was higher than in the other group, suggesting a severe deficiency of vitamin B6. Treatment with vitamin B6 cured the oral lesions and also corrected the abnormalities in tryptophan metabolism. Excretion of 4-pyridoxic acid was low in both the groups and more so in women with oral lesions. Administration of tryptophan load significantly elevated the excretion of 4-pyridoxic acid in urine. These results indicated that pregnant women belonging to a low socioeconomic group were, in general, deficient in vitamin B6. In pregnant women with oral lesions the deficiency of vitamin B6 was more severe than in those pregnant women without oral lesions. Whether the severity of vitamin B6 deficiency would precipitate clinical signs like oral lesions is not yet known.

The vitamin B6 requirement in oral contraceptive users. II. Assessment by tryptophan metabolites, vitamin B6, and pyridoxic acid levels in urine.

PIP: The requirement for vitamin B6 in oral contraceptive users was studied in 8 college-age women who used combined (7) or sequential (1) oral contraceptives. The subjects and 8 controls consumed a basal diet supplemented to result in daily intake of 2.06 mg pyridoxine hydrochloride for 10 days (predepletion) and then containing only .36 mg of vitamin B6 for 32 days. After the depletion period, the diet was supplemented with pyridoxine hydrochloride to increase the intake of B6 to .96, 1.56, and 5.06 mg for 8, 9, and 7 days respectively. Complete 14-hour urine collections were analyzed for xanthurenic acid, kynurenic acids, kynurenine, and 3-hydroxykynurenine after administration of a l load-dose of 2 gm L-trytophan on days 2, 11, 18, 25, 32, 39, 43, 50 , 59, and 66 for the subjects and days 2 and 10 for the controls. Pretryptophan urine was analyzed for vitamin B6. Posttryptophan urine was analyzed for 4-pyridoxic acid. It was found that during the depletion phase the excretion of tryptophan metabolites increased significantly. Excretion dropped significantly upon supplementation with 1.56 or 5.06 mg of vitamin B6, returning values to normal. Levels of vitamin B6 and 4-pyridoxic acid in the urine decreased during depletion to be restored to normal upon supplementation with 1.56 mg/day. Since an intake of 5.0 mg vitamin B6 caused a loss of the vitamin in the urine and all levels were returned to normal with an intake of 1.56 mg, it is suggested that 1.5 mg of vitamin B6 is sufficient to meet the needs of most oral contraceptive users and that there is no significant difference in the vitamin B6 requirement of oral contraceptive users and nonusers.^ieng

Effect of oral contraceptive agents on vitamin nutrition status.

Effects of low estrogen combination type oral contraceptives on some of the biochemical parameters used for assessing vitamin nutritional status were investigated in a group of women who had used the pill for 6 to 12 months. Another group of women was examined initially and then at one or more points of time within the first 6 months of treatment. Following changes were observed in women treated with oral contraceptives: 1) increased excretion of kynurenic acid and xanthurenic acid following tryptophan load; 2) increased EGOT activity and also an increase in vitro stimulation of EGOT with added PALP; 3) increased plasma vitamin A levels; 4) fall in erythrocyte folate levels; 5) fall in erythrocyte transketolase activity with no change in vitro stimulation with TPP; and 6) fall in erythrocyte riboflavin concentration associated with a decrease in erythrocyte glutathione reductase activity and increase in vitro stimulation with FAD. Most of these changes were observed during the first few cycles of oral contraceptive treatment.