Abnormal tryptophan metabolism in a family with a history of bladder cancer.

Tryptophan metabolism was studied in a family in which a sister and brother had bladder cancer. Urinary tryptophan metabolites after administration of 2 g L-tryptophan were measured in 4 sisters and 1 brother, all free of disease when studied. One sister with and 2 without histories of bladder cancer had significantly elevated levels of kynurenine, acetylkynurenine, and 3-hydroxykynurenine. Administration of 100 mg pyridoxine hydrochloride returned the tryptophan metabolism to normal in these 3 individuals. One brother with a 1 sister without bladder cancer had normal metabolism. A repeat study 2 years later confirmed the abnormal metabolism in the 3 sisters. Two sisters with abnormal tryptophan metabolism were given 200 mg L-kynurenine sulfate orally to bypass the effects of tryptophan oxygenase activity. Both excreted elevated levels of kynurenine and 1 excreted elevated levels of 3-hydroxykynurenine.

Increased plasma pyridoxal 5'-phosphate and vitamin B6 in male adolescents after 4500-meter run.

To investigate the effect of running on vitamin B6 metabolism, plasma pyridoxal 5'-phosphate and total vitamin B6 levels were determined in male adolescent trained athletes before and immediately after a 4500-m run. Six to seven subjects were studied twice during the fall and once during the spring training seasons. A mean increase in pyridoxal 5'-phosphate of 0.77 +/- 0.31 to 1.83 +/- 0.77 nmol/100 ml of plasma was observed after the three runs (p less than 0.01). Similarly, significant increases (p less than 0.05) in plasma total vitamin B6 were seen in all three runs. These increases were not solely due to changes in plasma volume. From urine samples collected on two runs, urinary 4-pyridoxic acid excretion in this group of adolescents was found to be similar to that reported for male adults. While changes in plasma glucose were not significantly correlated with changes in vitamin B6 metabolites, it is hypothesized that the significant changes in vitamin B6 metabolites found in this study were related to an increased need for cofactor for gluconeogenesis. The changes found in this study do not provide evidence for or against an increased need for vitamin B6 in persons that exercise, but does show, for the first time, that exercise in the form of long distance running dramatically alters plasma levels of pyridoxal 5'-phosphate.

Acute ingestion of glucose decreases plasma pyridoxal 5'-phosphate and total vitamin B-6 concentration.

The effect of the acute ingestion of glucose on the concentration of pyridoxal 5'-phosphate (PLP) and total vitamin B-6 (TB6) in plasma was studied. Five males and four females were given 1 g D-glucose/kg body wt. A blood sample was collected at 0-10 min and 0, 0.5, 1, 2, 3, 4, and 5 h and the plasma was analyzed for PLP and TB6. There was a significant decrease in both plasma PLP and TB6 (p less than 0.05) at 2 h. All nine subjects exhibited a decrease, and by 5 h the mean change from fasting was 8-10 nmol/L for PLP and 8-12 nmol/L for TB6 (an 18-21% decrease from that when fasting). Ingestion of 300 mL water in four subjects resulted in a mean decrease of 3.4 nmol PLP/L plasma and indicated that some but not all of the decrease may have been due to fluid ingestion per se. Ingestion of glucose is associated with a decrease in both circulating plasma PLP and TB6; therefore, carbohydrate ingestion should be considered when plasma PLP and TB6 concentrations are used to evaluate vitamin B-6 status. In addition, fasting blood samples should be used when evaluating vitamin B-6 status.

Vitamin B-6 status and bioavailability in vegetarian women.

It has been hypothesized that the vitamin B-6 status of vegetarians and nonvegetarians may differ in relation to bioavailability of vitamin B-6. Fasting blood samples and 24-h urine collections were obtained from 13 Seventh-day Adventist (SDA) vegetarian and 16 non-SDA nonvegetarian women aged 50-83 y. The two groups were further subdivided into vitamin users and nonusers. Dietary intake was estimated from a 3-d diet record. Plasma pyridoxal 5'-phosphate (PLP) was measured by an enzymatic method. Vitamin B-6 intakes were similar and provided 85% of the RDA for both groups. The vegetarians consumed significantly more crude fiber than the nonvegetarians. No significant differences were found between the two groups for plasma PLP, urinary 4-pyridoxic acid, and urinary vitamin B-6 among vitamin nonusers or for age categories within groups. There appeared to be no adverse effect of fiber on the availability or metabolism of vitamin B-6 between these free-living groups.

The effect of dietary citrus pectin on the excretion of human fecal neutral and acid steroids and the activity of 7alpha-dehydroxylase and beta-glucuronidase.

The purpose of this study was to investigate the effects of citrus pectin on human fecal neutral and acid steroid excretion and beta-glucuronidase and 7alpha-dehydroxylase activity. Eight healthy male subjects (age 20 to 27 yr) were used in a switchback design with or without 15 g citrus pectin added to a mixed low fiber diet. There were three successive 18-day periods preceded by a 4-day adjustment period. Half of the subjects followed a pectin-nonpectin-pectin protocol and the other half followed a nonpectin-pectin-nonpectin protocol. Fecal samples were collected throughout the study under anaerobic conditions. Compared to the control diet, mean fecal weight, percentage moisture, transit time, and fecal fat for both groups of subjects were not significantly different by analysis of variance when subjects were fed pectin diet. Mean beta-glucuronidase activity was increased (35%) when subjects were fed the pectin. Mean 7alpha-dehydroxylase activity showed no definite trend. Mean neutral steroid concentration was slightly decreased (8%) when the pectin diet was fed but total excretion was unchanged. End of period neutral steroid concentration was decreased 9% and total excretion was decreased 3.5%. Mean acid steroid concentration was not changed but total excretion was increased (11%) on the pectin diet. End of period acid steroid concentration and excretion was increased 6% on the pectin diet. This study shows that there were interrelationships between dietary pectin, neutral and acid steroid metabolism, and bacterial enzyme activity.

Effect of high dose ascorbic acid on vitamin B6 metabolism.

The influence of ascorbic acid intake on vitamin B6 metabolism in humans was determined in three separate studies. Five subjects in study I and two subjects in study II received 0.5 ( 2 days) and 1 g (7 days) doses of L-ascorbic acid (AA), respectively, before supplementation with 2 mg of pyridoxine hydrochloride (PN-HCl). From daily diet records the percentage of the intake of vitamin B6 excreted as urinary 4-pyridoxic acid (4PA) was calculated. Because of the variability in vitamin B6 intake, study III was conducted with four male and four female subjects, who received identical meals on days 2, 3, 9, and 10 and 1 g of AA on days 4 to 10. Two milligrams of PN.HCl were given the day before and the last day of AA administration. In contrast to studies I and II, where excretion of 4PA appeared to increase on the day of PN.HCl supplementation plus AA compared to pre-AA, urinary 4PA excretion in the eight subjects of study III was not significantly different when the same PN.HCl supplemented pre-AA and post-AA days were compared. Also, the fasting plasma pyridoxal 5'-phosphate level was not significantly altered when AA was administered. It is concluded that short-term AA supplementation did not alter vitamin B6 metabolism.

Selenium status of vegeterians, nonvegetarians, and hormone-dependent cancer subjects.

Human blood selenium (Se) levels have been related to the types of food consumed, bioavailability of Se, and various disease states, including cancer. Some of these interrelationships were investigated in this study in Corvallis, OR (a low soil-Se region) using adult vegetarian and omnivorous subjects, some of whom had hormone-dependent cancer. The study groups were comprised of 48 Seventh-day Adventist vegetarians, 16 Seventh-day Adventist nonvegetarians, 52 non-Seventh-day Adventist nonvegetarians, and 16 nonvegetarian hormone-dependent cancer subjects. Fasting blood samples and 3-days dietary intake information were obtained from each subject. Whole blood Se levels, measured fluorimetrically, correlated positively with dietary protein, riboflavin, niacin, and oleic and linoleic acids but not with 11 other nutrients. Due to limited literature values, dietary Se could not be assessed. There was no significant difference in blood Se values between the four groups (which ranged from 0.069 microgram Se/ml for Seventh-day Adventist nonvegetariants to 0.112 +/- 0.050 microgram Se/ml for non-Seventh-day Adventists nonvegetarians and nonvegetarian hormone-dependent cancer patients). All values were well below averages reported for other regions of the United States. These data suggest a relationship between blood Se and the consumption of meat, milk, and cereal products, but it is not simply a difference between the vegetarian and nonvegetarian diets.

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

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.

Vitamin B-6 status of school-aged patients with phenylketonuria.

A triad of measures of vitamin B-6 (B6) status (diet, plasma, and urine) was evaluated in 15 patients with phenylketonuria (PKU) and six control subjects (6-17 y): 1) 4-d reported dietary intakes of protein and B6; 2) fasting plasma concentrations of pyridoxal 5'-phosphate (PLP), total B6 (TB6), and alkaline phosphatase (AP) activity; and 3) 24-h urinary excretions of TB6 and 4-pyridoxic acid (4-PA). Compared with control subjects, patients had a significantly reduced mean protein intake (P < 0.001) and increased mean B6 intake (P < 0.05). Mean dietary B6:protein in patients, 0.043 mg/g protein, was over twice that of control subjects, 0.018 mg/g protein (P < 0.001). Mean plasma PLP and PLP/TB6 in patients were significantly increased compared with control subjects (P < or = 0.05). As a percent of B6 intake, mean urine TB6 was similar between the groups (6.8% patients vs 6.5% control subjects). These findings, along with a lower mean plasma AP activity in patients, support the possibility of a reduced turnover of the vitamin in PKU.

Changes in vitamin B-6 status indicators of women fed a constant protein diet with varying levels of vitamin B-6.

Changes in vitamin B-6 status indicators were evaluated in vitamin B-6-replete subjects. Ten young women consumed diets providing 85 g protein/d and 1.03, 1.33, 1.73, and 2.39 mg vitamin B-6/d for 12 or 15 d during four successive diet periods; in a second study, six women were fed diets providing 85 g protein/d and 0.84, 1.14, and 2.34 mg vitamin B-6/d for 10 or 12 d during three successive diet periods. Vitamin B-6 status indicators showing significant differences among intakes included urinary excretion of 4-pyridoxic acid and total vitamin B-6, pyridoxal 5'-phosphate and total vitamin B-6 in plasma, and xanthurenic acid excretion after a 2-g L-tryptophan load. Significant correlations were found between vitamin B-6 intake and 4-pyridoxic acid, total vitamin B-6, plasma pyridoxal 5'-phosphate, plasma total vitamin B-6, erythrocyte alanine aminotransferase percentage stimulation and postload excretion of xanthurenic acid and volatile amines (kynurenine plus acetylkynurenine). Depending on the indicator, between 20% and 70% of the subjects had inadequate values for 4-pyridoxic acid, total vitamin B-6, plasma pyridoxal 5'-phosphate, and erythrocyte alanine aminotransferase percentage stimulation at a vitamin B-6 intake of 1.33 mg/d (0.016 mg vitamin B-6/g protein). A ratio of dietary vitamin B-6 to protein > 0.016 mg/g is required for adequate vitamin B-6 status in women.

Vitamin B-6 metabolism as affected by exercise in trained and untrained women fed diets differing in carbohydrate and vitamin B-6 content.

To assess the effect of exercise on vitamin B-6 metabolism in women, five young-trained, five young-untrained, and five postmenopausal-untrained women were alternately fed four diets and then exercised (80% VO2 max; 20 min) after each diet. The following diets were fed: 2 wk moderate carbohydrate (CHO) (49%) (2.3 mg B-6); 1 wk high CHO (64%) (2.4 mg B-6); 2 wk moderate CHO + B-6 (10.3 mg B-6); 1 wk high CHO + B-6); 1 wk high CHO + B-6 (10.4 mg B-6). Blood was drawn pre- and postexercise and post-30 min and post-60 min of exercise and analyzed for plasma pyridoxal 5'-phosphate (PLP) and total B-6. Twenty-four-hour urines were analyzed for 4-pyridoxic acid and urinary B-6. PLP and total B-6 increased significantly with exercise and decreased significantly from post- to post-60 min for all diets. Four-pyridoxic acid increased significantly from the preexercise day to the day of exercise for all diets. Although there was a significant change in B-6 metabolism with exercise, neither training, increased CHO, nor age had an effect on this change.

Effect of oral contraceptives and vitamin B6 supplements on alanine and glycine metabolism.

Plasma alanine or glycine concentrations and blood pyruvate were studied before and after oral administration of the two amino acids to women using estrogen-containing oral contraceptives and to a control group of women. Thirty oral contraceptive users and 14 controls received alanine loads (200 mg/kg of body weight). The two groups had similar fasting plasma alanine levels, but the fasting blood pyruvate was elevated in the contraceptive steroid-treated women. After alanine ingestion, the increases in plasma alanine were significantly lower in the oral contraceptive users. Both groups showed a rise in blood pyruvate; there were no differences in the increments above fasting values. Treatment with pyridoxine hydrochloride, 25 mg for 4 weeks, had not effect on the responses of 11 oral contraceptive users to alanine loading. Twenty-four oral contraceptive users and 14 controls were studied before and after a glycine load (140 mg/kg of body weight). The fasting plasma glycine levels were similar, but lesser increases after ingestion of the amino acid occurred in the oral contraceptive-treated group. Blood pyruvate concentrations in both oral contraceptive users and controls were unaffected by oral glycine loads.

Metabolism of methionine in oral contraceptive users and control women receiving controlled intakes of vitamin B6.

The metabolism of methionine was studied in 10 control and in 14 women using estrogen-containing oral contraceptives during 28 days of vitamin B6 deficiency and then for another 28 days while ingesting the same diet with daily supplements of 0.8, 2.0, or 20.0 mg of pyridoxine hydrochloride. Urinary cystathionine excretion after a 3-g load of L-methionine increased promptly in both groups and continued to increase throughout the 28 days of vitamin B6 depletion; there was no significant difference in the amount excreted by controls and oral contraceptive users. Two milligrams of pyridoxine-HCl restored the cystathionine excretion to predepletion levels within three to four weeks for both control and oral contraceptive users. Daily supplements of 0.8 mg of pyridoxine-HCl for as long as four weeks failed to restore cystathionine excretion to normal levels for either controls or contraceptive users; supplements of 2.0 mg met the vitamin B6 requirements for both groups. Urinary methionine, cysteine sulfinic acid, and taurine excretion did not differ significantly between the two groups at any time. The data indicate that oral contraceptive users are not generally different from non-users with respect to vitamin B6 requirements as evidenced by methionine metabolism.

Effect of oral alanine loads on the serum triglycerides of oral contraceptive users and normal subjects.

The effect of orally administered L-alanine loads on serum triglycerides, and plasma insulin and glucose, was studied in 23 women using an estrogen-containing oral contraceptive and 13 healthy female controls. Oral contraceptive users had significantly higher fasting serum triglycerides than the controls. Serum triglycerides concentrations udnerwent little changes in the controls after alanine ingestion, whereas the oral contraceptive users showed increases which were maintained throughout the 3-hr sampling period. The two groups had similar elevations in plasma insulin after alanine loading; the glucose concentrations were unchanged. The changes in serum triglycerides may have resulted from increased metabolism of alanine to pyruvate, and its incorporation into lipids under the stimulus of elevated insulin levels.

PIP: 23 women using various combined oral contraceptive (OC) preparations were studied for the effect of oral L-alanine loads on serum triglycerides and plasma insulin and glucose levels. Fasting serum triglyceride levels were significantly (p less than .001) higher in women taking OCs than in the 13 control subjects. OC users also had significantly (p less than .001) higher serum triglyceride levels at all test times following alanine loading than controls. There were no marked differences between the preparations used. Increases in plasma insulin after alanine loading were similar for users and nonusers, while glucose concentrations were unchanged. It is suggested that the alteration in serum triglycerides may have been due to an increase metabolism of alanine to pyruvate, and its incorporation into lipids under insulin stimulus.

The effects of subject-selected high carbohydrate, low fat diets on glycemic control in insulin dependent diabetes mellitus.

In the present study, six women with insulin dependent diabetes mellitus (IDDM) were assigned to begin either a control diet containing 45% of the calories as carbohydrate, 40% fat, and 15% protein for four weeks, or a high carbohydrate, low fat diet with 65% carbohydrate, 20% fat, and 15% protein for six weeks. All subjects completed both periods in a cross-over experimental design. Individual menus varied, and were subject-selected from a calculated exchange list consisting of conventional food items. Subjects selected an equal distribution of carbohydrate from simple and complex sources during both dietary periods, and dietary fiber intake was only modestly greater during the high carbohydrate diet (50 g) than in the control diet period (28 g). No significant changes occurred in any measures of glycemic control between the control and high carbohydrates diets; fasting serum glucose 215 vs 213 mg/100 ml; preprandial serum glucose 214 vs 200 mg/100 ml; 24 hour urine glucose 36 vs 31 g/day; and glycosylated hemoglobin 10.3 vs 10.5% Hb A1, respectively. Similarly, insulin dose was unchanged during the control (38 IU/day) and experimental (38 IU/day) periods. These findings indicate that the application of present dietary recommendations to persons with IDDM in a realistic clinical setting led to neither an improvement nor a deterioration of glycemic control.

Plasma pyridoxal 5'-phosphate concentration and dietary vitamin B-6 intake in free-living, low-income elderly people.

Free-living, elderly persons (aged greater than or equal to 60 y, n = 198) were recruited to determine the effects of age, sex, health status, dietary vitamin B-6 intakes, and B-6 supplement use on plasma pyridoxal 5'-phosphate (PLP). Vitamin B-6 intakes were determined from 3-d diet records; supplementation was based on self-reported brand and frequency data. Fasting blood samples were analyzed for PLP. Subjects were primarily low-income Caucasians. There was no linear relationship between dietary vitamin B-6 intake, age, sex or health status, and PLP while accounting for supplemental vitamin B-6 use. PLP, however, was negatively correlated with age (p less than 0.001) in individuals with PLP values between 32 and 90 nmol/L. Vitamin B-6 status was low (PLP less than 32 nmol/L) in 32% of this elderly population (n = 198) and could be attributed to low dietary vitamin B-6 intakes and/or the presence of health problems reported to alter vitamin B-6 status. This research suggests that low vitamin B-6 status is prevalent in low-income, elderly persons, especially those with multiple health problems.

The composition and nutritional adequacy of subject-selected high carbohydrate, low fat diets in insulin-dependent diabetes mellitus.

The composition and nutritional adequacy of subject-selected high carbohydrate, low fat diets were investigated in six women with insulin-dependent diabetes mellitus. Subjects were randomly assigned to begin either the experimental diet with 65% carbohydrate, 20% fat, and 15% protein for 6 wk, or a control diet with 45% carbohydrate, 40% fat, and 15% protein for 4 wk. All subjects completed both dietary periods in a cross-over experimental design. Subjects were allowed free selection in their choice of carbohydrate-rich foods. The resulting selections produced diets with 51% simple and 49% complex carbohydrates and 50 g of dietary fiber during the experimental diet. Similar proportions were also selected during the control diet. Blood chemistries revealed no significant changes in thiamin, riboflavin, vitamin B6, pyridoxal 5'-phosphate, ascorbate, vitamin E, calcium, selenium, or zinc concentrations between the two dietary periods. With the exception of vitamin B6, all vitamin and mineral values were within normal respective ranges. Vitamin B6 status, as assessed by pyridoxal 5'-phosphate, were below or just above the levels of marginal deficiency (2.2 nmol/100 ml) in four of the six individuals, but the lower level observed occurred independent of the dietary treatments. The present study demonstrates that subject-selected high carbohydrate, low fat diets were much lower in complex carbohydrates and fiber than diets previously tested. In addition, the concentration of several nutrients did not appear to be adversely affected by these diets.

Vitamin B6 requirements of women using oral contraceptives.

Fifteen women who used combined estrogen-progestogen oral contraceptives and nine control women were given a vitamin B6-deficient diet for 4 weeks and the same diet supplemented with 0.8, 2.0, or 20.0 mg of pyridoxine hydrochloride for an additional 4 weeks. At weekly intervals a variety of indices of vitamin B6 nutrition were measured to determine rates of depletion and repletion. The tryptophan load test (2.0 g) was significantly different in the contraceptive users. However, other indices, including urinary cystathionine (3.0 g L-methionine load), urinary 4-pyridoxic acid, plasma phosphate, and erythrocyte alanine and aspartate aminotransferases, were not significantly different. Since altered tryptophan metabolism persisted in contraceptive users even when other indices of vitamin B6 nutrition were normal, we suggest that the use of oral contraceptives specifically affects tryptophan metabolism by some means other than through a vitamin B6 deficiency.

PIP: This study was designed to evaluate the effect of oral contraceptive use on the requirement for Vitamin-B6 and the rate at which such persons became depleted of Vitamin-B6 while ingesting a diet low in this vitamin. The same indices were used to measure the rate at which these persons became repleted when the diet was supplemented by pyridoxine. Before testing, women using estrogen-containing oral contraceptives were shown to excrete increased amounts of tryptophan metabolites after a tryptophan load test as compared with women not taking oral contraceptives. Elevated levels of 3-hydroxyanthranilic acid were also excreted in urines of such subjects. There were 15 young women subjects who had used estrogen-progestogen oral contraceptives for at least 6 months and 9 women who had not used any oral contraceptive. All were given a Vitamin-B6 deficient diet containing only 1.9 mg of pyridoxine equivalent per day for 4 weeks and then the same diet supplemented with .8-20 mg of pyridoxine hydrochloride for 4 more weeks. Weekly indices of Vitamin-B6 nutrition were determined. Only the tryptophan load test was significantly different in contraceptive users. Urinary cystathionine, urinary 4-pyridoxic acid, plasma phosphate, erythrocyte alanine, and aspartate aminotransferases were not significantly changed. The altered tryptophan metabolism persisted in contraceptive users after other indices of Vitamin-B6 nutrition became normal. Therefore, this altered tryptophan metabolism in oral contraceptive users is considered to be due to other factors than Vitamin-B6 deficiency. This effect may be primarily dependent on the activity of tryptophan oxygenase although other enzymes may also be factors. It is suggested that the use of estrogen-containing oral contraceptives may produce a Vitamin-B6 deficiency in some persons but this is not considered consistent or to have been shown by these experiments. The amount of Vitamin-B6, as pyridoxine, needed to maintain normal levels of indices, other than tryptophan, was between .8 and 2 mg/day. Data suggest that any alteration of Vitamin-B6 need by the use of combined estrogen-progestogen preparations is a minor one of doubtful clinical significance in the majority of women taking these steroids.

Effect of oral contraceptives and vitamin B6 deficiency on carbohydrate metabolism.

Oral glucose tolerance, urinary xanthurenic acid excretion, and plasma pyridoxal phosphate concentrations were determined in nine women taking oral contraceptives and in four controls. The tests were repeated after 4 weeks ingestion of a vitamin B6-deficient diet, and again after pyridoxine supplementation. Vitamin B6 deficiency, as judged by an increased xanthurenic acid excretion and reduced plasma pyridoxal phosphate, was associated with a deterioration in the glucose tolerance of the contraceptive steroid-treated group despite normal or elevated plasma insulin levels. This abnormality was reversed by pyridoxine. There was no change in the glucose tolerance of the vitamin B6-deficient controls. The observed pyridoxine-responsive alteration in carbohydrate metabolism may involve the complexing of insulin with xanthurenic acid with a consequent loss of biological activity. In addition, oral contraceptives may enhance gluconeogensis.

Urinary 4-pyridoxic acid, plasma pyridoxal phosphate, and erythrocyte aminotransferase levels in oral contraceptive users receiving controlled intakes of vitamin B6.

Fifteen women who had used combination type oral contraceptives (estrogen plus progestogen) and 9 control women who had never used these agents were given a diet deficient in vitamin B6. After 1 month, this diet was supplemented daily with 0.8, 2.0 or 20.0 mg of pyridoxine hydrocholride for an additional month. At weekly intervals, measurements were made of urinary 4-pyridoxic acid, plasma pyridoxal phosphate, and erythocyte alanine and aspartate aminotransterases. No significan differences were observed between oral contraceptive users and controls in any of the above measured indices. The data suggest that if the use of oral contraceptives of the combined estrogen-progestogen type does alter the requirement for vitamin B6, the effect is a mild one and of doubtful clinical significance to the majority of women taking these steroid preparations. The amount of vitamin B6 (as pyridoxine) needed to maintain normal levels of the above indices of vitamin B6 nutrition in these subjects were between 0.8 and 2.0 mg/day.