This investigation was designed to add to present understanding of vitamin B-6 (B6) metabolism during exercise. Ten women, 5 aerobically trained and 5 untrained, were fed 4 controlled diets: a moderate carbohydrate (49%) (MCHO) for 2 weeks, a high carbohydrate (63%) (HCHO) for one week, MCH0+B6 for 2 weeks, and HCH0+B6 for 1 week. A one week MCHO diet separated the non-supplemented (2.3 mg B6) and supplemented (10.3 mg B6) diets. The V02 max of each subject was determined prior to the study. An exercise test was completed on day 5 or 6 of weeks 2, 3, 6, and 7. The test consisted of 20 minutes of cycle ergometer exercise at 80% V02 max, preceded by 10 minutes of warm-up and followed by a 5-10 minute active recovery. Blood samples were collected pre exercise (pre), 2-3 minutes post (post), 30 minutes post (p30), and 60 minutes post (p60) exercise. Samples were analyzed for plasma vitamin B-6 (PB6), hematocrit, and hemoglobin. Urine was collected daily in 24-hr aliquots and samples were analyzed for 4-pyridoxic acid (4PA) and creatinine. For all diets, exercise resulted in a significant increase in PB6 from pre to post and a significant decrease from post to p60, the magnitude of the change being greater with supplementation. PB6 fell below pre levels by p60 for all exercise sessions. 4PA increased significantly from the day before exercise to the day of exercise on all diets. There was no significant effect of dietary carbohydrate on levels of PB6 or excretion of 4PA. ANOVA showed no difference between the groups for PB6 or 4PA, though the trained group had lower PBS and greater 4PA excretion throughout the study despite the controlled intake. Tissue redistribution of B6 seems to occur with exercise. The increased magnitude of change in PB6 with exercise after supplementation suggests an increased storage of the vitamin, most likely associated with glycogen phosphorylase in the muscle. Trained women may have lower levels of PB6 and greater 4PA excretion as the result of a regular exercise program. However, supplementation with B6 cannot be recommended since the status of all subjects was adequate with the diet fed. / Graduation date: 1985

The bioavailability of vitamin B-6 from four selected foods was investigated in five men, aged 22 to 25 years, who were receiving a pyridoxine supplement. The subjects received a constant diet containing 1.34 mg of vitamin B-6 throughout this five-week study, except on Saturdays and Sundays when they ate their self-chosen diets. Starting on day 6 of week 1, following a five-day adjustment period, the subjects received orally 5-mg crystalline pyridoxine supplement daily, except on Tuesday and Thursday of each week. On these two days, the subjects were given orally 0 mg or 2 mg of crystalline pyridoxine, or test doses of bananas, filberts, soybeans and beef which contained around 2 mg of vitamin B-6. Vitamin B-6 was determined by microbiological assay with Saccharomyces uvarum. Vitamin B-6 bioavailability in the test food was determined by comparing 24-hour urinary total vitamin B-6 in response to the test food doses to that excreted following a 2-mg crystalline pyridoxine dose in each subject. Compared to the 100 percent bioavailability of the 2-mg crystalline PN dose, the average vitamin B-6 bioavailability in bananas was 115 + 32% and that in filberts, soybeans and beef was 93 + 8%, 73 + 20% and 87 + 7%, respectively. The metabolism of vitamin B-6 in pyridoxine-supplemented subjects was also investigated by measuring changes in plasma total vitamin B-6 which increased and was stablized after three weeks of pyridoxine supplementation. It was concluded that urinary total vitamin B-6 in pyridoxine-supplemented subjects can be used as a measure of vitamin B-6 bioavailability from test food doses. / Graduation date: 1983

The present study was designed to investigate the effects of exercise on vitamin B-6 metabolism. Four groups of subjects (intermittent, college, untrained, and high school) consisting of nineteen male and two female individuals, participated in the study. The subjects exercised either on a bicycle ergometer, by running three 1500 meter intervals, or both. Blood samples drawn prior to exercise (pre), after exercise (post), and 30 minutes after exercise (30 minute post), were analyzed for plasma pyridoxal 5'-phosphate (PLP), plasma B-6 (PB6), glucose, hemoglobin and hematocrit. A 24-hr urine collection the day before and the day of exercise was analyzed for urinary B-6 (UB6), 4-pyridoxic acid (4PA), creatinine, and urea nitrogen. The dietary intake of the four groups was greater than the RDA in vitamin B-6, riboflavin, thiamin, niacin, vitamins A and C, calcium and iron. The B-6/protein ratios of the college and untrained groups were adequate while the high school group's ratios were considered inadequate. The bicycle ergometer had a significant effect on the plasma PLP levels of the college and untrained groups (P< 0.005) and PB6 levels of the college group following exercise (P< 0.005). The 30 minute post plasma PLP levels were significantly lower for the college group (P< 0.005). During the run, the college group had significantly higher post exercise levels of plasma PLP (P< 0.005) and PBS (P< 0.005} as compared to the pre exercise sample. The high school group also had significantly higher levels of plasma PLP following, exercise for all three runs (P< 0.005, P< 0.025, and P< 0.01, respectively) as well as higher PB6 levels (P< 0.025, P< 0.01, and P< 0.025, respectively). The college athletes had a greater percent change in plasma PLP (P < 0.01) from the pre to post sample during the run as compared to the high school athletes. Urinary B-6 and 4PA were not significantly altered during either exercise suggesting a shift in PLP and the unphosphorylated forms of vitamin B-6 from one compartment to another. The significantly higher levels of plasma PLP and PB6 following exercise were attributed to an increased utilization of glycogen phosphorylase in the skeletal muscle with a subsequent release of PLP. / Graduation date: 1982

The effect of pyridoxine (PN) supplementation on the activities of erythrocyte alanine aminotransferase (EAlaAT) and aspartate aminotransferase (EAspAT) was observed in five men, aged 22 to 25 years. The subjects received a constant diet containing 1.34 mg of vitamin B-6 Monday through Friday of each week during this five-week study. Starting on day 6 of week 1, the subjects were given orally 5 mg PN daily, except on Tuesday and Thursday of each week when they were given either no PN or 2 mg of vitamin B-6 in the form of crystalline PN or as food. Basal and pyridoxal phosphate (PLP)-stimulated EAlaAT and EAspAT activities were determined weekly. Both basal and PLPstimulated activities of the two enzymes increased after only three days of PN supplementation and continued to increase throughout the four weeks of PN supplementation; percent stimulation by PLP added in vitro decreased concomitantly. It is suggested that the binding of PLP to erythrocyte apoaminotransferases may be another reservoir for vitamin B-6. / Graduation date: 1982

The effect of pyridoxine (PN) supplementation on lymphocyte responsiveness was investigated in 15 elderly volunteers (aged 65-81 years) by measuring lymphocyte proliferation to T and B cell mitogens, lymphocyte subpopulations with monoclonal antibodies (T3, T4, T8) and plasma pyridoxal 5'-phosphate (PLP) concentration at pre-supplementation and after 1 and 2 months of daily supplementation. Eleven subjects received 50mg of PN-HC1 and 4 received a placebo. Dietary histories were also evaluated for Intake of vitamin B-6, protein and kilocalories. Mitogens used for the stimulation of lvmphocyte proliferation were phytohemagglutinin (PHA), concanavalln A (Con A), pokeweed mitogen (PWM), and Staphylococcus aureus Cowain I (SAC). Plasma PLP was measured by a radio tracer method. Before supplementation, mean PLP of the 15 subjects was 31.7 +/- 14.1 nM; 5 PN and 3 placebo treated subjects had low PLP levels. After 1 and 2 months of PN-HCl supplementation, the PLP levels Increased by 195 +/-88 nM and 201 +/-84 nM, respectively. Lymphocyte proliferation In response to PHA, PWM, and SAC Increased significantly (p < 0.05) with PN supplementation. Among PN-treated subjects, Ivmpbocyte blaatogenesls was significantly greater In response to Con A and PWM in individuals whose initial PLP was low. Percentages of T3+ and T4+, but not T8+ cells increased significantly In PN-treated individuals. These results suggest that vitamin B-6 status is important in maintaining immunocompetence in the elderly. / Graduation date: 1986

The study was designed to indirectly understand muscle glycogen utilization during prolonged exercise when either glucose, fructose, or water is ingested. Eight trained adult males exercised on a cycle ergometer at 58±7% of V02 max for 2 h on 2-4 occasions. At 0 minutes of exercise and at 30-minute intervals throughout the exercise, the subjects ingested 200mL of fluid containing either glucose, fructose, or plain water in a double-blind, randomized fashion. The carbohydrate (CHO) fluid concentration was based on each subject's body weight (BW): Ig CHO X kg⁻¹ BW X L⁻¹ water and ranged from 5.8-9.2% (average=7.5%) of BW. Blood samples were collected from subjects at rest and immediately prior to fluid ingestion during exercise and analyzed for hematocrit, hemoglobin, and plasma levels of glucose, lactate, and pyridoxal 5'-phosphate (PLP). ANOVA showed no significant difference among treatments at any time of exercise for mean plasma lactate and PLP levels (p > 0.05). Although not significant, mean plasma lactate and PLP concentrations tended to be lower when glucose was consumed as compared to fructose and water. The mean plasma glucose level, however, uas significantly different among treatments at specific time points of exercise (p < 0.05). During exercise, mean plasma glucose decreased, and there was a higher plasma glucose level when glucose and fructose fluids were ingested as compared to water. At 60 minutes of exercise, this difference uas evident for both glucose and fructose ingestion (p < 0.05). At 90 and 120 minutes of exercise, fructose ingestion produced a significantly higher mean plasma glucose level than either water or glucose ingestion (p < 0.05). It is hypothesized that the higher plasma glucose levels provided a greater blood glucose supply to working muscles, thereby sparing muscle glycogen stores. The findings indicate that for the long-term exerciser, consumption of a 5.8-9.2% fructose solution may promote less muscle glycogen utilization than either glucose or water, thereby possibly increasing endurance. / Graduation date: 1986

The objectives of this study were a) to determine if pyridoxine (PN) supplementation increases the rate at which plasma urea and ammonia return to basal levels, following exercise, b) to determine, by open circuit calorimetry, the utilization of carbohydrates, and c) to further understand vitamin B-6 metabolism during and following strenuous exercise. Six male athletes (age 26 ± 5 years and VO₂ max 66.4 ± 6.9 ml/kg/min) exercised for 1 hour on a cycle ergometer at 72% VO₂ max at two points during a 17 day study. For the first 8 days subjects received daily a placebo solution, while during the next half they received a PN dose (20 mg). Subjects consumed a constant diet the day before, day of, and day after the exercise test. Blood samples were taken the day of the exercise test at fasting (Fl), pre-exercise (PE), during exercise (DE), 1 min post exercise (I'P), 6 hour post exercise (6hP), and the day after the exercise test at fasting (F2). Plasma was analyzed for ammonia, urea, and pyridoxal 5'-phosphate (PLP). ANOVA showed no significant difference between treatments for either plasma ammonia or urea. While there was a significant increase (p<0.001) in plasma ammonia levels over time with the placebo, with supplementation the increase over time was not significant. With PN supplementation, plasma PLP levels were significantly correlated (p<0.05) with plasma ammonia levels at I'P. A slight decrease in plasma urea concentration was observed with the PN treatment at PE, DE, I'P, and 6hP. It was concluded that PN may reduce adverse consequences of plasma ammonia and urea seen with exercise. On the other hand, pyridoxine supplementation may produced a shift in the utilization of substrates of the subjects. Metabolic rate results showed that the contribution of carbohydrates as a energy source increased from 43.5 ± 13.7% with the placebo, to 52.0 ± 6.7% with the PN treatment (not significantly different). This observation lead to the conclusion that PN supplementation decreases glycogen stores compared to the glycogen stores without supplementation. Since the findings from this study suggest slightly more rapid plasma ammonia and urea restoration but decreased glycogen stores, they do not provide evidence for or against an increased need for vitamin B-6 in persons that are involved in strenuous exercises of medium duration. / Graduation date: 1988

Four studies were conducted to evaluate the effect of varying levels of vitamin B-6 (B6), protein and pyridoxine glucoside (PNG) on B6 status and requirements of women. In the first two studies, women were fed a constant protein diet and vitamin B-6 intakes of 0.84 to 2.39 mg/d during 10- to 15-day experimental periods. Significant differences among intake levels were found in urinary 4-pyridoxic acid (4PA) and total vitamin B-6 (UB6), plasma pyridoxal 5'-phosphate (PLP) and total vitamin B-6 (TB6), and urinary xanthurenic acid (XA) following a tryptophan load. Significant correlations were found between B6 intake and 4PA, UB6, plasma PLP, TB6, erythrocyte alanine aminotransferase (EALT) percent stimulation, and postload urinary XA and volatile amines (VA, kynurenine plus acetylkynurenine). More than 1.33 mg B6/d (> 0.016 mg B6/g dietary protein) was required for adequate B6 status. In a third study, nine women were fed diets providing 1.25 mg B6/d and three levels of protein (0.5, 1.0 and 2.0 g/kg body weight), for 14 days each. Significant differences in urinary 4PA, plasma PLP, and postload urinary VA were found among protein levels. Nitrogen intake was significantly negatively correlated with urinary 4PA and plasma PLP, and positively correlated with EALT percent stimulation and postload urinary kynuremc acid (KA), XA and VA. Compared to men in a previous study, women excreted a greater percentage of B6 intake as 4PA, had lower plasma PLP and greater amounts of postload urinary tryptophan metabolites. At least 0.020 mg B6/g protein was required for adequate status. In a fourth study, nine women were fed diets with a high (27%) or low (9%) percentage of the B6 intake as pyridoxine glucoside, a form known to have reduced bioavailability, for 18 days each. Urinary 4PA and UB6, plasma TB6 and red blood cell PLP were significantly lower, and fecal B6 was significantly higher during the high PNG diet. The decrease in B6 status indicators on the high PNG diet suggested a loss of 15 to 18% of the total B6 intake. Taking into account bioavailability and gender differences in the effect of dietary protein, and including a safety margin, the RDA for B6 for women should be at least 0.020 mg/g dietary protein. / Graduation date: 1996

Graduation date: 1980

The effect of vitamin B-6 (B-6) status on plasma fatty acids (FA) levels and lipid metabolism was investigated in this metabolic study. Eight female subjects were fed for 28 days. For the first 7 days, they were fed a constant diet containing 2.10 mg of B-6. For the rest of the period (21 days), they were differentiated in terms of B-6 intake; 4 of them were fed a low (0.93 mg/day) and 4 a high (2.60 mg/day) B-6 diet. B-6 status indices, plasma FA concentration and lipid profile were determined. Plasma pyridoxal 5'-phosphate and total B-6 concentration (P<0.01), urinary 4- pyridoxic acid and total B-6 concentration (P<0.001) showed a significant difference between the two groups at the end of the study. Erythrocyte PLP failed to show any significant difference between the two groups throughout the diet study. There was no significant difference in the plasma FA or lipid profile between the two groups. Plasma total cholesterol (TC) of the low B-6 group decreased slightly (7 %), but was not statistically significant. When comparing day 7 and day 28 values, plasma triglycerides increased (9 %) for the high and decreased for the low B-6 group. LDL-C decreased (5 %) for the high B-6 group but did not change in the low B-6 group. HDL-C decreased slightly in both groups (~8 %). There was no clear evidence that a low intake of vitamin B-6 affects the fatty acid and lipid metabolism. Further studies are required to identify the relationship between vitamin B-6 and fatty acid and lipid metabolism in humans. / Graduation date: 1997