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: 1946

Graduation date: 1980

Thesis (Lic.)--Universidad Técnica del Norte, Facultad Ciencias de la Salud, Escuela de Nutrición y Dietética. / Reproduced from copy at BYU's Benson Institute. Includes bibliographical references (leaves 62-63).

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed September 10, 2009). Thesis advisor: Dr. Catherine Peterson. Includes bibliographical references.

Thesis (M.F.C.S.)--Bowling Green State University, 2008. / Document formatted into pages; contains viii, 56 p. Includes bibliographical references.

The purpose of this study is to show how much of the thiamin content of the noon and evening meals is contributed by meats and meat dishes which appear on the cafeteria menu, as well as the thiamin contribution of the breakfast meal to the total daily intake.

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

The purpose of this study was to examine the effect of extreme exercise on vitamin B-6 metabolism and urea nitrogen. Nine men and five women completed two 5-day trials; Trial 1 (T1) included a 50-km ultramarathon on day 4 and during Trial 2 (T2) subjects were "inactive" on day 4. During both trials, subjects consumed a diet providing men 2.0 and women 1.5 mg of vitamin B-6. With the exception of the ultramarathon, T1 activity was replicated during T2. Twenty four-hour urine collections were completed and blood was drawn pre-race (pre), mid-race (mid), post-race (post) and 60 minutes post race (P-60). On the inactive, day blood was drawn at the same intervals. Plasma was analyzed for pyridoxal 5'-phosphate (PLP), pyridoxal, 4-pyridoxic acid (4-PA), urea nitrogen (PUN), creatinine, albumin, glucose, and lactate concentration and alkaline phosphatase activity. Urine was analyzed for 4PA, creatinine, and total urinary nitrogen (TUN). During T1, compared to pre, plasma PLP concentration increased 17% at mid, decreased 5% by post, and 19% by P-60. During T2, plasma PLP concentration decreased 13% pre to P-60. During T1, plasma 4-PA concentration increased 135% and the percent dietary vitamin B-6 that was excreted as urinary 4-PA the day of the ultramarathon was higher than that excreted the day before and the day after. During T1, from pre to post mean PUN concentration increased 36.9%, and the average rate ofincrease from pre to mid, mid to post, and post to P60 was 0.5, 1.75, and 2 mg/dL/hour, respectively. During T1 on days 3, 4, and 5,88%, 100%, and 95% of nitrogen intake was excreted in the urine compared to 86%, 83%, and 84% for the same days during T2. The day of the ultramarathon, 24-hour TUN excretion was 2 g higher than the previous day. Extreme exercise of greater than six hours initially increases the plasma concentration of PLP but ultimately results in a significant decrease in plasma PLP, an increase in plasma 4-PA, and an increase in percent of dietary vitamin B-6 (as 4-PA) excreted in the urine. Additionally, the rate of change in PUN inoeases as duration increases. / Graduation date: 2001