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Biomedical subjects

J E Leklem

Publications and source records attributed to J E Leklem.

At least 37 records · Page 2Linked to original sources
PubMed1987

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.

Aged↗
PubMed1987

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.

Adult↗
PubMed1985

The effects of a high-carbohydrate low-fat cholesterol-restricted diet on plasma lipid, lipoprotein, and apoprotein concentrations in insulin-dependent (type I) diabetes mellitus.

Six women with well-defined insulin-dependent diabetes mellitus (IDDM) were studied for 4 weeks during a control diet containing 45% of the calories as carbohydrate, 40% fat (P/S ratio 0.14), 15% protein, and 580 mg of cholesterol, and for 6 weeks during a high-carbohydrate low-fat cholesterol-restricted diet with 65% carbohydrate, 20% fat (P/S ratio 1.40), 15% protein, and 62 mg cholesterol. All subjects completed both dietary periods in a crossover experimental design. Individual menus were subject-selected from a calculated exchange list containing conventional food items consistent with current American dietary patterns. The diets were well-tolerated by all subjects. Total plasma cholesterol decreased from 201 to 156 mg/100 mL (P less than 0.05) during the cholesterol-restricted diet, while total plasma triglyceride (TG) increased from 96 to 115 mg/100 mL (P less than 0.01). During this same period, very low-density lipoprotein cholesterol (VLDL-C) and VLDL-TG increased from 17 to 21 mg/100 mL (P less than 0.05) and from 59 to 76 mg/100 mL (P less than 0.001), respectively, while low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) decreased from 126 to 90 mg/100 mL (P less than 0.05) and from 50 to 39 mg/100 mL (P less than 0.05), respectively. LDL-C/HDL-C and total-C/HDL-C ratios were lower but not significantly different, and LDL-TG and HDL-TG were unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

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.

Adult↗
PubMed1985

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.

Adult↗
PubMed1985

The effect of dietary protein on the metabolism of vitamin B-6 in humans.

Eight men, aged 21-31 yr, were fed semipurified diets containing 0.5 (low), 1.0 (medium) and 2.0 (high) g protein/kg body weight; vitamin B-6 intake was kept constant at 1.6 mg/d. Each level of protein was fed for 15 d. Urinary vitamin B-6 (UB-6), urinary 4-pyridoxic acid (4-PA), plasma total vitamin B-6 (PB-6) and plasma pyridoxal 5'-phosphate (PLP) were determined every third day. Means are reported for all subjects of values determined during the second half of each period. Concentration of urinary and plasma vitamin B-6 compounds were negatively correlated with protein intake: the correlation coefficient of nitrogen intake with 4-PA was -0.69 (P less than 0.01); with PLP, -0.45 (P less than 0.05); and with PB-6, -0.48 (P less than 0.05). The decrease in UB-6 was not statistically significant. These results indicate that with increased intake of dietary protein, vitamin B-6 is retained in the body for increased catabolism of amino acids. When evaluating vitamin B-6 requirements or status in humans, protein intake must be considered.

Adult↗
PubMed1983

Nutrient intake and hormonal status of premenopausal vegetarian Seventh-day Adventists and premenopausal nonvegetarians.

The relationship between dietary nutrients and plasma estrone, estradiol-17 beta, estriol, dehydroepiandrosterone sulfate, and prolactin levels was investigated in 14 premenopausal Seventh-day Adventist vegetarian (SV) women and 9 premenopausal non-Seventh-day Adventist nonvegetarian (NV) women. The SV subjects consumed less fat, especially saturated fat, and used significantly less fried food than the NV subjects. Plasma levels of estrone and estradiol-17 beta in the SV subjects were significantly lower than in the NV subjects. SV estradiol-17 beta and estriol levels were positively correlated with linoleic acid and protein intake, while NV prolactin levels were significantly correlated with intakes of oleic and linoleic acids and total fat. The data suggest that specific dietary nutrients were related to the hormonal milieu of these SV and NV subjects.

Adult↗
PubMed1983

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.

Adult↗
PubMed1983

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.

Adult↗
PubMed1983

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.

Adolescent↗
PubMed1983

Comparative vitamin B-6 bioavailability from tuna, whole wheat bread and peanut butter in humans.

Relative bioavailability of vitamin B-6 from tuna, whole wheat bread and peanut butter was investigated in eight men. The study was divided into a 10-day adjustment and three, 14-day experimental periods in a 3 X 3 Latin square design. Vitamin B-6 intake was set at 1.6 mg/day, with 50% of the intake coming from one of the three experimental foods and 50% from a basal diet. Daily complete urine and fecal collections were made. Urine was analyzed for 4-pyridoxic acid (4PA) and vitamin B-6, fecal samples for vitamin B-6 and plasma (sampled every 5 days) for pyridoxal 5'-phosphate (PLP). Mean values +/- SD for the adjustment, tuna, whole wheat bread and peanut butter periods were: 5.65 +/- 1.76, 4.89 +/- 1.10, 3.62 +/- 0.66 and 2.80 +/- 0.50 mumol/day for 4-pyridoxic acid; 0.98 +/- 0.34, 1.05 +/- 0.20, 0.76 +/- 0.09 and 0.68 +/- 0.19 mumol/day for urinary vitamin B-6; 2.72 +/- 0.94, 3.08 +/- 0.73, 3.80 +/- 0.78 and 4.42 +/- 1.03 mumol/day for fecal vitamin B-6 and 65.0 +/- 23.30, 64.8 +/- 29.80, 49.3 +/- 14.40 and 48.4 +/- 20.20 nM for plasma pyridoxal 5'-phosphate, respectively. 4PA and urinary vitamin B-6 excretion were significantly (P less than or equal to 0.01) higher in the tuna period than in either the whole wheat bread or peanut butter periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

The effect of wheat bran on the bioavailability of vitamin B-6 in young men.

The effect of cooked wheat bran on the bioavailability of vitamin B-6 (B-6) was determined in 10 men, aged 20 to 35 years. The subjects consumed a constant diet with and without the addition of 15 g wheat bran during three successive 18-day periods in a switch-back design. Half of the subjects received the additional bran during periods 1 and 3; the other half consumed the bran during period 2. The bran and nonbran diets supplied, respectively, 1.69 and 1.66 mg of B-6 daily. Plasma total B-6 and pyridoxal phosphate (PLP), urinary 4-pyridoxic acid (4-PA), and urinary and fecal B-6 were determined at regular intervals during each period. Bran significantly increased fecal B-6 (P less than 0.05) and decreased urinary 4-PA (P less than 0.01). Bran also significantly depressed plasma B-6 (P less than 0.01) and PLP (P less than 0.05). These results indicate that the addition of 15 g of wheat bran to the diet decreased the bioavailability of B-6. Since this decrease was modest, never exceeding 17% (based on urinary 4PA and B-6), this amount of bran will not adversely affect B-6 status when intake of the vitamin is adequate.

Adult↗
PubMed1983

Dietary status of Seventh-day Adventists and nonvegetarians.

The dietary intakes of Seventh-day Adventist (SDA) vegetarians and nonvegetarians, as well as of non-SDA nonvegetarians, were generally adequate. However, even though iron and vitamin B6 intakes exceeded 100% and 90% of the RDAs for all men, 26% and 19% of the women were consuming less than 60% of the RDAs for iron and vitamin B6.

Adult↗
PubMed1982

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.

Adult↗
PubMed1981

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.

Adult↗
PubMed1980

The metabolism of small doses of vitamin B-6 in men.

The metabolism of small doses of pyridoxine (PN) and of equimolar doses of PN, pyridoxal (PL) and pyridoxamine (PM) was studied in five men. Fasting subjects were given 0, 0.5, 1, 2, 4 and 10 mg pyridoxine HCl and 19.45 mumoles of PN, PM and PL; one dose was administered a week. Plasma total vitamin B-6 (B-6) and pyridoxal phosphate (PLP), and urinary B-6 and 4-pyridoxic acid (4PA) were determined in timed blood and urine samples collected after each dose. The n doses had a significant P less than 0.01) overall effect on all of these measurements; the relationship between PN level and the subjects' responses was linear (P less than 0.01). Plasma B-6 peaked at 0.5 or 1 hour after the PN doses; PLP at 0.5, 1 or 3 hours, depending on size of dose. Plasma B-6 but not PLP approached fasting levels 3 to 5 hours after the 0.5- to 4-mg PN doses; both plasma B-6 and PLP were still elevated 24 hours after 10 mg PN. In general, the rate of urinary B-6 and 4PA excretion was maximal the first 3 hours after the doses. With increasing PN doses, the percent of the dose recovered as urinary B-6 and 4PA decreased from 9 to 7% and 63 to 35%, respectively. Immediately following PL, plasma B-6 and urinary 4PA rose steeply indicating the rapid plasma clearance and oxidation of this B-6 vitamer. Responses to PM were generally slower than for PN or PL, suggesting that PM is absorbed more slowly or metabolized differently, or both, than PL or PN. A dose of at least 1 mg of B-6 is necessary to obtain measurable changes in vitamin B-6 metabolism.

Adult↗
PubMed1980

Bioavailability of vitamin B-6 from wheat bread in humans.

Bioavailability of vitamin B-6 from three types of bread was studied in nine men. Each week one of the three types of bread, whole wheat (WHW), white (W) and W enriched with vitamin B-6 (WB6) was fed (570-600 g/day) to each subject using a Latin square design. The WHW, WB6 and W bread supplied 1.20, 1.18 and 0.35 mg of B-6 daily, respectively. The remaining constant diet supplied 0.38 mg of B-6. When W was fed, the subjects also received an oral dose of pyridoxine to maintain a daily intake of 1.5 mg of vitamin B-6. Dietary, urinary, fecal and blood samples were analyzed for vitamin B-6. The predominant forms of vitamin B-6 in the diet and urine were pyridoxine and pyridoxal, respectively. Fecal vitamin B-6 excretion was significantly higher (P smaller than or equal to 0.01) and urinary 4-pyridoxic acid excretion significantly lower (P smaller than or equal to 0.05) when WHW bread was fed than when either WB6 or W bread was fed. The plasma pyridoxal phosphate level was slightly lower when WHW bread was consumed as compared to when WB6 was fed. There were no significant differences in urinary B-6, plasma B-6 or the activity of the erythrocyte transaminases in relation to the type of bread fed. These data suggest that vitamin B-6 is 5-10% less available from WHW than from WB6 or W bread and an oral dose of B-6. The enrichment of refined wheat flour with pyridoxine is feasible based on the nutritional indices determined in this study.

Adult↗