This investigation was conducted to determine the effect of estrogen replacement therapy (ERT) on vitamin B-6 status of postmenopausal women. Nineteen postmenopausal women served as subjects. Nine (54.7 + 4.7 years) were taking ERT (experimental group); ten (56.8 + 2.3 years) were not (control group). For three consecutive days, subjects recorded their dietary intake and collected their 24-hour urine specimens. On the fourth day, a fasting blood sample was drawn from the subjects. The dietary intake of vitamin B-6, as well as the concentration of total vitamin B-6 in plasma (PB6; and urine (UB6) were measured. PB6 and UB6 were determined by a microbiological method with Saccharomyces uvarum as the assay organism. The mean age, height, hematocrit and hemoglobin values were similar for the two groups. The experimental group was significantly heavier than the control group (p<0.05). The experimental group had a lower mean PB6 than the control group: 47.7 ± 19.7 nmol/L vs. 56.2 + 20.6 nmol/L. These means were not significantly different (p=0.05). PB6 was positively correlated with dietary vitamin B-6 intake (p=0.0001) and vitamin B-6 to protein ratio (p=0.0021). When the means were adjusted for dietary vitamin B-6 and the vitamin B-6 to protein ratio, the mean PB6 of the experimental group (42.7 nmol/L) was significantly lower than that of the control group (60.6 nmol/L) (p<0.05). PB6 was not positively correlated with either age (r=0.20) or the vitamin B-6 dietary history score (r=0.15). UB6 was similar for the two groups. UB6 correlated positively with daily dietary intake of vitamin B-6 (r=0.51, p<0.05) and the ratio of vitamin B-6 to protein (r=0.47, p<0.05), UB6 was not significantly correlated to urine volume (r=0.05). The mean daily intakes of vitamin B-6 and protein were similar for the two groups. One of the 19 subjects had a vitamin B-6 intake that was less than 67 percent of the RDA. Most subjects' (89%) intake of vitamin B-6 was adequate when the ratio of 0.016 mg of vitamin B-6 per g of protein was used as the standard. / Graduation date: 1990

The research presented in this thesis relates to the gastrointestinal control of appetite and some of the consequences of nutritional frailty, namely postprandial hypotension and vitamin D insufficiency. Undernutrition and its consequences are increasingly common problems in an ageing population, and improved management is dependent on an understanding of the factors which are involved in the control of appetite, and the physiological decline of appetite with increasing age termed ‘the anorexia of ageing’. The role of the gastrointestinal hormone ghrelin was specifically evaluated, in relation to the effects of age and nutrient digestion on circulating ghrelin concentrations (Chapters 6 and 7). The effect of fat digestion on the postprandial blood pressure response in healthy older subjects was evaluated in the study reported in Chapter 8. In addition, the results of some intervention studies are described in Chapters 9 and 10, the former study relating to nutritional supplementation as a strategy to increase energy intake, and the latter study to the effects of vitamin D replacement therapy on glucose and insulin metabolism. Whilst plasma ghrelin concentrations are less in older than young rodents, the consequences of healthy ageing on circulating plasma ghrelin concentrations in humans are unclear. The variations in fasting ghrelin concentrations over a sixty year age range were evaluated in healthy young and older subjects (Chapter 6). Plasma ghrelin concentrations were higher in females than males, but did not correlate with age, and were inversely related to body mass index. Ghrelin was independently, and inversely, related to total body skeletal muscle mass, but not to any other body composition variable. Strategies for increasing muscle mass, through resistance exercises, may, accordingly, aid in abolishing the compensatory rise in ghrelin concentrations seen with undernutrition and weight loss. Plasma ghrelin concentrations increase before, and decrease to trough levels within one hour of ingestion of a meal. Macronutrients differ in their ability to suppress ghrelin, being earlier and more pronounced after carbohydrate, and relatively delayed after fat or protein, ingestion. The role of carbohydrate and fat digestion in the suppression of plasma ghrelin concentrations was investigated in healthy young adults (Chapter 7). The suppression of ghrelin concentrations following a sucrose drink was attenuated by acarbose, which slows small intestinal carbohydrate absorption. Ghrelin concentrations were also suppressed after consumption of a fat-enriched drink, however addition of orlistat, which reduces fat digestion and absorption, attenuated the fall in plasma ghrelin. Thus, nutrient digestion is required, in addition to exposure of the small intestine to nutrients, for suppression of ghrelin. Postprandial hypotension describes a significant fall in blood pressure occurring up to two hours after a meal. The magnitude of the fall in postprandial blood pressure depends, in part, on the macronutrient composition of a meal, and the effects are particularly discernable in older adults. Although carbohydrates are particularly potent in reducing postprandial blood pressure in older adults, fat ingestion appears to have comparable, but delayed effects. The role of fat digestion in modifying the blood pressure responses was evaluated in healthy older adults (Chapter 8). There was a fall in blood pressure after ingestion of a high-fat drink. Orlistat, a lipase inhibitor which reduces intestinal fat absorption, potentiated the fall in postprandial blood pressure after a fat-enriched drink. Gastrointestinal function and appetite can be modulated by dietary manipulation of the macronutrient composition of an individual’s diet. The intervention study described in Chapter 9 evaluated the effects of two weeks of dietary fat supplementation on the sensitivity to the satiating effects of intravenous cholecystokinin-8 in healthy older subjects. No differences were observed in fasting, or postprandial plasma cholecystokinin concentrations after the dietary supplementation period compared to regular diet. There were also no differences in spontaneous energy intake at a buffet meal in response to exogenously administered cholecystokinin between the two diet periods. Vitamin D deficiency is common, as is type 2 diabetes, and the two conditions may be linked. There is mounting evidence linking vitamin D deficiency with abnormalities of glucose and insulin metabolism. The effects of vitamin D therapy in healthy young and older adults with low vitamin D concentrations in the setting of normal or impaired glucose tolerance were evaluated (Chapter 10). Vitamin D therapy, which normalised serum 25-hydroxyvitamin D concentrations in these individuals, did not alter glucose or insulin concentrations or insulin sensitivity during an oral glucose tolerance test. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339020 / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2008

Graduation date: 1992

Vitamin B-6 is a vitamin often promoted by the popular press as a cure all. It's role is also being studied in regard to pre-menstrual syndrome, myocardial infarction and alterations in lipid and fatty acid metabolism. This study was designed to investigate whether there was a difference between vitamin B-6 blood levels, during a baseline study, a period of vitamin B-6 depletion and vitamin B-6 supplemention in ten men ages 21-37. The effect of each diet on total cholesterol was also investigated.The experimentally accessible population for this study Laboratory as part of a larger study conducted by Dr. Stephen Coburn of the Fort Wayne State Developmental Center.Analysis of the data indicated:1) A significant difference between red blood cell pyridoxal phosphate and blood plasma levels of vitamin B-6 during the baseline, depletion and supplementation phases in ten men 21-37.2) Total serum cholesterol levels fell significantly through all phases of the study. High density lipoproteins fell significantly during the depletion phase but did not rise significantly during the supplementation phase. Low density lipoproteins showed no significant difference during the three phases of the study. When dietary records were evaluated mean dietary intake during the baseline and supplementation phases of the diet met the Recommended Dietary Allowance (RDA) for vitamin B-6. Mean protein intake also met the RDA with 102.1 grams during the baseline phase and 106.1 grams during the supplementation phase. These intakes are consistent with those found in previous studies conducted by the USDA. Mean intake of fat was lower than the 30 percent of calories recommended by the American Heart Association but wide variation existed among subjects.No physical symptoms of vitamin B-6 deficiency manifested themselves during the study. Subjects reported no other problems associated with low vitamin B-6 intakes.The data indicated that vitamin B-6 intake effects the amount of red blood cell plasma pyridoxal phosphate and plasma vitamin B-6. No clear effect can be found between vitamin B-6 intake and serum cholesterol levels. "Normal" diets also appeared to provide adequate vitamin B-6 to meet both RDA's and somatic needs. Wide variation seems to exist, however, among individuals. / Department of Home Economics

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Massachusetts Amherst, 2008. / Accompanied by .pdf, .jpg and .bmp files. Includes bibliographical references (p. 115-127).

Thesis (M.S.)--University of Massachusetts Amherst, 2008. / Includes bibliographical references (p. 58-62).

Thesis: M.S., Massachusetts Institute of Technology, Department of Nutrition and Food Science, 1980 / Includes bibliographical references. / by Thomas Henry Openshaw. / M.S. / M.S. Massachusetts Institute of Technology, Department of Nutrition and Food Science

The vitamin B-6 status of 11 white adolescent females living in the Blacksburg/Roanoke, Virginia area was evaluated by dietary intakes, coenzyme stimulation of erythrocyte alanine aminotransferase (F-ALAT) activities, and plasma total vitamin B-6 measured microbiologically. Heights and weights of the group were generally within ranges. The vitamin B-6 intakes of the adolescents were 1.47 ± 0.49 mg/day (mean ± SD). Three subjects, or 27.3%, the same subjects classified as inadequate in status by coenzyme stimulation of E-ALAT, were classified as marginal or inadequate in status using ≤ 25 ng/ml total plasma vitamin B-6 levels as the criterion. The plasma pyridoxal, pyridoxine, pyridoxamine and total B-6 vitamer concentrations of subjects having inadequate E-ALAT values were lower, generally significantly, than those of girls with adequate levels. In the subjects with adequate status, the vitamer found in the largest plasma concentration was pyridoxine. A significant correlation (r = 0.82, p < 0.01) was observed between total plasma vitamin B-6 levels determined microbiologically and coenzyme stimulation values. / Master of Science

The influence of vitamin B-6 intake on vitamin B-6 status and the concentration of B-6 vitamers in milk of 21 white lactating women (21 to 35 years) was examined at 3 to 7 months postpartum. None of the women met the RDA for lactating women of 2.5 mg/day when considering vitamin B-6 intakes from food sources alone. All subjects taking vitamin B-6 supplements had adequate vitamin B-6 status as determined by coenzyme stimulation of erythrocyte alanine aminotransferase activity; all subjects not taking vitamin B-6 supplements had inadequate vitamin B-6 status. Plasma pyridoxal 5-phosphate values were significantly higher for subjects in the supplemented than in the nonsupplemented group. Pyridoxal, pyridoxamine, pyridoxine, and total vitamin B-6 concentrations in milk were higher, sometimes significantly, in the supplemented than in the unsupplemented group as determined by microbiological assay and HPLC. There were significant correlations between data obtained by the microbiological and HPLC analyses for pyridoxal and total vitamin B-6 concentrations. Pyridoxal was the predominant B-6 vitamer found in human milk. Distribution of the B-6 vitamers appeared to stay relatively constant despite vitamin B-6 status. / Master of Science