The Journal of nutrition
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The Journal of nutrition · Apr 2000
ReviewPituitary hormone secretion in normal male humans: acute responses to a large, oral dose of monosodium glutamate.
Numerous studies have shown that the administration of a glutamate receptor agonist or a high dose of glutamate stimulates pituitary hormone secretion in animals. However, only a single human study has reported that an oral load of glutamic acid induced the secretion of prolactin and probably adrenocorticotropic hormone (ACTH) (but not other pituitary hormones). Because of glutamate's use in foods as monosodium glutamate (MSG), a flavoring agent, and the limited amount of human data, we studied the effect of a large oral dose of MSG in humans on the secretion of prolactin and other pituitary hormones. ⋯ Ingestion of MSG raised plasma glutamate concentrations 11-fold; the protein meal did not raise plasma glutamate. The results demonstrate that MSG ingestion in humans does not modify anterior pituitary hormone secretion. One implication is that diet-derived glutamate may not penetrate into hypothalamic regions controlling anterior pituitary function.
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The Journal of nutrition · Mar 2000
In vitro fermentation of swine ileal digesta containing oat bran dietary fiber by rat cecal inocula adapted to the test fiber increases propionate production but fermentation of wheat bran ileal digesta does not produce more butyrate.
This experiment evaluated three hypotheses: i) production of propionate is increased during fermentation of substrate containing oat bran (OB)(6); ii) production of butyrate is increased during fermentation of substrate containing wheat bran (WB) and iii) results of in vitro fermentations using physiological substrates and inocula agree with in vivo data. Ileal digesta collected from swine fed OB and WB were the substrates. Digesta was fermented for 0-96 h in an anaerobic in vitro system using inocula prepared from ceca of rats fed the same fiber sources. ⋯ OB digesta fermentation produced a significantly greater (P < 0.05) molar proportion of SCFA as propionate. Bacterial mass increased more and was maintained longer during fermentation of OB digesta than the WB digesta. Our results indicate that dilution of undigested WB fiber and not n-butyrate production is one mechanism by which WB may protect colonic mucosa; propionate production is increased during fermentation of beta-glucan in OB; and an in vitro system using physiological sources of inoculum and substrate containing WB and OB yields results that agree with in vivo findings in humans and rats.
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The Journal of nutrition · Feb 2000
ReviewDietary fat intake and regulation of energy balance: implications for obesity.
Obesity represents a major threat to health and quality of life. Although obesity has strong genetic determinants, the increasing prevalence of obesity in populations around the world suggests that environmental factors are promoting or exacerbating the problem. Experts are calling for public health efforts to deal with the global epidemic of obesity. ⋯ In this paper, we review evidence from animal studies, carefully controlled laboratory studies, cross-sectional studies, clinical trials and studies in individuals at high risk to develop obesity. Although there are many environmental factors promoting excess energy intake and discouraging energy expenditure, it is clear that consumption of a high fat diet increases the likelihood of obesity and that the risk of obesity is low in individuals consuming low fat diets. On the basis of the available data, the current public health recommendations to lower dietary fat intake appear to be appropriate.
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The Journal of nutrition · Oct 1999
Oral administration of a glutamine-enriched diet before or after endotoxin challenge in aged rats has limited effects.
Numerous studies indicate beneficial effects of glutamine (Gln) in many models of catabolic adult rats. No data were available for aged rats. The effects of oral L-Gln-enriched diet were tested in endotoxemic 24-mo old rats. ⋯ In a second study, after endotoxin challenge, healthy 24-mo-old rats were then food-deprived for 2 d (from d0 to d2), received a nonpurified diet for 4 d (from d2 to d6), and then Cas or L-Gln-supplemented diet for 7 d (from d6 to d13). No beneficial effects of Gln supplementation were observed except an increase of 50 and 56% in sucrase and glucoamylase activities in the ileum of Gln-treated rats, (P
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The Journal of nutrition · May 1999
Calcium intake is weakly but consistently negatively associated with iron status in girls and women in six European countries.
Several studies indicate that intake of calcium can inhibit iron absorption especially when taken simultaneously. In the CALEUR study, a cross-sectional study among girls (mean 13.5 y) and young women (mean 22.0 y) in six European countries, the association between calcium intake and iron status was studied. In 1,080 girls and 524 women, detailed information on calcium intake was collected by means of a 3-d food record, and serum ferritin, serum iron, serum transferrin and transferrin saturation were measured as indicators of iron status. ⋯ Only in girls, transferrin saturation as a measure for short-term iron status was inversely associated with calcium intake (adjusted overall coefficient -0.18 +/- 0.08). However, analysis per country separately showed no consistency. We conclude that dietary calcium intake is weakly inversely associated with blood iron status, irrespective of whether calcium was ingested simultaneously with iron.