ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718605

出版商:Routledge    

年代:1996

数据来源: Taylor

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718606

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

Trans fatty acids (t-FA) are geometrical isomers of unsaturated fatty acids that assume a saturated fatty acid-like configuration. Human diets contain t-FA derived from animal sources (e.g., dairy products and ruminant meats), but most are supplied by products containing industrially hydrogenated vegetable oils (e.g., margarines, shortenings and baked goods). Typical intake of t-FA in American diets has been estimated to be between 8-15 g/day, although wide variation exists between individuals. Human clinical studies since 1990 have revealed that relative to cis-monounsaturated fatty acids (i.e., oleic acid), t-FA increase total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), and tend to decrease high density lipoprotein cholesterol (HDL-C) concentrations. Additionally, t-FA tend to increase the atherogenic lipoprotein (a). Thus, t-FA induce an adverse plasma lipid profile (increased ratios of TC/LDL-C and LDL-C/HDL-C), which represents increased risk for coronary heart disease. The effects of t-FA on LDL-C and HDL-C appear to be directly related to intake and clinically measurable above 3%en as t-FA. The cholesterol-raising ability of t-FA is analogous to that of the 12-16 carbon saturated fatty acids, possibly reflecting increased LDL production or delayed LDL clearance. By contrast, t-FA are unlike the saturated fatty acids in their depression of HDL-C. Preliminary evidence suggests that at least part of their impact on lipoproteins reflects increased serum cholesteryl ester transfer protein activity, i.e., increased transfer of cholesteryl esters from HDL to LDL. Since the adverse effects of t-FA on human plasma lipids may be confined to specific isomers, future studies delineating their effects are warranted.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718607

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

Zinc is an essential nutrients and plays an important role in growth and sexual function. Zinc deficiency has been known to cause growth retardation and hypogonadism. Several mechanisms of growth retardation and hypogonadism due to zinc deficiency have been suggested. Zinc affects growth hormone (GH) metabolism. Conversely, GH affects zinc metabolism. Zinc deficiency may result in reduced GH production and/or insulin-like growth factor-I (IGF-I). Zinc deficiency may also affect bone metabolism and gonadal function. The interrelationships among zinc, growth, gonadal function, and GH-IGF-I axis appears to be complex.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718608

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

Endothelial cells interact with blood components and the abluminal tissues, thus playing an active role in many aspects of vascular function. Numerous physiologic and pathophysiologic stimuli are often mediated by nutrients that can contribute to the overall functions of endothelial cells in the regulation of vascular tone, coagulation, cellular growth, immune and inflammatory responses. Therefore, nutrient-mediated functional changes of the endothelium and the underlying tissues may be significantly involved in disease processes such as atherosclerosis. There is evidence that individual nutrients or nutrient derivatives may either provoke or prevent metabolic and physiologic perturbations of the vascular endothelium. Diets high in fat and/or calories are considered a risk factor for the development of atherosclerosis. Our research has shown that certain diet-derived lipids and their derivatives can disrupt normal endothelial integrity, thus reducing the ability of the endothelium to act as a selectively permeable barrier to blood components. Mechanisms underlying fatty acid-mediated endothelial cell dysfunction may be related to changes in fatty acid composition as well as to an increase in cellular oxidative stress. Selective lipid accumulation and fatty acid changes in endothelial cells can modulate membrane fluidity, proteoglycan metabolism and signal transduction mechanisms. Most importantly, dietary fats rich in certain unsaturated fatty acids, may be atherogenic by enhancing the formation of reactive oxygen intermediates. A subsequent imbalance in cellular oxidative stress/antioxidant status can activate oxidative stress-responsive transcription factors, which in turn may promote cytokine production, expression of adhesion molecules on the surface of endothelial cells, and thus intensify an inflammatory response in atherosclerosis. Our data also suggest that certain nutrients, which have antioxidant and/or membrane stabilizing properties, can protect endothelial cells by interfering with lipid/cytokine-mediated endothelial cell dysfunction. These findings contribute to the understanding of the interactive role of dietary fats with inflammatory components, as well as with nutrients that exhibit antiatherogenic properties, in the development of atherosclerosis.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718609

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

We investigated zinc (Zn) status and effect of Zn supplementation in relation to iron deficiency anemia in Japanese female endurance runners in an attempt to define the role of Zn in hematologic abnormalities.After estimating zinc status based on total body zinc clearance (ClZn), 21 women runners were divided into two groups: one group was of normal Zn status (group A), and the other was a Zn deficient group (group B). We then compared the hematological status in both groups, before and after iron or iron plus Zn supplementation.Number of red blood cells (RBC), serum concentrations of hemoglobin (Hb), iron and total protein in Group A were significantly higher than those in Group B, while serum Zn levels were similar in both groups. There was a significantly positive correlation between ClZn and total protein, and hemoglobin in all subjects. After combined treatment with ferrous citrate and zinc sulfate, the concentrations of total protein, iron, RBC, and Hb were significantly increased in the four Zn deficient runners.Zn status to some extent can account for hematological abnormalities in female endurance runners.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718610

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

An elevated serum concentration of the metabolite, homocysteine (Hcys): 1) can indicate folate or vitamin B12 deficiency, 2) is an independent risk factor for vascular disease. The metabolite, methylmalonic acid (MMA), is elevated in deficiency of vitamin B12, but not folate. The purpose of this study was to determine the effect of self-selected vitamin supplementation and other variables on serum Hcys and MMA concentrations in elderly men and women.Serum concentrations of Hcys, MMA, folate and vitamin B12 were measured for elderly volunteers, age 68-96 years, and compared for those consuming (26 men, 25 women) and not consuming (24 men, 25 women) self-selected vitamin supplements.Compared with the nonsupplemented group, the supplemented group had lower mean serum MMA (208 +/−162 vs. 241 +/−98 nmol/L [+/−SD]) and Hcys (9.5 +/−2.6 vs. 11.2 +/−2.7 mumol/L); and higher serum vitamin B12 (391 +/−174 vs 292 +/−107 pmol/L), and serum folate (46 +/−15 vs. 24 +/−10 nmol/L) p<0.05. Among all 100 subjects, the prevalence of serum vitamin B1216.2 mumol/L, 3; folate<5.0 nmol/L, none. Based on serum vitamin B12<221 nmol/L with elevated serum MMA, vitamin B12 deficiency was probable in seven subjects, of whom two were supplemented. All three subjects with elevated serum Hcys had elevated serum MMA as well, suggesting vitamin B12 deficiency or renal insufficiency. A stepwise linear regression model for serum Hcys explained 61.7% of the variance, and included (in order) serum creatinine, folate, vitamin B12, albumin, age and body mass index (BMI). A model with serum MMA replacing serum vitamin B12 explained 64.1% of the variance in serum Hcys. Folate did not enter the model for supplemented subjects, supporting a“threshold effect”: serum Hcys was inversely related to serum folate at lower serum folate (nonsupplemented subjects), but at higher serum folate (supplemented subjects), the relationship was flat. In supplemented subjects, serum Hcys was still related to vitamin B12 status, confirming that tissue deficiency of the vitamin was present.Results showed potential usefulness of serum MMA and Hcys in identifying subclinical or tissue deficiency of vitamin B12. Clinicians should be aware of the risk of vitamin B12 deficiency in older people and of current screening algorithms using serum metabolites. These elderly volunteers had generally good folate status; nevertheless, some subjects seemed likely to benefit from an improvement in folate status that would reduce their serum Hcys within the normal range. The role of serum creatinine in the normal range in predicting serum Hcys, a vascular disease risk factor, remains unexplained.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718611

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

To assess whether the addition of gum arabic (GA) to oral rehydration solutions (ORS) of either 60 or 90 mM sodium enhances net water and sodium absorption in rats.Perfusion of a jejunal segment of male juvenile rats under anesthesia, and determination of net water and sodium absorption, and unidirectional fluid movements using appropriate markers.Addition of 5 and 10 g/L of GA increased the rates of sodium removal from the intestinal lumen perfused with ORS containing either 60 or 90 mM sodium. Net water absorption was unaffected, although GA tended to facilitate bidirectional fluid movement. The alteration of solute transport rates by the addition of 10 g/L GA was associated with an expansion of the basolateral intercellular spaces.A soluble fiber such as GA appears to be an effective enhancer of sodium absorption from ORS when tested in experimental animals. Since GA does not affect viscosity, an alteration of solute diffusibility through the brush border membrane and changes in intercellular compartments may underlie the observed improvement of sodium absorption.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718612

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

We conducted a prospective randomized, single-blinded clinical trial to test the hypothesis that intake of formula plus cereals between the ages of 16 and 26 weeks postnatally (as compared to formula alone) would lead to lower bone mineral content (BMC), higher parathyroid hormone (PTH) concentration, lower serum calcium (Ca), magnesium (Mg) and osteocalcin (OC); and increased continuous night sleep.At 16 weeks postnatally, 41 healthy, term infants were randomized to formula alone or formula and cereal.We found no significant differences in growth or sleep pattern, nor in BMC between groups. Serum PTH concentration was significantly increased in the cereal group at 26 weeks.We speculate that the increase in PTH is due to relative Ca deficiency or is responsive to increased phosphate load in the cereal group.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718613

出版商:Routledge    

年代:1996

数据来源: Taylor

摘要:

To evaluate the effects of two levels of total dietary fiber (10 g vs. 20 g) and two soluble:insoluble fiber ratios (1:4 vs. 2:3) on postprandial glucose and lipid metabolism in hypertriglyceridemic subjects with non-insulin-dependent diabetes mellitus (NIDDM).Eight NIDDM, mildly hypertriglyceridemic subjects consumed four test breakfasts, each containing variable proportions of the same cereal and fruit fiber sources. Blood samples were obtained during the 4 hours following the test meals and analyzed for glucose, insulin, triglyceride, total cholesterol and high density lipoprotein cholesterol.The incremental area under the curve for glucose and insulin was lowered after consuming 20 g as compared to 10 g of dietary fiber (p<0.05), but was not affected by the soluble insoluble fiber ratio. The postprandial lipemia was similar after all test meals.The proportion of soluble to insoluble fiber in cereal and fruit does not necessarily predict the effect of fiber on the glycemic response, while the overall quantity of fiber does appear to affect postprandial glucose metabolism in NIDDM.

ISSN:0731-5724    

DOI:10.1080/07315724.1996.10718614

出版商:Routledge    

年代:1996

数据来源: Taylor