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OBJECTIVE--We sought to assess the intra- and interindividual variability of glycemic index value determinations for white bread using glucose as the reference food. RESEARCH DESIGN AND METHODS--A total of 23 [...]

Background: The magnitude of the effect of soy protein on lipoprotein concentrations is variable. This discordance is likely attributable to the various forms of soy protein used and to unrecognized shifts in dietary fatty acid, cholesterol, and fiber. Objective: The objective was to evaluate the effect of soybean processing as well as soy consumption relative to animal protein, independent of alterations in major dietary variables, on cardiovascular disease risk factors and vascular endothelial function. Design: Twenty-eight hypercholesterolemic subjects (LDL cholesterol [greater than or equal to] 3.36 mmol/L) aged >50 y consumed each of 4 diets for 6-wk periods according to a randomized crossover design. The diets [55% of energy as carbohydrate, 30% of energy as fat, and 15% of energy as protein--7.5% of energy as experimental protein (37.5 g/d)] were designed to contain products made from either whole soybeans, soyflour, or soymilk and were compared with a diet containing an equivalent amount of animal protein (meat, chicken, and dairy products). The cholesterol, fiber, and fatty acid profiles of the diets were equalized. All food and drink were provided, and body weight was maintained throughout the study. Results: No significant differences in blood pressure, vascular endothelial function, or total cholesterol, VLDL-cholesterol, triacylglycerol, apolipoprotein B, or C-reactive protein concentrations were observed between the diets. Consumption of the soymilk diet resulted in a modest decrease (4%) in LDL-cholesterol concentrations compared with the animal-protein and soyflour diets (P < 0.05) and higher HDL-cholesterol (1%) and apolipoprotein A-I (2%) concentrations compared with the soybean and soyflour diets (P < 0.05). Conclusions: The results suggest that the consumption of differently processed soy-based products and different types of protein (animal and soy) has little clinical effect on cardiovascular disease risk factors, including peripheral endothelial function, when other major dietary variables are held constant. KEY WORDS Soy protein, lipids, lipoproteins, apolipoproteins, cholesterol, endothelial function

Background: A variety of soybean oils were developed with improved oxidative stability and functional characteristics for use as alternatives to partially hydrogenated fat. Objective: The objective was to assess the effect of selectively bred and genetically modified soybean oils with altered fatty acid profiles, relative to common soybean and partially hydrogenated soybean oils, on cardiovascular disease risk factors. Design: Thirty subjects (16 women and 14 men) aged >50 y with LDL-cholesterol concentrations >130 mg/dL at screening consumed 5 experimental diets in random order for 35 d each. Diets contained the same foods and provided 30% of energy as fat, of which two-thirds was either soybean oil (SO), low-saturated fatty acid soybean oil (LoSFA-SO), high-oleic acid soybean oil (HiOleic-SO), low--[alpha]-linolenic acid soybean oil (LoALA-SO), or partially hydrogenated soybean oil (Hydrog-SO). Results: Plasma phospholipid patterns reflected the predominant fat in the diet. LDL-cholesterol concentrations were 3.66 [+ or -] [0.67.sup.b], 3.53 [+ or -] [0.77.sup.b], 3.70 [+ or -] [0.66.sup.b], 3.71 [+ or -] [0.64.sup.a,b], and 3.92 [+ or -] [0.70.sup.a] mol/L; HDL-cholesterol concentrations were 1.32 [+ or -] [0.32.sup.a,b], 1.32 [+ or -] [0.35.sup.b,] 1.36 [+ or -] [0.33.sup.a], 1.32 [+ or -] [0.33.sup.b], and 1.32 [+ or -] [0.32.sup.a,b] mol/L for the SO, LoSFA-SO, HiOleic-SO, LoALA-SO, and Hydrog-SO diets, respectively (values with different superscript letters are significantly different, P < 0.05). No significant effects were observed on VLDL-cholesterol, triacylglycerol, lipoprotein(a), and C-reactive protein concentrations or on ratios of LDL cholesterol to apolipoprotein B (apo B) and HDL cholesterol to apo A-I. Total cholesterol:HDL cholesterol was lower after subjects consumed the unhydrogenated soybean oils than after they consumed the Hydrog-SO diet. Conclusions: All varieties of soybean oils resulted in more favorable lipoprotein profiles than did the partially hydrogenated form. These soybean oils may provide a viable option for reformulation of products to reduce the content of trans fatty acids. KEY WORDS Soybean oils, selective breeding, genetic modification, cardiovascular disease, CVD risk factors, trans fatty acids, LDL cholesterol, HDL cholesterol, triacylglycerol, C-reactive protein, fatty acids

Background: Partially hydrogenated fat has an unfavorable effect on cardiovascular disease risk. Palm oil is a potential substitute because of favorable physical characteristics. Objective: We assessed the effect of palm oil on lipoprotein profiles compared with the effects of both partially hydrogenated fat and oils high in monounsaturated or polyunsaturated fatty acids. Design: Fifteen volunteers aged [greater than or equal to]50 y with LDL cholesterol [greater than or equal to] 130 mg/dL were provided with food for each of 4 diets (35 d/phase) varying in type of fat (partially hydrogenated soybean, soybean, palm, or canola; two-thirds fat, 20% of energy). Plasma fatty acid profiles, lipids, lipoproteins, apolipoprotein A-I, apolipoprotein B, lipoprotein(a), glucose, insulin, HDL subfractions, and indicators of lipoprotein metabolism (HDL-cholesterol fractional esterification rate, cholesteryl ester transfer protein, phospholipid transfer protein, and paraoxonase activities) were measured at the end of each phase. Results: Plasma fatty acid profiles reflected the main source of dietary fat. Partially hydrogenated soybean and palm oils resulted in higher LDL-cholesterol concentrations than did soybean (12% and 14%, respectively; P < 0.05) and canola (16% and 18%; P < 0.05) oils. Apolipoprotein B (P < 0.05) and A-I (P < 0.05) concentrations mirrored the pattern of LDL- and HDL-cholesterol concentrations, respectively. No significant effect on the total-to-HDL cholesterol ratio was observed for palm oil compared with the other dietary fats. HDL3 cholesterol was higher after palm oil than after partially hydrogenated and soybean oils (P < 0.05). Differences in measures of glucose and HDL intravascular processing attributable to dietary fat were small. Conclusion: Palm and partially hydrogenated soybean oils, compared with soybean and canola oils, adversely altered the lipoprotein profile in moderately hyperlipidemic subjects without significantly affecting HDL intravascular processing markers. KEY WORDS Cardiovascular disease, trans fatty acids, lipoproteins, palm oil, partially hydrogenated soybean oil, LDL cholesterol, HDL cholesterol, insulin, glucose, cholesteryl ester transfer protein, phospholipid transfer protein

Background: Several clinical trials have suggested that soy intake decreases oxidative stress. Soy isoflavones have antioxidant properties in vitro, but results of supplementation in clinical trials are inconclusive. Objective: The objective was to evaluate the independent effects of soy protein and soy-derived isoflavones on plasma antioxidant capacity and biomarkers of oxidative stress. Design: Forty-two hypercholesterolemic (LDL cholesterol > 3.36 mmol/L) subjects aged >50 y were provided with each of 4 diets in random order in a crossover design. Diets varied in protein source (10% of energy, soy or animal) and isoflavone content (trace or 50 mg/1000 kcal) and were consumed for 42 d each. Plasma antioxidants, protein carbonyls, malondialdehyde, total antioxidant performance, LDL oxidizability, and urinary [F.sub.2]-isoprostanes were measured at the end of each dietary phase. Results: Plasma antioxidant concentrations were not significantly different, regardless of dietary treatment, except for isoflavones, which were higher after isoflavone supplementation (P = 0.0001). Although plasma total antioxidant performance was 10% higher with soy protein intake, regardless of dietary isoflavones (P = 0.0003), soy protein did not significantly affect most individual markers of oxidative stress (LDL oxidizability, urinary [F.sub.2]-isoprostanes, malondialdehyde, or protein carbonyls in native plasma). However, soy protein was associated with modestly lower concentrations of protein carbonyls in oxidized plasma. There was no significant effect of isoflavones on LDL oxidation, urinary F2isoprostanes, or protein carbonyl groups, although, paradoxically, the plasma malondialdehyde concentration was significantly higher after the isoflavone-rich diets (P = 0.04). Conclusions: Diets relatively high in soy protein or soy-derived isoflavones have little effect on plasma antioxidant capacity and biomarkers of oxidative stress. Am J Clin Nutr 2005;81:43-9. KEY WORDS Animal protein, antioxidants, antioxidant capacity, cardiovascular disease, isoflavones, oxidative stress, soy protein

Background: Dietary trans fatty acids (FAs), which are formed during the process of hydrogenating vegetable oil, are known to increase plasma LDL-cholesterol concentrations. However, their effect on LDL particle size has yet to be investigated. Objective: We investigated the effect of trans FA consumption on the electrophoretic characteristics of LDL particles. Design: Eighteen women and 18 men each consumed 5 experimental diets in random order for 35-d periods. Fat represented 30% of total energy intake in each diet, with two-thirds of the fat in the form of semiliquid margarine (0.6 g trans FAs/100 g fat), soft margarine (9.4 g trans FAs/100 g fat), shortening (13.6 g trans FAs/100 g fat), stick margarine (26.1 g trans FAs/100 g fat), or butter, which was low in trans FAs (2.6 g trans FAs/100 g fat) but rich in saturated fat. LDL particle size and distribution were characterized by nondenaturing, 2-16% polyacrylamide gradient gel electrophoresis. Results: Relative to the LDL particle size observed after consumption of the butter-enriched diet, LDL particle size decreased significantly and in a dose-dependent fashion with increasing amounts of dietary trans FAs (P < 0.001). Cholesterol concentrations in large (> 260 [Angstrom]) and medium-sized (255-260 [Angstrom]) LDL particles also increased proportionately to the amount of trans FAs in the diet. Conclusion: Consumption of dietary trans FAs is associated with a deleterious increase in small, dense LDL, which further reinforces the importance of promoting diets low in trans FAs to favorably affect the lipoprotein profile. KEY WORDS trans Fatty acids, hydrogenated fat, LDL particle size, diet, cholesterol

The effects of National Cholesterol Education Program (NCEP) Step 2 diets on plasma lipoprotein profiles in men [mean ([+ or -] SD) age: 44 [+ or -] 15 y, range: 19-81 y] and 48 women (mean age: 50 [+ or -] 21 y, range: 19-81 y) participating in five previously published studies were examined. Subjects were placed on a baseline diet similar to an average American diet (35-41% total fat, 13-16% saturated fat, 31-45 mg cholesterol/MJ) and then on an NCEP Step 2 diet (18-29% total fat, 4-7% saturated fat, 11-20 mg cholesterol/MJ) under isoenergetic conditions. All food and drink were provided. Compared with the baseline diet, consumption of the NCEP Step 2 diets was associated with significant decreases in concentrations of low-density-lipoprotein (LDL) cholesterol (-18.9% and - 15.6%, respectively) and high-density-lipoprotein (HDL) cholesterol (-17.0% and -11.2%, respectively) in both men and women. Men with the apolipoprotein (apo) E 3,4 phenotype had a significantly greater decrease in LDL cholesterol (-24.2%) with the NCEP Step 2 diets than men with the apo E 3,3 phenotype (-17.7%). Men with the apo A-IV 1,2 phenotype tended to have less LDL cholesterol lowering (-12.8%) than men with the apo A-IV 1,1 phenotype (-19.6%), but this difference was not significant. No differences were seen by apo E and A-IV phenotype in women. A large variability in lipid response to the diet was observed, with changes in LDL cholesterol ranging from +3% to -55% in men and and from +13% to -39% in women. Forty-eight percent of the variability in LDL-cholesterol response (in mmol/L) to the diet could be accounted for by baseline LDL concentrations and age in men, and 13% by age in women.

Regression analysis of the combined published data on the effects of dietary fatty acids and cholesterol on serum cholesterol and lipoprotein cholesterol evaluated with groups of human subjects shows that 1) saturated fatty acids increase and are the primary determinants of serum cholesterol, 2) polyunsaturated fatty acids actively lower serum cholesterol, 3) monounsaturated fatty acids have no independent effect on serum cholesterol and, 4) dietary cholesterol increases serum cholesterol and must be considered when the effects of fatty acids are evaluated. More limited data on low-density-lipoprotein cholesterol (LDL-C) show that changes in LDL-C roughly parallel the changes in serum cholesterol but that changes in high-density-lipoprotein cholesterol cannot be satisfactorily predicted from available data.

As a growing number of fast food and chain restaurants display the calorie content of their dishes on websites and menus, a study suggests some of this information may be [...]

Folate (folic acid) is a water-soluble B-vitamin especially important for growth and reproduction. Pregnant and lactating monkeys and their infants were studied to assess the effects of marginal (mild) folate deficiency. The monkeys were found to be an excellent model for human pregnancy and folate deficiency. The consequences of even marginal folate deficiency are serious during pregnancy. Premature delivery, stillbirth, miscarriage, low birth weight and birth defects have all been linked to maternal folate deficiency. It was found that both the monkey fetus and nursing infant were directly affected by the mother's deficiency. The baby monkey did not have preferential access to the mother's folate stores, as occurs with some nutrients. Instead, poor maternal folate status appeared to cause the same condition in the infant. Marginal folate deficiency can progress to megaloblastic anemia, a more severe stage. Megaloblastic anemia is a blood condition characterized by the presence of large, abnormal red corpuscles (megaloblasts). While megaloblastic anemia is relatively uncommon in the US, marginal deficiency during pregnancy and lactation is fairly common. This study shows that even mild folate deficiency has adverse consequences for the developing infant monkey.

Several types of malnutrition have been described, based on the nutrient that is most inadequate in the diet. Protein deficiency and calorie (energy) deficiency may occur independent of each other, or in combination. Malnutrition primarily due to protein deficiency is known as kwashiorkor; energy deficiency is usually called marasmus. The symptoms of and treatments for protein versus calorie malnutrition are different. Infant squirrel monkeys were chosen as experimental subjects because their growth and metabolism are similar to human infants. Monkeys were fed either a low-protein diet, a low-calorie diet, or a low-protein and low-calorie diet. All restrictions were severe enough to prevent any growth at a stage when growth is normally rapid. Monkeys fed the low-protein diet became inefficient at using calories, wasting some of the energy in their diet. Restricting protein appeared to raise the animal's energy needs. However, restricting calories did not raise protein needs in this study, which contradicts previous research. This has application to human populations during famine. It is concluded that when total food (calorie) intake is limited, protein needs do not rise. If additional protein foods were needed during starvation, they could not be obtained and the individuals would not survive. Foods high in protein are generally less available than other foods in a malnourished community.