Impact of nondigestible carbohydrates on serum lipoproteins and risk for cardiovascular disease

Digestion-resistant fraction from soybean [Glycine max (L.) Merrill] induces hepatic LDL receptor and CYP7A1 expression in apolipoprotein E-deficient mice

Soybean [Glycine max (L.) Merrill] is known to have hypocholesterolemic effects; however, the function and mechanism of its digestion-resistant fraction (RF) in cholesterol reduction is not clearly understood. In the present study, we investigated the hypocholesterolemic effects of the RF from soybean in C57BL/6J and apolipoprotein E (apoE)-deficient mice. RFs were prepared either from raw or preheated crops to measure compositional changes in RF during cooking. Preheating reduced the RF yields and the resistant starch (RS) fraction in RF. After 1 week of feeding, the raw soybean RF (5%, w/w) was the most effective in lowering plasma cholesterol concentrations by 27% (P<.05) in apoE-deficient (apoE-/-) mice. A smaller but significant reduction was found in C57BL/6J mice. The RF from preheated soybean tended to have lower hypocholesterolemic effects than did the RF from raw soybean in apoE-/- mice. This suggests the RS may be a key hypocholesterolemic component from soybean RF. RF consumption (5%, w/w) dramatically increased hepatic low-density lipoprotein receptor and cholesterol 7alpha-hydroxylase expression in both apoE-/- and C57BL/6J mice followed by increased bile acid excretion. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase was only marginally altered. Our results show that the RF, especially from raw soybean containing high level of RS, significantly reduces plasma cholesterol concentrations under hyperlipidemic condition. The cholesterol was reduced by multiple mechanisms such as increased hepatic cholesterol uptake, cholesterol degradation into bile acids and bile acid excretion.

Cardiovascular Disease Risk Reduction in Older Adults

Preventing cardiovascular events in older persons presents unique challenges to clinicians. Cardiovascular disease accounts for a large amount of disability and mortality in older persons. Older persons are often faced with unique and multiple challenges to health, including cognitive decline, social isolation, financial constraints, and physical disabilities. As more and more older persons are enrolled in studies that aim to better understand coronary heart disease and its prevention, new information is becoming available that allow clinicians to improve outcomes in the older adult. The most recent updates in the area of medical management, as well as updates of recommendations for lifestyle changes, including physical activity and dietary recommendations for older persons at risk, are presented in this article.

L-rhamnose and lactulose decrease serum triacylglycerols and their rates of synthesis, but do not affect serum cholesterol concentrations in men

Colonic short-chain fatty acids (SCFA) may affect hepatic lipid metabolism. Lactulose increases colonic acetate production, whereas L-rhamnose increases propionate. To test the effects of oral L-rhamnose and lactulose for 28 d on fasting concentrations and hepatic synthesis of lipids in humans, 18 men were administered 25 g/d of L-rhamnose, lactulose, or d-glucose for 4 wk in a partially randomized crossover design, with blood collected from fasting subjects on the first and last day of each period. Cholesterol and triacylglycerol (TG) synthesis rates were determined using deuterated water uptake rate over the last 24 h of each period. Postprandial blood lipids, and glucose and insulin were assessed in 11 subjects on d 28. Fasting serum cholesterol was unchanged; however, when expressed as a percentage change, TG were decreased, relative to baseline (P < 0.04), by L-rhamnose (-10%) and lactulose (-10%), compared with D-glucose, which increased serum TG (+11%). Net TG-fatty acid (TGFA) synthesis on d 28 was lower with L-rhamnose (2.42 +/- 0.38 g/d) and lactulose (2.62 +/- 0.35 g/d) than with D-glucose (2.96 +/- 0.31 g/d, P < 0.01). We conclude that these results do not support a primary role for propionate in the cholesterol-lowering effect of soluble fiber. However, both lactulose and L-rhamnose lowered serum TG (expressed as a percentage change) and TGFA synthesis, compared with d-glucose, which increased them. Although these data are consistent with inhibition of TGFA synthesis by SCFA, other aspects of the metabolism of these sugars cannot be ruled out as putative agents of their TG-lowering effects.

Grain legume proteins and nutraceutical properties

Grain legumes are a valuable source of food proteins. Their exploitation is expected to grow in relation of a growing world's food needs. Moreover, it is currently taking place a reappraisal of the beneficial effects of legume seed dietary intake, which are the basis for various health claims. Proteins and peptides concur to the observed biological activities of legume seeds, but their effect(s) has(ve) not completely been disclosed. Aims of this review are: to report the most relevant putative positive effects of grain legumes on human health and to give an account of the current knowledge on the demonstrated legume seed protein biological activities. Specific effects on the prevention and treatment of various diseases, mostly of which are typical of the affluent countries, are reported. Examples of studies at molecular level aimed at elucidating of the underlying mechanism(s) are given. The prospects on targeted legume protein exploitation in the nutraceutical area, including the biotechnological approaches, are also considered.

Whole-grain intake and the prevalence of hypertriglyceridemic waist phenotype in Tehranian adults

BACKGROUND

Although dietary guidelines recommend increased intake of grain products to prevent chronic diseases, no epidemiologic data associate whole-grain intake with hypertriglyceridemic waist (HW) phenotype.

OBJECTIVE

We aimed to evaluate the relation between whole-grain intakes and the prevalence of HW phenotype in adults in Tehran, Iran.

DESIGN

Whole-grain intake, serum triacylglycerol concentration, and waist circumference (WC) were assessed in a population-based, cross-sectional study of 827 Iranian subjects (357 men and 470 women) aged 18-74 y. HW phenotype was defined as serum triacylglycerol concentrations > or =150 mg/dL and concurrent WC > or = 80 cm (men) and > or =79 cm (women).

RESULTS

Mean (+/-SD) consumption of whole and refined grains was 93 +/- 29 and 201 +/- 57 g/d, respectively. Subjects in the highest quartile of whole-grain intake had a significantly lower prevalence of HW (29%) than did those in the lowest quartile (44%; P < 0.05). Conversely, those in the highest quartile of refined-grain intake had a significantly higher prevalence of HW (45%) than did those in the lowest quartile (27%; P < 0.05). After control for potential confounding factors, a significantly decreasing trend was observed for the risk of HW phenotype across quartiles of whole-grain intake (odds ratios among quartiles: 1.00, 0.95, 0.90, and 0.78, respectively; P for trend = 0.02). Higher consumption of refined grains was associated with better odds of HW phenotype (by quartile: 1.00, 1.38, 1.65, and 2.1; P for trend = 0.01).

CONCLUSION

Whole-grain intake is inversely and refined-grain intake is positively associated with the risk of HW.

Health effect of vegetable-based diet: lettuce consumption improves cholesterol metabolism and antioxidant status in the rat

BACKGROUND & AIMS

It is often assumed that fruits and vegetables contribute to protect against degenerative pathologies such as cardiovascular diseases. Besides epidemiological observations, scientific evidences for their mechanism of action are scarce. In the present study, we investigated the mean term and post-prandial effects of lettuce ingestion on lipid metabolism and antioxidant protection in the rat.

RESULTS

Feeding rats a 20% lettuce diet for 3 weeks resulted in a decrease cholesterol LDL/HDL ratio and a marked decrease of liver cholesterol levels (-41%). Concurrently, fecal total steroid excretion increased (+44%) and apparent absorption of dietary cholesterol was significantly depressed (-37%) by the lettuce diet. Lettuce diet also displayed an improvement of vitamin E/TG ratio in plasma and limited lipid peroxidation in heart as evidenced by TBARS. In post-prandial experiment, lettuce intake significantly increased both ascorbic acid and alpha-tocopherol plasma levels which contribute to improve plasma antioxidant capacity within 2 h of consumption. Other lipid-soluble antioxidants (lutein and vitamin E) may also improve the plasma antioxidant capacity.

CONCLUSION

Lettuce consumption increases the total cholesterol end-products excretion and improves antioxidant status due to the richness in antioxidants (vitamins C, E and carotenoids). In our model, lettuce clearly shows a beneficial effect on lipid metabolism and on tissue oxidation. Therefore regular consumption of lettuce should contribute to improve protection against cardiovascular diseases.

Dietary fiber–rich colloids from apple pomace extraction juices do not affect food intake and blood serum lipid levels, but enhance fecal excretion of steroids in rats

The aim of this study was to investigate the effects of colloids isolated from apple pomace extraction juices (so-called B-juices) produced by enzymatic liquefaction on food intake, levels of blood serum lipids, and fecal excretion of bile acids (BA) and neutral sterols (NS) in vivo. Ten male Wistar rats per group were fed diets containing either no apple dietary fiber (DF) (control), a 5% supplementation with juice colloids, or an alcohol-insoluble substance (AIS) from apples for 6 weeks. Apple DF in diets led to lower weight gain in rats fed with B-juice colloids (P< 0.05). For these rats, food intake was not affected but was highest with feeding AIS (10% more than control) to cover energy requirements. The supplementation of diet with apple DF from extraction juices or AIS had minor effects on blood serum lipids. In rats fed either juice colloids or AIS, up to 30% (5.31 micromol/g dry weight) and 88% (7.69 micromol/g dry weight) more primary BA were excreted in feces, respectively, as compared to that in the control group (4.10 micromol/g dry weight) (P < 0.05). In cecal contents, a 15% (juice colloids) to 37% (AIS) increase in primary BA was found. In contrast, concentrations of secondary BA were lower in feces of test groups (P < 0.05). Excretion of total BA and NS was higher in rats fed apple DF (P < 0.05). Our study is the first to prove that there are beneficial physiologic effects of apple DF isolated from pomace extraction juices produced by enzymatic liquefaction. These results may help to develop such innovative juice products that are rich in DF of fruit origin for diminishing the lack of DF intake.

Effect of structure and form on the ability of plant sterols to inhibit cholesterol absorption in hamsters

We investigated the effect of three types of plant sterols (4-desmethylsterols, 4,4'-dimethylsterols, and pentacyclic triterpene alcohols) in three forms (free, esterified with FA, or with phenolic acids) on cholesterol absorption. Plant sterol fractions derived from soybean (99% 4-desmethylsterols), rice bran (70% 4,4'-dimethylsterols), or shea nut (89% pentacyclic triterpene alcohols) were fed to male hamsters (n = 20/group) as free sterols or esterified with FA or phenolic acids (cinnamic or ferulic). Cholesterol absorption was measured after 5-8.5 (mean, 7) wk by a dual-isotope technique. Soybean sterol intake significantly reduced cholesterol absorption efficiency (23%) and plasma total cholesterol (11%). Rice bran sterols tended to lower cholesterol absorption efficiency by 7% and plasma total cholesterol by 5%, whereas shea nut sterols had no effect. In hamsters, dietary 4-desmethylsterols were more effective than 4,4'-dimethylsterols in lowering cholesterol absorption and levels of cholesterol in blood. Pentacyclic triterpene alcohols had no effect on the absorption of cholesterol or on its level in blood. Esterification with FA did not impair the ability of 4-desmethylsterols and 4,4'-dimethylsterols to inhibit cholesterol absorption, whereas esterification with phenolic acids reduced this ability. This study supports the use of 4-desmethylsterols, esterified with FA to increase solubility, as the most effective cholesterol-lowering plant sterols in the diet.

Carbohydrate and Fiber Recommendations for Individuals with Diabetes: A Quantitative Assessment and Meta-Analysis of the Evidence

To review international nutrition recommendations with a special emphasis on carbohydrate and fiber, analyze clinical trial information, and provide an evidence-based recommendation for medical nutrition therapy for individuals with diabetes. Relevant articles were identified by a thorough review of the literature and the data tabulated. Fixed-effects meta-analyses techniques were used to obtain mean estimates of changes in outcome measures in response to diet interventions. Most international organizations recommend that diabetic individuals achieve and maintain a desirable body weight with a body mass index of </=25 kg/m(2). For diabetic subjects moderate carbohydrate, high fiber diets compared to moderate carbohydrate, low fiber diets are associated with significantly lower values for: postprandial plasma glucose, total and low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides. High carbohydrate, high fiber diets compared to moderate carbohydrate, low fiber diets are associated with lower values for: fasting, postprandial and average plasma glucose; hemoglobin A(1c); total, LDL-cholesterol, HDL-cholesterol and triglycerides. Low glycemic index diets compared to high glycemic index diets are associated with lower fasting plasma glucose values and lower glycated protein values. Based on these analyses we recommend that the diabetic individual should be encouraged to achieve and maintain a desirable body weight and that the diet should provide these percentages of nutrients: carbohydrate, >/=55%; protein, 12-16%; fat, <30%; and monounsaturated fat, 12-15%. The diet should provide 25-50 g/day of dietary fiber (15-25 g/1000 kcal). Glycemic index information should be incorporated into exchanges and teaching material.

Sweeteners and Beta-Glucans Improve Metabolic and Anthropometrics Variables in Well Controlled Type 2 Diabetic Patients

The introduction of fat and carbohydrates replacers has been a revolutionary advance in treating obesity and diabetes mellitus. Since these materials have shown to have beneficial effects on the metabolic profiles of diabetic patients, they should be useful in designing specific foods for patients with diabetes.

OBJECTIVE

To compare metabolic and anthropometric improvements elicited by a diet based on the American Diabetic Association's nutrition recommendations with a modified, low-energy diet incorporating fat replacers and non-sucrose sweeteners.

DESIGN

A total of 16 male, well controlled type 2 diabetes patients were divided into two groups of eight; one group received the diet based on the American Diabetic Association's nutrition recommendations, and the other was fed a modified, low-calorie diet containing a fat replacer (beta-glucans derived from oats) and the sweeteners, sucralose and fructose. Both groups were maintained on their respective diets for 4 weeks. All patients performed daily aerobic exercise consisting of walking for 60 minutes. Body weight, body mass index, basal glycemia, hemoglobin HbA1C, and lipid profile were determined in each patient before starting the diets and after 4 weeks of dietary intervention.

RESULTS

Both diets produced significant improvements in weight, body mass index, lipid profile, basal glucose, and HbA1C. However, the experimental diet was superior to the American Diabetic Association's diet in improving metabolic and anthropometric profile: greater increase in HDL cholesterol and larger decreases in HbA1C, weight, and body mass index.

CONCLUSIONS

A diet incorporating a fat replacer and non-sucrose sweeteners produced a greater improvement in metabolic and anthropometric variables in well controlled type 2 diabetic patients when compared with a diet based on American Diabetic Association's nutrition recommendations.

An in vivo study of the antioxidant potentials of a plant food concentrate

OBJECTIVE

A plant food concentrate (PF) is a source of antioxidants. Its influence on antioxidant status has never been studied. The present longitudinal study investigated the antioxidant and lipidemic responses in 15 moderately hypercholesterolemic (>5.2 mmol/L) male subjects to the supplemental intakes of PF.

METHODS

The participants underwent a two-week period where any previous supplemental intakes were withdrawn. This was followed by a two-week baseline period at entry (control). The baseline period was followed by taking PF concentrate (8.5 g twice daily) for two weeks followed by a washout period for two weeks. All subjects completed food frequency questionnaires at pre-supplemental (baseline) and post-PF period. Fasting heparinized and EDTA blood samples were collected at the end of each period. Erythrocyte superoxide dismutase (SOD), whole blood glutathione peroxidase (GPX) and plasma concentrations of zinc and copper, along with plasma levels of lipids, were determined.

RESULTS

The PF supplement contributed significantly to the daily intakes of total dietary fiber. The zinc and copper-dependent SOD but not GPX activity were significantly elevated. The total and LDL-cholesterol concentrations in the plasma were significantly decreased while the ratio of HDL/LDL cholesterol was increased post-PF intake.

CONCLUSIONS

These results indicate that the antioxidant and cholesterol status of moderately hypercholesterolemic subjects can be potentially improved with the supplemental intake of PF concentrate.

Fiber intake and risk of nonfatal acute myocardial infarction

OBJECTIVE

To investigate the association between fiber intake and risk of acute myocardial infarction (AMI), also according to type and source of fiber, in a Mediterranean country.

DESIGN

Hospital-based case-control study.

SETTING

Northern Italy.

SUBJECTS

A total of 507 cases of first nonfatal AMI and 478 controls in hospital for acute conditions.

INTERVENTIONS

Subjects were interviewed with a questionnaire that included a validated food frequency section. Odds ratios (OR) were obtained using multiple logistic regression, and adjusted for several recognized risk factors for AMI. Fiber was measured as non-starch polysaccharides.

RESULTS

Compared with the lowest one, the OR in the highest tertile was 0.72 for total fiber, 0.64 for soluble fiber, 0.77 for total insoluble fiber, 0.71 for cellulose, 0.81 for insoluble non-cellulosic polysaccharides, 0.82 for vegetable fiber, 0.64 for fruit fiber and 1.11 for cereal fiber, and the estimates were statistically significant for soluble and fruit fiber. When further adjusted for beta-carotene, vitamin C and vitamin E intake, the fruit fiber still showed the strongest inverse relation, although the association was no longer significant. The protective effect of fiber was more marked in, or restricted to, subjects with other AMI risk factors, such as smokers, diabetics and hypertensives.

CONCLUSIONS

Though an inverse association between fiber intake and AMI risk appears established, the causality of this association is still open to debate. In this population, cereal fiber derives chiefly from refined grains, and this may explain the lack of protection by this type of fiber.

Whole grains protect against atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) is the most common cause of death in most Western countries. Nutrition factors contribute importantly to this high risk for ASCVD. Favourable alterations in diet can reduce six of the nine major risk factors for ASCVD, i.e. high serum LDL-cholesterol levels, high fasting serum triacylglycerol levels, low HDL-cholesterol levels, hypertension, diabetes and obesity. Wholegrain foods may be one the healthiest choices individuals can make to lower the risk for ASCVD. Epidemiological studies indicate that individuals with higher levels (in the highest quintile) of whole-grain intake have a 29 % lower risk for ASCVD than individuals with lower levels (lowest quintile) of whole-grain intake. It is of interest that neither the highest levels of cereal fibre nor the highest levels of refined cereals provide appreciable protection against ASCVD. Generous intake of whole grains also provides protection from development of diabetes and obesity. Diets rich in wholegrain foods tend to decrease serum LDL-cholesterol and triacylglycerol levels as well as blood pressure while increasing serum HDL-cholesterol levels. Whole-grain intake may also favourably alter antioxidant status, serum homocysteine levels, vascular reactivity and the inflammatory state. Whole-grain components that appear to make major contributions to these protective effects are: dietary fibre; vitamins; minerals; antioxidants; phytosterols; other phytochemicals. Three servings of whole grains daily are recommended to provide these health benefits.

The effect of fiber-rich carbohydrates on features of Syndrome X

There has been much debate among nutritionists and scientists regarding the optimal dietary approach for the treatment of the Insulin Resistance Syndrome, also called Syndrome X. This condition, which may affect as many as 47 million individuals in the United States, significantly increases risk of coronary heart disease and stroke. Major health organizations have historically recommended high-carbohydrate, low-fat (HCLF) diets to reduce chronic disease risk. However, there is evidence that a high intake of carbohydrates may adversely affect one or more of the abnormalities associated with this syndrome. Studies in this area have often had limitations. For example, some studies showing adverse effects of an HCLF diet have not taken into account the dietary fiber content of the diet. This article describes abnormalities often associated with Syndrome X, reviews the beneficial effects of fiber-rich carbohydrates, discusses the effect of fiber-rich carbohydrates on features of this syndrome, and concludes with applications of these findings for those involved in treating individuals with features of this disorder. This review indicates that an HCLF dietary pattern such as that used in the DASH trial, with a level of dietary fiber consistent with the recommendations of the American Dietetic Association (eg, 20-35g/day), containing from 3 to 10 g soluble fiber/day, may be beneficial for treating those with Syndrome X.

Pulses and lipaemia, short- and long-term effect: potential in the prevention of cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death in most developed countries. Most CVD deaths are preventable through life-style measures such as diet, exercise and avoidance of cigarette smoking. Decreased intake of saturated fat and cholesterol and increased intake of cholesterol-reducing foods, such as pulses, deserve a high priority for activities designed to prevent CVD. Epidemiological and observational studies indicate that habitual intakes of large amounts of dietary fibre or of vegetables are associated with significantly lower rates of CVD. Studies over four decades document the hypocholesterolaemic effect of pulses and soyabeans. We performed a meta-analysis of eleven clinical trials that examined the effects of pulses (not including soyabeans) on serum lipoproteins. Intake of non-soya pulses was associated with these changes: fasting serum cholesterol, -7.2 %, 95 % CI -5.8, -8.6 %; LDL-cholesterol, -6.2 %, 95 % CI -2.8, -9.5 %; HDL-cholesterol, +2.6 %, 95 % CI +6.3, -1.0 %; triacylglycerols, -16.6 %, 95 % CI -11.8 %, -21.5 %; and body weight, -0.9 %, 95 % CI +2.2 %, -4.1 %. The hypocholesterolaemic effects of pulses appear related, in estimated order of importance, to these factors: soluble dietary fibre, vegetable protein, oligosaccharides, isoflavones, phospholipids and fatty acids, saponins and other factors. Intake of pulses may also reduce risk for CVD by favourable effects on blood pressure, glycaemia and risk for diabetes, and risk for obesity. Overall, the available evidence indicates that regular consumption of pulses may have important protective effects on risk for CVD.

Therapeutic lifestyle change and Adult Treatment Panel III: evidence then and now

The Third Report of the National Cholesterol Education Program's Adult Treatment Panel (ATP III) has an extensive section on nonpharmacologic therapy for those with abnormal blood lipids. ATP III focused on the high-saturated fat atherogenic diet, obesity, and sedentary lifestyle and recommended a program of therapeutic lifestyle change (TLC). This review discusses several issues, including 1) why ATP III changed from the Step I and Step II diets to TLC; 2) the benefits of keeping trans fatty acid intake low and the addition of viscous fiber and plant stanol/sterol esters to reduce low-density lipoprotein cholesterol beyond that seen with the Step II diet; 3) the de-emphasis on total fat and a sharper focus on the kinds of fat ingested in the new guidelines; 4) the endorsement of regular physical activity and weight loss as important first steps in reversing the unwanted metabolic effects of the metabolic syndrome; and 5) the emphasis of health-promoting aspects of the diet that include, among other things, fish and omega-3 fatty acids. At all stages of TLC, ATP III encourages the referral to registered dietitians or other qualified nutritionists for medical nutrition therapy. TLC and the ATP III guidelines should provide guidance to practitioners who wish to get low-density lipoprotein cholesterol to goal (whether or not drugs are used), prevent or treat the metabolic syndrome, and improve the overall health of the patient.

Whole-grain intake is favorably associated with metabolic risk factors for type 2 diabetes and cardiovascular disease in the Framingham Offspring Study

BACKGROUND

The influence of whole grains on cardiovascular disease risk may be mediated through multiple pathways, eg, a reduction in blood lipids and blood pressure, an enhancement of insulin sensitivity, and an improvement in blood glucose control.

OBJECTIVE

The objective was to examine the association between diets rich in whole- or refined-grain foods and several metabolic markers of disease risk in the Framingham Offspring Study cohort.

DESIGN

Whole-grain intake and metabolic risk markers were assessed in a cross-sectional study of 2941 subjects.

RESULTS

After adjustment for potential confounding factors, whole-grain intake was inversely associated with body mass index (: 26.9 in the lowest and 26.4 in the highest quintile of intake; P for trend = 0.06), waist-to-hip ratio (0.92 and 0.91, respectively; P for trend = 0.005), total cholesterol (5.20 and 5.09 mmol/L, respectively; P for trend = 0.06), LDL cholesterol (3.16 and 3.04 mmol/L, respectively; P for trend = 0.02), and fasting insulin (205 and 199 pmol/L, respectively; P for trend = 0.03). There were no significant trends in metabolic risk factor concentrations across quintile categories of refined-grain intake. The inverse association between whole-grain intake and fasting insulin was most striking among overweight participants. The association between whole-grain intake and fasting insulin was attenuated after adjustment for dietary fiber and magnesium.

CONCLUSION

Increased intakes of whole grains may reduce disease risk by means of favorable effects on metabolic risk factors.

The seeds from Plantago ovata lower plasma lipids by altering hepatic and bile acid metabolism in guinea pigs

Psyllium, the husks from Plantago ovata (PO), is recognized as a potent agent in lowering plasma cholesterol. In this study, we tested the potential hypolipidemic effects of the seeds from PO and the mechanisms associated with the lowering of plasma lipids. Male Hartley guinea pigs (n = 30; 10 per group) were fed either a control diet or diets containing 7.5 or 10 g/100 g PO for 4 wk. Diets were identical in composition except for the fiber source. The control diet contained 10 g/100 g cellulose and 2.5 g/100 g guar gum, whereas the PO diets were adjusted to a total of 12.5 g/100 g fiber with cellulose. Although a dose response was not observed, plasma triglycerides and LDL cholesterol were 34 and 23% lower in the PO groups compared with the control (P < 0.01). Lecithin cholesterol acyltransferase (LCAT) and cholesterol ester transfer protein (CETP) activities were significantly affected by the PO diets. The control group had 100 and 36% higher LCAT and CETP (P < 0.01) activities, respectively, compared with the PO groups. Hepatic total and free cholesterol concentrations were not affected by PO, but cholesteryl ester concentrations were 50% (P < 0.01) lower in the PO groups compared with the control. The activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme of cholesterol synthesis was up-regulated in the PO groups by 37%. Similarly, the activity of cholesterol 7alpha-hydroxylase, the regulatory enzyme of cholesterol catabolism to bile acids was 33% higher in the PO groups (P < 0.02). Fecal bile acids were 3 times higher in the PO groups than in the control group. These results suggest that PO exerts its hypolipidemic effect by affecting bile acid absorption and altering hepatic cholesterol metabolism.

Near-infrared analysis of soluble and insoluble dietary fiber fractions of cereal food products

The use of near-infrared (NIR) reflectance spectroscopy for the rapid and accurate measurement of soluble and insoluble dietary fiber was explored in a diverse group of cereal products. Ground samples were analyzed for soluble and insoluble dietary fiber (AOAC Method 991.43) and scanned (NIRSystems 6500 monochromator) to obtain NIR spectra. Modified PLS models were developed to predict insoluble and soluble dietary fiber using data sets expanded to include products with high fat and high sugar contents. The models predicted insoluble dietary fiber accurately with an SECV of 1.54% and an R(2) of 0.98 (AOAC determined range of 0-48.77%) and soluble dietary fiber less accurately with an SECV of 1.15% and an R(2) of 0.82 (AOAC determined range of 0-13.84%). Prediction of independent validation samples by the soluble fiber model resulted in a bias that may be related to the way the reference method treats samples with different soluble fiber constituents. The insoluble fiber model can be used to rapidly monitor insoluble dietary fiber in cereal products for nutrition labeling.

Prebiotics and lipid metabolism

Prebiotics are defined as nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth or the activity of one or a limited number of bacteria (bifidobacteria, lactobacilli) in the colon. Dietary fructans are nutritionally interesting oligosaccharides that strictly conform to the definition of prebiotics and (in view of experimental studies in animals and of less numerous studies in humans) exhibit interesting serum or hepatic lipid lowering properties. Other nondigestible/fermentable nutrients, which also modulate intestinal flora activity, exhibit cholesterol or triglyceride lowering effects. Are changes in intestinal bacterial flora composition or fermentation activity responsible for those effects? What is the future of prebiotics in the nutritional control of lipidaemia and cardiovascular disease risk in humans? Those questions only receive partial response in the present review because studies of the systemic effects of prebiotics are still in their infancy, and require fundamental research devoted to elucidating the biochemical and physiological events that allow prebiotics to exert systemic effects on lipid metabolism.

Soluble fiber and nondigestible carbohydrate effects on plasma lipids and cardiovascular risk

The association between elevated plasma LDL-cholesterol concentrations and increased risk for heart disease has made the scientific community aware of dietary sources that might effectively reduce plasma cholesterol levels. Several large-scale cohort studies have documented that dietary fiber lowers the risk for coronary heart disease. In addition, there is substantial evidence from randomized controlled clinical trials that a mean reduction of 9% in LDL-cholesterol can be achieved by intake of different sources of soluble fiber. Incorporating fiber sources into our diet may provide a useful adjunct to a low-saturated fat diet, and may have a further beneficial effect for individuals who have mild-to-moderate hypercholesterolemia. The physicochemical properties of soluble fiber result in important modifications in volume, bulk and viscosity in the intestinal lumen, which will alter metabolic pathways of hepatic cholesterol and lipoprotein metabolism, resulting in lowering of plasma LDL-cholesterol.

Dietary fiber and cardiovascular disease: experimental and epidemiologic advances

Recently reported experimental studies offer insight into the various mechanisms through which dietary fiber may reduce the risk of cardiovascular disease (CVD) in humans. Although most work has focused on traditional risk factors, studies have begun to explore less studied areas of risk such as fibrinolysis. Epidemiologic results have consistently demonstrated inverse associations between dietary fiber, particularly cereal fiber and whole grain foods, and the development of CVD morbidity and mortality. These associations have been observed in both men and women and are not accounted for by potential confounders such as other dietary and lifestyle factors; nor can they be fully explained by body habitus, antioxidants, and other nutrients found in fiber-rich foods. The evidence to date supports clear recommendations for a diet based on fiber-rich foods.

Autoantibody against oxidized low-density lipoproteins may be enhanced by cigarette smoking

A total of 59 healthy male subjects (32 smokers and 27 nonsmokers) who had no reported systemic disease and did not take alcohol and vitamin supplementation were included. The levels of autoantibody to oxidized low-density lipoproteins (ox-LDL) in smokers and age-matched nonsmokers were compared. The plasma levels of antioxidants that can affect the formation of ox-LDL were also measured, and correlation analyses between anti ox-LDL IgG and plasma antioxidants, controlling for age and body mass index (BMI), were performed. Plasma alpha-tocopherol and uric acid concentrations of nonsmokers (2.78+/-1.09 microg/mg total lipid and 6.96+/-1.69 mg/dl, respectively) were significantly higher than those of smokers (1.68+/-0.48 microg/mg total lipid and 6.15+/-1.14 mg/dl, respectively) (P<0.05). Although plasma ascorbate and retinol levels were not significantly different between smokers and nonsmokers, smokers older than 45 years old had significantly lower plasma ascorbate levels (0.32+/-0.17 mg/dl) than age-matched nonsmokers (0. 53+/-0.14 mg/dl) (P=0.036). Higher level of plasma anti ox-LDL IgG was noted in the group of smokers compared with nonsmokers (515+/-409 mU/ml vs. 407+/-268 mU/ml, respectively) under the statistic method of Chi-Square test (P=0.049). A significant negative correlation was found between plasma anti ox-LDL IgG and alpha-tocopherol in the combined population as well as in the smoker group (r=-0.26, p=0.047; r=-0.48, p=0.006; respectively). However, there was no correlation between plasma anti ox-LDL IgG and the levels of other antioxidants. These results suggest that reduced concentrations of alpha-tocopherol are associated with cigarette smoking. The significantly negative correlation between plasma anti ox-LDL IgG and alpha-tocopherol in the entire study population as well as in the smoker group suggests that plasma alpha-tocopherol may be partially effective if not totally at protecting LDL from oxidative damage caused by cigarette smoking and dietary supplementation with alpha-tocopherol may provide a protective effect against LDL oxidation, especially in smokers.

Whole grain foods and heart disease risk

Coronary heart disease (CHD) is the leading cause of death in most developed nations and is rapidly increasing in prevalence in developing countries. Death rates from cardiovascular disease exceed 1 million annually in the United States and account for the largest disease-related cost to health with total costs estimated to exceed $120 billion per annum. Many dietary factors, including total and saturated fat consumption, fruit and vegetable intake and dietary fiber, have been shown to contribute to risk for CHD. We have systematically reviewed literature from the past 20 years evaluating an association between dietary fiber and CHD. Foods that are rich in dietary fiber, including fruits, vegetables, legumes and whole grain cereals, also tend to be a rich source of vitamins, minerals, phytochemicals. antioxidants and other micronutrients. Each of these factors may be independently contributing to the cardiovascular protective effects of fiber-rich foods.

Viscous and nonviscous fibres, nonabsorbable and low glycaemic index carbohydrates, blood lipids and coronary heart disease

Viscous fibres such as guar, glucomannans, pectins, oat betaglucan and psyllium continue to be seen as hypocholesterolaemic. Nevertheless, in large cohort studies, ironically it is the insoluble cereal fibre that has been demonstrated to relate negatively to cardiovascular disease and diabetes, despite an absence of effect on fasting lipids or postprandial glycaemia. In general, resistant or nonabsorbable starch is lipid neutral, whereas some nonabsorbable sugars or oligosaccharides may raise serum cholesterol, possibly through providing more acetate after colonic fermentation by colonic microflora. On the other hand, fructo-oligosaccharides appear to reduce serum triglycerides for reasons that are not entirely clear. Of possibly greater recent interest have been the carbohydrates that are not so much resistant to absorption, but rather are slowly absorbed. They possess some of the features of dietary fibre in providing a substrate for colonic bacterial fermentation. In the small intestine, however, they form lente or sustained release carbohydrate. In the form of low glycaemic index foods, lente carbohydrate consumption has been shown to relate to improved blood lipid profiles in hyperlipidaemic individuals and improved glycaemic control in diabetes. In larger cohort studies, low glycaemic index foods or low glycaemic load diets have been associated with higher HDL-cholesterol levels and reduced incidence of diabetes and cardiovascular disease.