Combined effect of vegetable protein (soy) and soluble fiber added to a standard cholesterol-lowering diet

Effect of a dietary intervention with functional foods on LDL-C concentrations and lipoprotein subclasses in overweight subjects with hypercholesterolemia: Results of a controlled trial

BACKGROUND & AIMS

Cardiovascular diseases (CVDs) are the leading cause of global death. Hypercholesterolemia is among the main risk factors for developing cardiovascular events, and is highly prevalent in the Mexican population. The primary objective of the present work was to assess the effect of a dietary portfolio (DP) with functional foods containing dehydrated nopal, soy protein, chia seeds, inulin, and oats in LDL-C and TC concentrations of subjects with mild hypercholesterolemia. Also, we explored the changes in the profile of the lipoprotein subclasses measured by nuclear magnetic resonance spectroscopy (NMR).

METHODS

Sixty-two subjects (47 women, 15 men) with mild hypercholesterolemia (LDL-C, ≥130 ≤ 190 mg/dL, TC > 200 mg/dL) completed the randomized, parallel, controlled study. The dietary intervention was given in two stages. First, a dietary standardization stage with a low saturated fat diet (LSFD) which matched the habitual energy intake of the volunteers for 2-weeks, followed by 2.5 months of dietary intervention with a LSFD plus placebo (PL) or DP.

RESULTS

Subjects who consumed the LSFD + DP interventions had a significantly higher reduction of LDL-C (-18.05%, P = 0.003) and TC (-17.08%, P = 0.02) compared to volunteers who consumed an LSFD for the same period. Furthermore, the lipoprotein subclass profiling showed that the small low-density-lipoproteins, and the small high-density-lipoproteins significantly decreased (P = 0.04, P < 0.001, respectively), conveying a less atherogenic state. At the end of the study, 78% of the subjects who consumed LSFD + DP reduced their LDL-C below 160 mg/dL, and of these, 47% reduced it below 130 mg/dL.

CONCLUSIONS

Based on the results obtained from this study, the inclusion of functional foods as part of the lifestyle modifications is recommended to treat mild hypercholesterolemia and reduce cardiovascular risk. Registered under ClinicalTrials.gov Identifier no. NCT04148976.

A randomized crossover trial on the effect of plant-based compared with animal-based meat on trimethylamine-N-oxide and cardiovascular disease risk factors in generally healthy adults: Study With Appetizing Plantfood-Meat Eating Alternative Trial (SWAP-MEAT)

BACKGROUND

Despite the rising popularity of plant-based alternative meats, there is limited evidence of the health effects of these products.

OBJECTIVES

We aimed to compare the effect of consuming plant-based alternative meat (Plant) as opposed to animal meat (Animal) on health factors. The primary outcome was fasting serum trimethylamine-N-oxide (TMAO). Secondary outcomes included fasting insulin-like growth factor 1, lipids, glucose, insulin, blood pressure, and weight.

METHODS

SWAP-MEAT (The Study With Appetizing Plantfood-Meat Eating Alternatives Trial) was a single-site, randomized crossover trial with no washout period. Participants received Plant and Animal products, dietary counseling, lab assessments, microbiome assessments (16S), and anthropometric measurements. Participants were instructed to consume ≥2 servings/d of Plant compared with Animal for 8 wk each, while keeping all other foods and beverages as similar as possible between the 2 phases.

RESULTS

The 36 participants who provided complete data for both crossover phases included 67% women, were 69% Caucasian, had a mean ± SD age 50 ± 14 y, and BMI 28 ± 5 kg/m2. Mean ± SD servings per day were not different by intervention sequence: 2.5 ± 0.6 compared with 2.6 ± 0.7 for Plant and Animal, respectively (P = 0.76). Mean ± SEM TMAO concentrations were significantly lower overall for Plant (2.7 ± 0.3) than for Animal (4.7 ± 0.9) (P = 0.012), but a significant order effect was observed (P = 0.023). TMAO concentrations were significantly lower for Plant among the n = 18 who received Plant second (2.9 ± 0.4 compared with 6.4 ± 1.5, Plant compared with Animal, P = 0.007), but not for the n = 18 who received Plant first (2.5 ± 0.4 compared with 3.0 ± 0.6, Plant compared with Animal, P = 0.23). Exploratory analyses of the microbiome failed to reveal possible responder compared with nonresponder factors. Mean ± SEM LDL-cholesterol concentrations (109.9 ± 4.5 compared with 120.7 ± 4.5 mg/dL, P = 0.002) and weight (78.7 ± 3.0 compared with 79.6 ± 3.0 kg, P < 0.001) were lower during the Plant phase.

CONCLUSIONS

Among generally healthy adults, contrasting Plant with Animal intake, while keeping all other dietary components similar, the Plant products improved several cardiovascular disease risk factors, including TMAO; there were no adverse effects on risk factors from the Plant products.This trial was registered at clinicaltrials.gov as NCT03718988.

Nutrition and Cardiovascular Disease: Finding the Perfect Recipe for Cardiovascular Health

The increasing burden of cardiovascular disease (CVD) despite the progress in management entails the need of more effective preventive and curative strategies. As dietary-associated risk is the most important behavioral factor influencing global health, it appears the best target in the challenge against CVD. Although for many years, since the formulation of the cholesterol hypothesis, a nutrient-based approach was attempted for CVD prevention and treatment, in recent years a dietary-based approach resulted more effective in reducing cardiovascular risk worldwide. After the publication of randomized trials on the remarkable effects of the Mediterranean diet and the Dietary Approach to Stop Hypertension (DASH) diet on CVD, new efforts were put on research about the effects of complex dietary interventions on CVD. The purpose of this paper is to review the evidence on dietary interventions in the prevention and disease modification of CVD, focusing on coronary artery disease and heart failure, the main disease responsible for the enormous toll taken by CVD worldwide.

Expansion and functional properties of extruded snacks enriched with nutrition sources from food processing by-products

Rich sources of protein and dietary fiber from food processing by-products, defatted soybean meal, germinated brown rice meal, and mango peel fiber, were added to corn grit at 20 % (w/w) to produce fortified extruded snacks. Increase of total dietary fiber from 4.82 % (wb) to 5.92-17.80 % (wb) and protein from 5.03 % (wb) to 5.46-13.34 % were observed. The product indicated high expansion and good acceptance tested by sensory panels. There were 22.33-33.53 and 5.30-11.53 fold increase in the phenolics and antioxidant activity in the enriched snack products. The effects of feed moisture content, screw speed, and barrel temperature on expansion and nutritional properties of the extruded products were investigated by using response surface methodology. Regression equations describing the effect of each variable on the product responses were obtained. The snacks extruded with feed moisture 13-15 % (wb) and extrusion temperature at 160-180 °C indicated the products with high preference in terms of expansion ratio between insoluble dietary fiber and soluble dietary fiber balance. The results showed that the by-products could be successfully used for nutritional supplemented expanded snacks.

Food combinations for cholesterol lowering

Reducing elevated LDL-cholesterol is a key public health challenge. There is substantial evidence from randomised controlled trials (RCT) that a number of foods and food components can significantly reduce LDL-cholesterol. Data from RCT have been reviewed to determine whether effects are additive when two or more of these components are consumed together. Typically components, such as plant stanols and sterols, soya protein, β-glucans and tree nuts, when consumed individually at their target rate, reduce LDL-cholesterol by 3-9 %. Improved dietary fat quality, achieved by replacing SFA with unsaturated fat, reduces LDL-cholesterol and can increase HDL-cholesterol, further improving blood lipid profile. It appears that the effect of combining these interventions is largely additive; however, compliance with multiple changes may reduce over time. Food combinations used in ten 'portfolio diet' studies have been reviewed. In clinical efficacy studies of about 1 month where all foods were provided, LDL-cholesterol is reduced by 22-30 %, whereas in community-based studies of >6 months' duration, where dietary advice is the basis of the intervention, reduction in LDL-cholesterol is about 15 %. Inclusion of MUFA into 'portfolio diets' increases HDL-cholesterol, in addition to LDL-cholesterol effects. Compliance with some of these dietary changes can be achieved more easily compared with others. By careful food component selection, appropriate to the individual, the effect of including only two components in the diet with good compliance could be a sustainable 10 % reduction in LDL-cholesterol; this is sufficient to make a substantial impact on cholesterol management and reduce the need for pharmaceutical intervention.

Low-fat diets for acquired hypercholesterolaemia

BACKGROUND

Hypercholesterolaemia, characterised by raised blood cholesterol levels, is not a disease itself but a metabolic derangement that often contributes to many diseases, notably cardiovascular disease. In most cases, elevated cholesterol levels are associated with high-fat diet, especially saturated fat, coupled with an inactive lifestyle. Less commonly, raised cholesterol may be related to an inherited disorder, familial hypercholesterolaemia. This systematic review is only concerned with acquired hypercholesterolaemia.

OBJECTIVES

To assess the effects of low-fat diets for acquired hypercholesterolaemia and to investigate the incidence of adverse effects from low-fat dietary interventions. We planned to compare the relative effectiveness of low-fat diets with calorie-restricted diets for acquired hypercholesterolaemia. We also wanted to look into the relative effectiveness of low-fat diets and pharmacological interventions for acquired hypercholesterolaemia.

SEARCH STRATEGY

Studies were obtained from computerised searches of The Cochrane Library, MEDLINE, EMBASE and databases of ongoing trials. Date of last search was February 2010.

SELECTION CRITERIA

Otherwise healthy adults (equal to or greater than 18 years) with acquired (not familial) hypercholesterolaemia. We defined hypercholesterolaemia as either total cholesterol greater than 5.2 mmol/L, LDL-cholesterol greater than 3.0 mmol/L, HDL-cholesterol less than 1.0 mmol/L or a combination thereof, although investigators' definitions were also accepted. We wanted to include any low-fat dietary intervention, like low-fat and low-saturated fat diets, intended to lower serum total and LDL-cholesterol or to raise HDL-cholesterol. A low-fat diet was considered as a fat calorie intake less than 20% of the total calories. The minimum duration of the intervention had to be six months. We excluded studies in unhealthy people.

DATA COLLECTION AND ANALYSIS

Two authors were planned to independently assess risk of bias and extract data.

MAIN RESULTS

No study met our inclusion criteria.

AUTHORS' CONCLUSIONS

Well designed, adequately powered randomised controlled trials investigating patient-relevant outcomes of low-fat diets for otherwise healthy people with hypercholesterolaemia are required.

Increase in HDL-C concentration by a dietary portfolio with soy protein and soluble fiber is associated with the presence of the ABCA1R230C variant in hyperlipidemic Mexican subjects

BACKGROUND

A dietary portfolio has been used to reduce blood lipids in hyperlipidemic subjects. To increase the effectiveness of these dietary treatments in specific populations, it is important to study the genetic variability associated with the development of certain types of hyperlipidemias. Low plasma high-density lipoprotein cholesterol (HDL-C) levels are the most common dyslipidemia in Mexican adults and are coupled with the presence of the ABCA1 R230C genotype. Therefore, the aim of this study was to assess the response of HDL-C concentration to a dietary portfolio in a group of Mexican hyperlipidemic subjects with ABCA1R230C (rs9282541) and R219K (rs2230806) polymorphisms.

METHODS

Forty-three hyperlipidemic subjects (20 men and 23 women) were given a low saturated fat (LSF) diet for one month, followed by a LSF diet that included 25g of soy protein and 15g of soluble fiber daily for 2months. We analyzed two ABCA1 polymorphisms and studied their association with serum lipids before and after treatment.

RESULTS

Hyperlipidemic subjects with the ABCA1 R230C genotype showed lower HDL-C concentrations at the beginning of the study and were better responders to the dietary treatment than subjects with the ABCA1 R230R genotype (+4.6% vs. +14.6%) (p=.05). According to gender and the presence of the R230C genotype, women responded more significantly to the dietary treatment, reflected by an increase of 21.9% in HDL concentration (p=.022), than women with R230R genotype who only experienced an increase of 2.7% in HDL-C concentration. There was no association between the presence of the ABCA1 R219K variant (p=.544) and HDL concentration.

CONCLUSION

Hyperlipidemic Mexican subjects with the ABCA1 R230C genotype showed lower HDL-concentrations and were better responders to dietary portfolio treatments for increasing HDL-C concentrations than subjects with the R230R genotype.

Fiber facts: benefits and recommendations for individuals with type 2 diabetes

In randomized controlled trials, viscous soluble fibers have demonstrated acute and long-term metabolic improvements in type 2 diabetes, such as reductions in hemoglobin A1c, fasting and post-prandial glycemia, insulinemia, and cardiovascular risk factors. In addition, they may be helpful in weight control through promoting feelings of fullness. Increasing consumption of foods containing fiber or use of fiber supplements could play an important role in managing diabetes with positive outcomes on vascular complications and reduced cardio-vascular disease risk.

Preventing and managing cardiometabolic risk: the logic for intervention

Cardiometabolic risk (CMR), also known as metabolic syndrome or insulin resistance syndrome, comprises obesity (particularly central or abdominal obesity), high triglycerides, low HDL, elevated blood pressure, and elevated plasma glucose. Leading to death from diabetes, heart disease, and stroke, the root cause of CMR is inadequate physical activity, a Western diet identified primarily by low intake of fruits, vegetables, and whole grains, and high in saturated fat, as well as a number of yet-to-be-identified genetic factors. While the pathophysiological pathways related to CMR are complex, the universal need for adequate physical activity and a diet that emphasizes fruits and vegetables and whole grains, while minimizing food high in added sugars and saturated fat suggests that these behaviors are the appropriate focus of intervention.

[Usefulness of phyto-oestrogens in reduction of blood pressure. Systematic review and meta-analysis]

OBJECTIVES

To determine whether treatment with phyto-oestrogens or soya protein succeeds in lowering blood pressure.

DESIGN

A systematic review, evaluating all the observation studies and clinical trials, was conducted, followed by a meta-analysis to evaluate blood pressure variations in patients treated with phyto-oestrogens. SEARCH: The search strategy adopted used the terms "phyto-oestrogens," "soya meals," "hypertension," and "blood pressure."

DATA SOURCES

The data bases MEDLINE, EMBASE, Cochrane, OVID were used, without time or language restrictions. References in the relevant articles were searched for manually.

STUDY SELECTION

Two independent reviewers analysed the studies found in the search.

DATA EXTRACTION

The Jadad scale was used for the clinical trials and the numerical data in the text or referred to in tables were extracted. Evaluation was made of which observational and experimental articles showed a drop in blood pressure with phyto-oestrogens and which did not. In the meta-analysis, data on sample size, difference in blood pressure before and after intervention and standard deviation were extracted from each study. The weighted difference of means was used with the model of randomised effects. The Review Manager v4.2.9 programme was used.

RESULTS

No significant variations in blood pressure were found, whether systolic (-1.20 mm Hg; 95% CI, -2.80 to 0.41 mm Hg) or diastolic (-1.31 mm Hg; 95% CI, -2.73 to 0.11). If there were any variations, they are clinically of little importance. There was also an important degree of both statistical and clinical heterogeneity.

CONCLUSIONS

There are no statistically significant or clinically important differences in blood pressure between patients treated with phyto-oestrogens and those not treated.

Saengshik, a Formulated Health Food, Decreases Blood Glucose and Increases Survival Rate in Streptozotocin-Induced Diabetic Rats

Saengshik is a Korean "non-cooked food" that is commercially produced and marketed. Ingredients in commercial Saengshik include grains, vegetables, fruits, mushrooms, sea plants, and various functional botanicals. This study investigated the effects of Saengshik on the survival rate of streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats weighing around 190 g were randomly assigned to one of the three experimental groups: a healthy normal group (NC) and two groups with STZ-induced diabetes and fed either control diet (DC) or Saengshik diet (DS). Rats in all groups were supplied with a diet of equal energy. The animals were maintained on an experimental diet for 168 days in experiment I and for 42 days in experiment II. The body weight in the DS rats decreased less than in the DC rats in both experiments I and II. There was a trend for blood glucose level in the DS group to decrease during the experimental period in both experiments I and II. A survival rate of 50% was reached on day 49 in the DC group and on day 118 in the DS group. All rats in the DC group died by day 140, while 50% of the rats in the DS group were still alive on day 168, when experiment I was terminated. In experiment II, 50% of the DC group and 90% of the DS group survived at day 42. Saengshik did not have any influence on cholesterol levels, thiobarbituric acid-reactive substances, and activities of superoxide dismutase and glutathione peroxidase. These results suggest that blood glucose concentrations and the survival rate are positively affected by Saengshik feeding in diabetic rats.

Association of blood pressure with intake of soy products and other food groups in Japanese men and women

BACKGROUND

Soy diet has been suggested to have antihypertensive effect in animal studies. The present study examined the cross-sectional relationship between blood pressure and intake of soy products and other food groups in Japanese men and women.

METHODS

Blood pressure was measured in Japanese 294 men and 330 women (246 premenopausal and 84 peri- and postmenopausal women) who participated in a health check-up program provided by a general hospital. Intake of various food groups and nutrients was estimated from a validated semiquantitative food frequency questionnaire.

RESULTS

In men, soy product intake was inversely significantly correlated with diastolic blood pressure (r = -0.12, P = 0.04) after controlling for age, total energy, smoking status, body mass index, and intake of alcohol, salt and seaweeds. The correlation of soy product intake with systolic blood pressure was of borderline significance (r = -0.10, P = 0.09). Systolic blood pressure was inversely correlated with intake of vegetables (r = -0.12, P = 0.04) and dairy products (r = -0.12, P = 0.05). There were no significant correlations between soy product intake and diastolic blood pressure in women.

CONCLUSIONS

These results indicate a mild effect of soy intake on blood pressure reduction in men.

Seasonal variation in insulin sensitivity in healthy elderly people

OBJECTIVE

There is a seasonal variation in the incidence of diabetes mellitus and cardiovascular diseases. However, there is very little information about the seasonal variation in insulin sensitivity. We report the seasonal variation in insulin sensitivity in a group of elderly subjects followed for 1 y.

METHODS

Healthy elderly (>/=70 y) subjects living independently were included. Fifty percent of subjects received a daily nutritional supplement that provided 400 kcal, 15 g of protein, and 50% of vitamin daily reference values (DRVs). Those receiving and not receiving supplements were randomly assigned to a resistance exercise training program. Every 6 mo (winter, summer, and winter), body composition was measured by dual-energy x-ray absorptiometry and blood samples were used to measure serum lipids, fasting and postprandial glucose, and insulin levels.

RESULTS

One hundred eight subjects (31 supplemented and trained, 28 supplemented, 16 trained, and 33 without supplementation or training) completed the follow up. Higher homeostasis assessment of insulin sensitivity, postprandial insulin, and fasting triacylglycerol levels were observed during the summer than during the winter. Body fat increased steadily during the study period, and fat-free mass did not change. Serum low-density lipoprotein cholesterol decreased significantly in the supplemented and trained group and increased in the non-intervention group.

CONCLUSIONS

In this group of elderly subjects, insulin resistance and triacylglycerol levels were higher during the summer. Nutritional supplementation and training had a positive effect on serum low-density lipoprotein cholesterol.

Comparison of dietary intakes of micro- and macronutrients in rural, suburban and urban populations in Costa Rica

OBJECTIVE

To compare, along with behavioural habits, the potential atherogenicity of diets in rural and urban areas in Costa Rica.

DESIGN

Subjects were randomly selected from the general population in Costa Rica. A validated food-frequency questionnaire that inquired about dietary intake in the previous year was administered once to each subject. Each subject provided plasma and an adipose tissue biopsy, which were used as biomarkers for carotenoid, tocopherol and/or fatty acid intakes. Each subject also answered another questionnaire on personal profile and household characteristics.

SETTING

A dietitian visited all subjects and conducted the interviews at their homes.

SUBJECTS

Adult male and female free-living rural, suburban and urban Costa Ricans without a history of physical or mental disability.

RESULTS

Subjects in rural areas were significantly (P < 0.05) more active physically, earned less income and had a higher intake of dietary fibre than urban dwellers. Urban residents reported a significantly (P < 0.05) higher consumption of total fat, specifically unsaturated fat mostly from soyabean oil, and had higher plasma and adipose tissue tocopherol and lycopene concentrations. Interestingly, no differences in body mass index were observed.

CONCLUSIONS

These data show differences in cardiovascular disease (CVD) risk factors of rural and urban populations in Costa Rica. In rural areas, low socio-economic status and low intake of unsaturated fatty acids appear to be the prevalent CVD risk factors, while in urban areas they were low physical activity, high trans-fatty acids in the diet and adipose tissue, and low dietary fibre intake.

Effects of high- and low-isoflavone soyfoods on blood lipids, oxidized LDL, homocysteine, and blood pressure in hyperlipidemic men and women

BACKGROUND

Many of the benefits of soy have been attributed to soy isoflavones.

OBJECTIVE

The objective was to determine the effects of high- and low-isoflavone soy-protein foods on both lipid and nonlipid risk factors for coronary artery disease (CAD).

METHODS

Forty-one hyperlipidemic men and postmenopausal women participated in a study with three 1-mo diets: a low-fat dairy food control diet and high- (50 g soy protein and 73 mg isoflavones daily) and low- (52 g soy protein and 10 mg isoflavones daily) isoflavone soyfood diets. All 3 diets were very low in saturated fat (< 5% of energy) and cholesterol (< 50 mg/d). Fasting blood samples were drawn and blood pressure was measured at the start and end of each diet.

RESULTS

No significant differences were seen between the high- and low-isoflavone soy diets. Compared with the control diet, however, both soy diets resulted in significantly lower total cholesterol, estimated CAD risk, and ratios of total to HDL cholesterol, LDL to HDL cholesterol, and apolipoprotein B to A-I. No significant sex differences were observed, except for systolic blood pressure, which in men was significantly lower after the soy diets than after the control diet. On the basis of blood lipid and blood pressure changes, the calculated CAD risk was significantly lower with the soy diets, by 10.1 +/- 2.7%.

CONCLUSION

Substitution of soyfoods for animal products, regardless of isoflavone concentration, reduces the CAD risk because of both modest reductions in blood lipids and reductions in oxidized LDL, homocysteine, and blood pressure.

The cardiovascular effects of soy products

In human clinical intervention trials, soy product consumption reduced levels of total cholesterol and low-density lipoprotein cholesterol (LDL-C). In October 1999, the US Food and Drug Administration approved a health claim for the relationship between consumption of soy protein and reduced risk of coronary heart disease. This article provides an overview of the cardiovascular effects of various soy products, including their effects on blood lipids, LDL-C oxidation, blood pressure, and vascular reactivity. Potential mechanisms of effect are discussed, emphasizing human clinical intervention trials. Soy consumption improves plasma lipids, although this effect appears to be more pronounced in individuals with elevated cholesterol. Soy and its associated isoflavones also reduce LDL oxidation and improve vascular reactivity.

Depression of the glycemic index by high levels of beta-glucan fiber in two functional foods tested in type 2 diabetes

OBJECTIVES

To determine the extent to which beta-glucan reduces the glycemic index (GI) of oat products and whether high levels of beta-glucan impair palatability.

DESIGN

The study design was an open-label, randomized cross-over study with six treatment segments.

SETTING

Free-living outpatients.

SUBJECTS

Sixteen volunteers with type 2 diabetes (10 men, six women, 61+/-2 y, body mass index 29+/-2 kg/m(2), HbA1c 7.4+/-0.4%) were recruited from the St Michael's Hospital diabetes clinic.

INTERVENTIONS

Volunteers were given, in random order, 50 g available carbohydrate portions of: white bread; a commercial oat bran breakfast cereal (4.4 g% beta-glucan); and a prototype beta-glucan-enriched breakfast cereal and bar, both high in beta-glucan (8.1 and 6.5 g% beta-glucan, respectively) and sweetened with fructose. Capillary blood samples were taken fasting and then 30, 60, 90, 120, 150 and 180 min after the start of the meal. Palatability was recorded using two different methods.

RESULTS

The glycemic indices of the prototype beta-glucan cereal (mean+/-s.e.m.; 52+/-5) and beta-glucan bar (43+/-4.1) were significantly lower than the commercial oat bran breakfast cereal (86+/-6) and white bread (100; P<0.05). All foods were highly palatable and not significantly different. It was found that the GI of the test foods used in this study decreased by 4.0+/-0.2 units per gram of beta-glucan compared to our estimate of 3.8+/-0.6 for studies reported in the literature.

CONCLUSION

Addition of beta-glucan predictably reduces the GI while maintaining palatability. In a 50 g carbohydrate portion each gram of beta-glucan reduces the GI by 4 units, making it a useful functional food component for reducing postprandial glycemia.

SPONSORSHIP

Nestec, Switzerland.

A comparison of the effects of 2 doses of soy protein or casein on serum lipids, serum lipoproteins, and plasma total homocysteine in hypercholesterolemic subjects

BACKGROUND

Studies have shown that soy protein reduces some atherogenic lipid and lipoprotein concentrations, although lipoprotein(a) concentrations may be increased. The dose response of soy protein has not been established; neither has its effect on plasma total homocysteine.

OBJECTIVE

Our objective was to evaluate the effect of 2 doses of soy protein on lipid, lipoprotein, and homocysteine concentrations.

DESIGN

Four to 24 wk after being instructed to consume a lipid-lowering diet, 130 men and women with LDL-cholesterol concentrations > or = 4 mmol/L were studied during a parallel group trial in which 4 interventions were assigned randomly. Thirty grams isolated soy protein (ISP) and 10 g cotyledon fiber or 50 g ISP and 16.6 g cotyledon fiber or equivalent doses of casein and cellulose were consumed daily as a beverage for 16 wk.

RESULTS

When the 2 groups who consumed ISP were compared with the 2 groups who consumed casein, the differences in the net changes from baseline to week 16 in the concentrations of LDL cholesterol and plasma total homocysteine were -0.26 mmol/L (95% CI: -0.43, -0.09 mmol/L; P = 0.01) and -0.8 micromol/L (-1.4, -0.2 micromol/L; P = 0.005), respectively. The effect of the ISP dose was not significant. There were no significant differences between the 2 ISP and the 2 casein groups in changes in lipoprotein(a), HDL-cholesterol, or triacylglycerol concentrations.

CONCLUSIONS

Adding 30-50 g soy protein/d to a lipid-lowering diet significantly reduced LDL-cholesterol concentrations without increasing lipoprotein(a) concentrations. Plasma total homocysteine concentrations also decreased, suggesting a novel, possibly antiatherosclerotic effect.

Oats and soy in lipid-lowering diets for women with hypercholesterolemia: is there synergy?

OBJECTIVES

To study possible synergistic effects of oats and soy on reducing total and low-density lipoprotein cholesterol (LDL-C) concentrations in human beings and the efficacy and feasibility of including these adjustments to a National Cholesterol Education Program Step I diet. SUBJECT/SETTING: One hundred twenty-seven postmenopausal women with moderate hypercholesterolemia were recruited from a large Midwestern workforce and senior centers in the surrounding community. Intervention and clinical visits were conducted in these same facilities.

DESIGN

After a 3-week lead-in period on the Step I diet, participants were randomly assigned to 1 of 4 dietary treatments for an additional 6 weeks: an oats/milk group, a wheat/soy group, an oats/soy group, and a wheat/milk group. Clinical measurements included blood draws, body weight and height, blood pressure, and medical history data. Three-day food records were collected at baseline and Weeks 3 and 9 of the intervention. Randomization was stratified based on the status of hormone replacement therapy and was blocked with sizes 4 or 8 for group assignment.

RESULTS

After 3 weeks on the Step I diet, total cholesterol, LDL-C, and triglyceride levels; total fat and saturated fat intake, dietary cholesterol intake, Keys score, and body mass index were all reduced. Following an additional 6 weeks on the Step I diet plus intervention, total cholesterol and LDL-C were further reduced for both the oats/soy group and oats/milk group. There were no significant further changes in total cholesterol, LDL-C, or high-density lipoprotein cholesterol levels in the wheat/soy and wheat/milk groups. Body mass index remained stable in all groups from Week 3 to Week 9.

APPLICATIONS

Nonpharmacologic dietary interventions like the Step I diet are feasible in a community setting and can produce rapid and significant lipid-lowering benefits. Daily consumption of 2 servings of oats can contribute to further lipid alterations in this population although soy intake at this dose may not. Palatability and convenience are important considerations in achieving dietary adherence.

The impact of nutritional supplementation and resistance training on the health functioning of free-living Chilean elders: results of 18 months of follow-up

Body composition changes and loss of functionality in the elderly are related to substandard diets and progressive sedentariness. The aim of this study was to assess the impact of an 18-mo nutritional supplementation and resistance training program on health functioning of elders. Healthy elders aged > or = 70 y were studied. Half of the subjects received a nutritional supplement. Half of the supplemented and nonsupplemented subjects were randomly assigned to a resistance exercise training program. Every 6 mo, a full assessment was performed. A total of 149 subjects were considered eligible for the study and 98 (31 supplemented and trained, 26 supplemented, 16 trained and 25 without supplementation or training) completed 18 mo of follow-up. Compliance with the supplement was 48%, and trained subjects attended 56% of programmed sessions. Activities of daily living remained constant in the supplemented subjects and decreased in the other groups. Body weight and fat-free mass did not change. Fat mass increased from 22.2 +/- 7.6 to 24.1 +/- 7.7 kg in all groups. Bone mineral density decreased less in both supplemented groups than in the nonsupplemented groups (ANOVA, P < 0.01). Serum cholesterol remained constant in both supplemented groups and in the trained groups, but it increased in the control group (ANOVA, P < 0.05). Upper and lower limb strength, walking capacity and maximal inspiratory pressure increased in trained subjects. In conclusion, patients who were receiving nutritional supplementation and resistance training maintained functionality, bone mineral density and serum cholesterol levels and improved their muscle strength.

High-protein diets in hyperlipidemia: effect of wheat gluten on serum lipids, uric acid, and renal function

BACKGROUND

The metabolic effects of diets high in vegetable protein have not been assessed despite much recent interest in the effect of soy proteins in reducing serum cholesterol.

OBJECTIVE

We assessed the metabolic effects of diets high in vegetable protein (specifically, wheat gluten) on serum lipids, uric acid concentrations, and renal function.

DESIGN

Twenty hyperlipidemic men and women consumed isoenergetic test (high-protein) and control metabolic diets for 1 mo in a randomized crossover design. In the high-protein diet, 11% of the total dietary energy from starch in the control bread was replaced by vegetable protein (wheat gluten), resulting in 27% of total energy from protein compared with 16% in the control diet. In other respects, the 2 diets were identical.

RESULTS

Compared with the control, the high-protein diet resulted in lower serum concentrations of triacylglycerol (by 19.2 +/- 5.6%; P = 0.003), uric acid (by 12.7 +/- 2.0%; P < 0.001), and creatinine (by 2.5 +/- 1.1%; P = 0.035) and higher serum concentrations of urea (by 42.2 +/- 5.8%; P < 0.001) and a higher 24-h urinary urea output (by 99.2 +/- 17.2%; P < 0.001). No significant differences were detected in total or HDL cholesterol or in the renal clearance of creatinine. LDL oxidation, assessed as the ratio of conjugated dienes to LDL cholesterol in the LDL fraction, was lower with the high-protein diet (by 10.6 +/- 3.6%; P = 0.009).

CONCLUSIONS

High intakes of vegetable protein from gluten may have beneficial effects on cardiovascular disease risk by reducing oxidized LDL, serum triacylglycerol, and uric acid. Further studies are required to assess the longer-term effects on renal function.

Thermal treatment improves nutritional quality of pea seeds (Pisum sativum L.) without reducing their hypocholesterolemic properties

The effects of isoproteic isoenergetic diets containing raw (RP) or extruded (EP) pea (Pisum sativum, cv. Ballet) seed meal on nutritional performance and serum lipids, amino acids and enzyme levels in growing rats were studied in two 15 d feeding experiments. Food intake and growth were greatly reduced in animals fed unsupplemented RP or EP. Both parameters were improved by addition of amino acids to the diets. Growth, apparent N digestibility, biological value and net protein utilisation values for supplemented (SRP) raw peas were however inferior to those for controls whilst with supplemented (SEP) extruded peas the values were similar to control levels. SRP and SEP also greatly reduced serum total cholesterol, LDL (VLDL) and cholesterol/HDL ratio. This may have been linked to the lower plasma lysine:arginine ratio. SRP and SEP increased kidney and adrenal weights and reduced liver weight. SRP stimulate pancreatic growth but SEP did not. Analysis of serum proteins and enzymes suggested these tissue changes did not lead to chronic disruption to gut or systemic metabolism. Extrusion treatment of peas improved their nutritional quality but did not reduce their hypocholesterolemic properties.

Beneficial effects of a soy-based dietary supplement on lipid levels and cardiovascular risk markers in type 2 diabetic subjects

OBJECTIVE

Consumption of soy protein has recently been shown to improve the blood lipid levels in nondiabetic subjects. The purpose of this study was to evaluate if a dietary supplement of soy protein, isoflavones, and cotyledon fiber (Abalon) affects cardiovascular risk markers, blood glucose, and insulin levels in type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

Twenty type 2 diabetic subjects participated in a crossover trial. They were randomized to double-blind supplementation for 6 weeks with Abalon (soy protein [50 g/day] with high levels of isoflavones [minimum 165 mg/day] and cotyledon fiber [20 g/day]) or placebo (casein [50 g/day] and cellulose [20 g/day]), separated by a 3-week wash-out period.

RESULTS

The results are expressed as means +/- SD. The percentage mean treatment difference between Abalon and placebo demonstrated significantly lower mean values after Abalon for LDL cholesterol (10 +/- 15%, P < 0.05), LDL/UHDL ratio (12 +/- 18%, P < 0.05), apolipoprotein (apo) B100 (30 +/- 38%, P < 0.01), triglycerides (22 +/- 10%, P < 0.05), and homocysteine (14 +/- 21%, P < 0.01), whereas the total cholesterol value tended to be less significant but still lower (8 +/- 15%, P < 0.08). No change occurred in HDL cholesterol, apo B100/apo A1 ratio, plasminogen activator inhibitor 1, factor VIIc, von Willebrand factor, fibrinogen, lipoprotein(a), glucose, HbA1c, or 24-h blood pressure.

CONCLUSIONS

These results indicate beneficial effects of dietary supplementation with Abalon on cardiovascular risk markers in type 2 diabetic subjects. This improvement is seen even in individuals with near-normal lipid values.

Cardiovascular disease and fiber: is insulin resistance the missing link?

Multiple mechanisms are likely for any effect of fiber on cardiovascular disease risk. One component that is described is the hypocholesterolemic activity of soluble fibers as they bind bile acids. New epidemiologic evidence indicates that fiber's modulation of insulin secretion and resistance deserves additional attention.

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.

Effect of soy protein foods on low-density lipoprotein oxidation and ex vivo sex hormone receptor activity--a controlled crossover trial

Plant-derived estrogen analogs (phytoestrogens) may confer significant health advantages including cholesterol reduction, antioxidant activity, and possibly a reduced cancer risk. However, the concern has also been raised that phytoestrogens may be endocrine disrupters and major health hazards. We therefore assessed the effects of soy foods as a rich source of isoflavonoid phytoestrogens on LDL oxidation and sex hormone receptor activity. Thirty-one hyperlipidemic subjects underwent two 1-month low-fat metabolic diets in a randomized crossover study. The major differences between the test and control diets were an increase in soy protein foods (33 g/d soy protein) providing 86 mg isoflavones/2,000 kcal/d and a doubling of the soluble fiber intake. Fasting blood samples were obtained at the start and at weeks 2 and 4, with 24-hour urine collections at the end of each phase. Soy foods increased urinary isoflavone excretion on the test diet versus the control (3.8+/-0.7 v 0.0+/-0.0 mg/d, P < .001). The test diet decreased both oxidized LDL measured as conjugated dienes in the LDL fraction (56+/-3 v 63+/-3 micromol/L, P < .001) and the ratio of conjugated dienes to LDL cholesterol (15.0+/-1.0 v 15.7+/-0.9, P = .032), even in subjects already using vitamin E supplements (400 to 800 mg/d). No significant difference was detected in ex vivo sex hormone activity between urine samples from the test and control periods. In conclusion, consumption of high-isoflavone foods was associated with reduced levels of circulating oxidized LDL even in subjects taking vitamin E, with no evidence of increased urinary estrogenic activity. Soy consumption may reduce cardiovascular disease risk without increasing the risk for hormone-dependent cancers.

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.

Diet controversies in lipid therapy

Increasing awareness of the relationship between diet and disease has prompted a notable increase in nutrition research. The focus of many of these studies continues to be on amount and type of fat in the diet. At the same time, a great deal of attention is being directed at other dietary components and their mode of action. The results are promising. More definitive answers must await future clinical trial data. However, the total dietary approach, including compliance measures, remains the foundation on which other nutrition recommendations should be based.

The effect on serum lipids and oxidized low-density lipoprotein of supplementing self-selected low-fat diets with soluble-fiber, soy, and vegetable protein foods

An increased intake of soluble fiber and soy protein may improve the blood lipid profile. To assess any additional benefit on serum lipids of providing soy protein and soluble-fiber foods to hyperlipidemic subjects already consuming low-fat, low-cholesterol therapeutic diets, 20 hyperlipidemic men and postmenopausal women completed 8-week test and control dietary treatments in a randomized crossover design as part of an ad libitum National Cholesterol Education Program (NCEP) step 2 therapeutic diet (<7% saturated fat and <200 mg/d cholesterol). During the test phase, foods high in soy, other vegetable proteins, and soluble fiber were provided. During the control phase, low-fat dairy and low-soluble-fiber foods were provided. Fasting blood lipid and apolipoprotein levels were measured at 4 and 8 weeks of each phase. On the test diet, 12 +/- 2 g/d soy protein was selected from the foods chosen. Direct comparison of test and control treatments indicated an elevated high-density lipoprotein (HDL) cholesterol concentration on the test diet (6.4% +/- 2.4%, P = .013) and a significantly reduced total to HDL cholesterol ratio (-5.9% +/- 2.3%, P = .020). The proportion of conjugated dienes in the low-density lipoprotein (LDL) cholesterol fraction was significantly reduced (8.5% +/- 3.3%, P = .020) as a marker of oxidized LDL. A combination of acceptable amounts of soy, vegetable protein, and soluble-fiber foods as part of a conventional low-fat, low-cholesterol therapeutic diet is effective in further reducing serum lipid risk factors for cardiovascular disease.

Soy protein, isoflavonoids, and risk of developing coronary heart disease

The effects of soy protein and isoflavones on blood cholesterol in humans has been variable. Maximal low- density lipoprotein cholesterol lowering appears to be modest and consistently ranges from 5% to 7%. Preliminary evidence suggests a potentially beneficial effect of the isoflavone fraction of soybeans on arterial compliance. The isoflavone fraction has been demonstrated to decrease the in vitro susceptibility of low-density lipoprotein to oxidation; the significance of this finding in vivo is unknown. It is difficult to definitively say at this time whether increased consumption of soy based products will result in a decreased risk of CHD beyond their ability to displace foods high in saturated fat and cholesterol from the diet.