Effects of a high walnut and high cashew nut diet on selected markers of the metabolic syndrome: a controlled feeding trial.

We investigated the effects of a high walnut diet and a high unsalted cashew nut diet on selected markers of the metabolic syndrome. In a randomized, parallel, controlled study design, sixty-four subjects having the metabolic syndrome (twenty-nine men, thirty-five women) with a mean age of 45 (sd 10) years and who met the selection criteria were all fed a 3-week run-in control diet. Hereafter, participants were grouped according to gender and age and then randomized into three groups receiving a controlled feeding diet including walnuts, or unsalted cashew nuts or no nuts for 8 weeks. Subjects were required to have lunch at the metabolic ward of the Nutrition Department of the North-West University (Potchefstroom Campus). Both the walnut and the unsalted cashew nut intervention diets had no significant effect on the HDL-cholesterol, TAG, total cholesterol, LDL-cholesterol, serum fructosamine, serum high-sensitivity C-reactive protein, blood pressure and serum uric acid concentrations when compared to the control diet. Low baseline LDL-cholesterol concentrations in the cashew nut group may have masked a possible nut-related benefit. Plasma glucose concentrations increased significantly (P = 0.04) in the cashew nut group compared to the control group. By contrast, serum fructosamine was unchanged in the cashew nut group while the control group had significantly increased (P = 0.04) concentrations of this short-term marker of glycaemic control. Subjects displayed no improvement in the markers of the metabolic syndrome after following a walnut diet or a cashew nut diet compared to a control diet while maintaining body weight.

Polyunsaturated fatty acid intake is adversely related to liver function in HIV-infected subjects: the THUSA study.

BACKGROUND: Dietary fat intake in the South African population is increasing. This population also has a high prevalence of HIV infection. However, information about metabolic effects of dietary fatty acids on HIV-infected subjects is lacking. OBJECTIVE: Our objective was to investigate the relation between dietary fatty acid intake and liver function in HIV-infected compared with HIV-uninfected subjects. DESIGN: This cross-sectional epidemiologic survey included a representative sample of 1854 apparently healthy black volunteers aged > or =15 y, who were recruited from 37 randomly selected sites throughout the North West province of South Africa. Data from 216 asymptomatic HIV-infected and 1604 HIV-uninfected subjects were used. RESULTS: Intakes of polyunsaturated fatty acids (PUFAs), linoleic acid (n-6), and the ratio of PUFAs to saturated fatty acids (SFAs) were positively associated with all the liver enzymes measured in HIV-infected subjects (R = 0.16-0.65). Most of these R values differed significantly from the R values for HIV-uninfected subjects. No associations were seen between liver enzymes and intakes of SFAs and monounsaturated fatty acids. Vitamin E intake was positively associated with serum gamma-glutamyl transpeptidase (R = 0.23), alanine aminotransferase (R = 0.37), and aspartate aminotransferase (R = 0.58) in HIV-infected subjects; these correlations differed significantly from those of the HIV-uninfected subjects because PUFA sources are the main carriers of vitamin E. CONCLUSIONS: The results suggest that n-6 PUFA intakes may be related to liver damage in these HIV-infected asymptomatic subjects. The reasons or mechanisms responsible are not clear, and further research is necessary to determine the optimal safe amounts for intake of n-6 PUFAs by HIV-infected subjects, especially in countries with traditionally high intakes of n-6 PUFA-rich vegetable oils.

Modulation of baroreflex sensitivity by walnuts versus cashew nuts in subjects with metabolic syndrome.

BACKGROUND: Impaired baroreflex sensitivity (BRS) is associated with cardiovascular diseases and the metabolic syndrome. Because lipid abnormalities have been associated with impaired BRS, this study aimed to determine whether diets known to improve the lipid profile, namely a diet high in polyunsaturated fatty acids (walnuts) or monounsaturated fatty acids (cashew nuts), would improve BRS in subjects with metabolic syndrome (MS). METHODS: A controlled feeding trial with a randomized, controlled, parallel study design was undertaken, which involved 62 subjects with MS. Subjects were stratified according to gender and age and were randomized into three groups receiving a control diet, or a diet high (20% energy) in walnuts or unsalted cashew nuts for 8 weeks while maintaining body weight. The BRS, C-reactive protein (CRP), and MS components were measured before and after the intervention. RESULTS: After the intervention, BRS in the walnut-fed study group decreased (P = .038) and that in the cashew-fed study group increased (P = .036), but the BRS in the control group did not change (P = .56). The percent change of the walnut versus cashew group differed (P = .019). Body mass index, waist circumference, blood pressure, high-density lipoprotein cholesterol, and triacylglycerol did not change. The fasting glucose concentrations of the cashew group increased (P = .03). CONCLUSIONS: The significant improvements in BRS obtained by a diet rich in cashew nuts underline the beneficial cardiovascular effects of nuts. However, the opposite result was obtained with a diet rich in walnuts. These significant changes observed might indicate that BRS is particularly sensitive and influenced by changes in diet without changes in obesity.

Phytosterols/stanols lower cholesterol concentrations in familial hypercholesterolemic subjects: a systematic review with meta-analysis.

BACKGROUND: To-date, reviews regarding the cholesterol lowering capacity of phytosterols/stanols have focused on normo- and hypercholesterolemic (HC) subjects. Familial hypercholestrolemia (FH) is characterized by very high low-density lipoprotein cholesterol (LDL-C) concentrations and is considered a world public health problem due to the high incidence of premature coronary heart disease (CHD) in these patients. OBJECTIVE: To conduct a systematic review that investigates the efficacy of phytosterols/stanols in lowering total cholesterol (TC) and LDL-C concentrations in FH subjects. DESIGN: Randomized controlled intervention trials with the primary objective to investigate the effects of phytosterols/stanols on lipid concentrations in FH subjects were identified through selected international journal databases and reference lists of relevant publications. Two researchers extracted data from each identified trial and only trials of sufficient quality (e.g. controlled, randomized, double-blind, good compliance, sufficient statistical power) were included in the review. The main outcome measures were differences between treatment and control groups for LDL-C, TC, high-density lipoprotein cholesterol (HDL-C) and triacylglycerol (TG). RESULTS: Six out of 13 studies were of sufficient quality. Two were excluded from the meta-analysis because the sterols were administered in the granulate form at very high dosages (12 g/day and 24 g/day) compared to the other studies that used fat spreads as vehicle with dosages ranging from 1.6-2.8 g/day. The subjects were heterozygous, aged 2-69 years with baseline TC and LDL-C concentrations of +/-7 mmol/L and +/-5.4 mmol/L, respectively. The duration of the studies ranged from 4 weeks to 3 months. Fat spreads enriched with 2.3 +/- 0.5 g phytosterols/stanols per day significantly reduced TC from 7 to 11% with a mean decrease of 0.65 mmol/L [95% CI -0.88, -0.42 mmol/L], p < 0.00001 and LDL-C from 10-15% with a mean decrease of 0.64 mmol/L [95% CI -0.86, -0.43 mmol/L], p < 0.00001 in 6.5 +/- 1.9 weeks compared to control treatment, without any adverse effects. TG and HDL-C concentrations were not affected. CONCLUSION: Phytosterols/stanols may offer an effective adjunct to the cholesterol lowering treatment strategy of FH patients.

A systematic review of the effects of nuts on blood lipid profiles in humans.

The inverse association of nut consumption and risk markers of coronary heart disease (lipids) has sparked the interest of the scientific and lay community. The objective of this study was to conduct a systematic review to investigate the effects of nuts on the lipid profile. Medline and Web of Science databases were searched from the start of the database to August 2004 and supplemented by cross-checking reference lists of relevant publications. Human intervention trials with the objective of investigating independent effects of nuts on lipid concentrations were included. From the literature search, 415 publications were screened and 23 studies were included. These papers received a rating based upon the methodology as it appeared in the publication. No formal statistical analysis was performed due to the large differences in study designs of the dietary intervention trials. The results of 3 almond (50-100 g/d), 2 peanut (35-68 g/d), 1 pecan nut (72 g/d), and 4 walnut (40-84 g/d) studies showed decreases in total cholesterol between 2 and 16% and LDL cholesterol between 2 and 19% compared with subjects consuming control diets. Consumption of macadamia nuts (50-100 g/d) produced less convincing results. In conclusion, consumption of approximately 50-100 g (approximately 1.5-3.5 servings) of nuts > or = 5 times/wk as part of a heart-healthy diet with total fat content (high in mono- and/or polyunsaturated fatty acids) of approximately 35% of energy may significantly decrease total cholesterol and LDL cholesterol in normo- and hyperlipidemic individuals.

Clustering of haemostatic variables and the effect of high cashew and walnut diets on these variables in metabolic syndrome patients.

We investigated the effect of a high walnut and cashew diet on haemostatic variables in people with the metabolic syndrome. Factor analysis was used to determine how the haemostatic variables cluster with other components of the metabolic syndrome and multiple regression to determine possible predictors. This randomized, control, parallel, controlled-feeding trial included 68 subjects who complied with the Third National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol criteria. After a 3-week run-in following the control diet, subjects were divided into three groups receiving either walnuts or cashews (20 energy%) or a control diet for 8 weeks. The nut intervention had no significant effect on von Willebrand factor antigen, fibrinogen, factor VII coagulant activity, plasminogen activator inhibitor 1 activity, tissue plasminogen activator activity or thrombin activatable fibrinolysis inhibitor. Statistically, fibrinogen clustered with the body-mass-correlates and acute phase response factors, and factor VII coagulant activity clustered with high-density lipoprotein cholesterol (HDL-C). Tissue plasminogen activator activity, plasminogen activator inhibitor 1 activity and von Willebrand factor antigen clustered into a separate endothelial function factor. HDL-C and markers of obesity were the strongest predictors of the haemostatic variables. We conclude that high walnut and cashew diets did not influence haemostatic factors in this group of metabolic syndrome subjects. The HDL-C increase and weight loss may be the main focus of dietary intervention for the metabolic syndrome. Furthermore, diet composition may have only limited effects if weight loss is not achieved.

Rosa roxburghii supplementation in a controlled feeding study increases plasma antioxidant capacity and glutathione redox state.

BACKGROUND: Rosa roxburghii (RR) is a plant of which the fruit juice has been used as a medicinal remedy for a variety of diseases. It has been proposed that the putative beneficial properties are related to its antioxidant potential. AIM OF STUDY: We investigated the contribution of a supplemented RR fruit sample on the antioxidant status in a cohort of healthy humans. METHODS: A total of 36 young, healthy and non-smoking individuals were recruited for this randomised placebo-controlled, single-blind trial. The study was diet controlled over a five-week period with a two week run-in period before participants daily received a placebo or an encapsulated supplement of RR sample. Total antioxidant capacity, glutathione redox state, glutathione reductase, glutathione peroxidase, superoxide dismutase and 8-OHdG levels were measured. RESULTS: RR supplementation significantly increased plasma antioxidant capacity (p = 0.04) and GSH:GSSG ratios in blood (p = 0.03). No significant changes in 8-OHdG levels, total glutathione levels or antioxidant modulating enzymes were detected suggesting that the observed shift of the glutathione redox state probably occurs via the antioxidant mediated protection of GSH. CONCLUSIONS: We conclude that these findings support the putative beneficial properties that have been linked to Rosa roxburghii as a dietary supplement that can enhance antioxidant status.

Foodstate vitamin C complex may beneficially affect haemostasis and fibrin network structure in hyperlipidaemic patients.

This randomized, placebo-controlled, double-blind, crossover study on 25 free-living hyperlipidaemic volunteers aspired to prove the hypothesis that supplementation for 8 weeks with a FoodState Vitamin C complex (500 mg vitamin C, 160 mg bioflavonoids, 600 mg magnesium and 900 mg vitamin B complex) may improve haemostatic factors and fibrin network structures. Of the haemostatic factors measured, only median plasmin-antiplasmin complex (PAP) and thrombin-antithrombin complex (TAT) concentrations were both significantly decreased with FoodState Vitamin C complex compared with placebo [PAP, -4.05% (-23.39, -0.23) versus 1.81% (-8.95, 8.09); TAT, -5.81% (-18.47, 0.39) versus 0.12% (-8.03, 13.5)]. As for fibrin network structures, only compaction was significantly increased from baseline to end [49.95% (47.55, 53.70) to 51.85% (48.55, 56.65)] by FoodState Vitamin C complex supplementation. No significant changes were found in plasma fibrinogen, plasminogen activator inhibitor 1 activity, tissue plasminogen activator antigen, D-dimer, serum lipids or lipoprotein (a) concentrations. In conclusion, the decreases in TAT and PAP are possibly an indication that the FoodState Vitamin C complex decreased the initiation of haemostasis, which in turn led to a compensatory reduction in fibrinolysis. FoodState Vitamin C complex may therefore be protective of cardiovascular disease by causing a new reduced steady state of haemostatic balance and less rigid clots (increased compaction).

Cardiovascular effects of oral Supplementation of vitamin C, E and folic acid in young healthy males.

Numerous observational studies showed associations of antioxidants (vitamins C and E) and folate intake with a reduced risk of cardiovascular disease, but randomized controlled clinical trials have generally not supported this hypothesis. The objective of this study was to investigate the effects of a daily dosage of 1000 mg vitamin C, 800 mg vitamin E, and 10 mg folate on markers of vascular function in 31 young healthy male adults. Cardiovascular values after a 12-week vitamin (14 subjects) or placebo (17 subjects) intervention were compared to baseline values. Cardiovascular parameters (blood pressure, stroke volume, heart rate, cardiac output, vascular resistance, arterial compliance) were measured continuously after an overnight fast under controlled circumstances with a Finometer device. Our main finding was a significant decrease (p = 0.03) in systolic blood pressure in the experimental group. No statistically significant changes were observed within other cardiovascular variables of the experimental group, but possible beneficial decreases in diastolic blood pressure and increases in arterial compliance after 12 weeks of vitamin supplementation were indicated. In conclusion, beneficial effects of antioxidants and folate were observed probably because the supplementation was used by young healthy subjects under carefully controlled conditions.

Meta-analysis of the health effects of using the glycaemic index in meal-planning.

Diabetes mellitus and CVD are some of the leading causes of mortality and morbidity. Accumulating data indicate that a diet characterised by low-glycaemic index (GI) foods may improve the management of diabetes or lipid profiles. The objective of the present meta-analysis was to critically analyse the scientific evidence that low-GI diets have beneficial effects on carbohydrate and lipid metabolism compared with high-GI diets. We searched for randomised controlled trials with a crossover or parallel design published in English between 1981 and 2003, investigating the effect of low-GI v. high-GI diets on markers for carbohydrate and lipid metabolism. Unstandardised differences in mean values were examined using the random effects model. The main outcomes were fructosamine, glycated Hb (HbA1c), HDL-cholesterol, LDL-cholesterol, total cholesterol and triacylglycerol. Literature searches identified sixteen studies that met the strict inclusion criteria. Low-GI diets significantly reduced fructosamine by -0.1 (95 % CI -0.20, 0.00) mmol/l (P=0.05), HbA1c by 0.27 (95 % CI -0.5, -0.03) % (P=0.03), total cholesterol by -0.33 (95 % CI -0.47, -0.18) mmol/l (P<0.0001) and tended to reduce LDL-cholesterol in type 2 diabetic subjects by -0.15 (95 % CI -0.31, -0.00) mmol/l (P=0.06) compared with high-GI diets. No changes were observed in HDL-cholesterol and triacylglycerol concentrations. No substantial heterogeneity was detected, suggesting that the effects of low-GI diets in these studies were uniform. Results of the present meta-analysis support the use of the GI as a scientifically based tool to enable selection of carbohydrate-containing foods to reduce total cholesterol and to improve overall metabolic control of diabetes.

Modest protective effects of isoflavones from a red clover-derived dietary supplement on cardiovascular disease risk factors in perimenopausal women, and evidence of an interaction with ApoE genotype in 49-65 year-old women.

Data suggest that soy protein, a source of isoflavones, may have favorable effects on cardiovascular risk factors. Women (n = 205), ages 49-65 y, were randomized into this double blind, placebo-controlled trial of 43.5 mg red clover-derived isoflavones/d. A total of 177 women completed the trial. There were no differences between treatments for changes from baseline to 12 mo in total cholesterol, LDL cholesterol, triglycerides, HDL cholesterol, systolic and diastolic blood pressures, fibrinogen, and plasminogen activator inhibitor type 1 (PAI-1) (P >/= 0.1). Interactions between treatment and menopausal status were significant for changes in triglycerides and PAI-1 (P = 0.02 and P = 0.01), and changes were significant among perimenopausal women. In the isoflavone and placebo groups, changes in triglycerides were -0.2 +/- 0.6 and 0.4 +/- 0.6 mmol/L, P = 0.02, and changes in PAI-1 were -3.06 +/- 5.88 and 4.95 +/- 6.25 IU/L, P = 0.004, respectively. Interactions between apolipoprotein E (apoE) genotype and treatment tended to be significant for changes in total and LDL cholesterol (P = 0.06 and P = 0.05), and differences between treatments were significant in E2/E3 women. In the isoflavone and placebo groups, changes in total cholesterol were -0.61 +/- 0.79 and 0.18 +/- 0.79 mmol/L, P = 0.03, and changes in LDL cholesterol were -0.84 +/- 0.79 and -0.04 +/- 0.69 mmol/L, P = 0.02, respectively. Although there were potentially beneficial changes in triglycerides and PAI-1 among perimenopausal women consuming isoflavones, this study suggests that isoflavones alone are not responsible for the well-documented effects of soy protein on blood lipids. A larger study is required to confirm the effect modification by apoE genotype.

The effect of red palm olein and refined palm olein on lipids and haemostatic factors in hyperfibrinogenaemic subjects.

Little is known about the physiological effects of red palm olein (RPO). The effects of red palm olein and palm olein (POL) compared to sunflower oil (SFO), on lipids, haemostatic factors and fibrin network characteristics in hyperfibrinogenaemic volunteers were investigated. Fifty-nine free-living, hyperfibrinogenaemic volunteers participated in this randomized, controlled, single blind parallel study. After a 4-week run-in, during which subjects received sunflower oil products, they were paired and randomly assigned to one of three intervention groups receiving products containing 25 g/day ( approximately 12% of total energy intake) of either red palm olein, palm olein or sunflower oil for another 4 weeks. Anthropometric measurements, blood samples and dietary intakes were measured before run-in, and before and after intervention. The differences in changes in total serum cholesterol response between palm olein and red palm olein (+0.59 vs. +0.18 mmol/l; p=0.053), and between palm olein and sunflower oil (+0.59 vs. -0.003 mmol/l; p < or =0.01) were significant. The low-density lipoprotein cholesterol (LDLC) response in the palm olein-and sunflower oil-groups also differed significantly (+0.42 vs. -0.11 mmol/l; p < or =0.01). Tissue plasminogen activator antigen (tPA(ag)) decreased significantly in the red palm olein group compared to the palm olein-and sunflower oil-groups. No effects were found in other haemostatic variables. Palm olein and red palm olein had no independent effect on fibrin network characteristics. In conclusion, compared to palm olein, red palm olein had less detrimental effects on the lipid profile and decreased tissue plasminogen activator antigen. Studies in larger groups are advised for confirmation of results, elucidation of mechanisms and effects of nonglyceride constituents of red palm oil (PO).

Sensitivity of the Finometer device in detecting acute and medium-term changes in cardiovascular function.

BACKGROUND: The Finometer (FMS, Finapres Measurement Systems, Arnhem, Netherlands), which is the improved successor of the Finapres (TNO Biomedical Instrumentation, Amsterdam, Netherlands), measures finger arterial blood pressure non-invasively and computes other cardiovascular parameters from the computed aortic-flow waveform. The usability of the Finometer would depend on whether it is sensitive enough to detect small cardiovascular changes. The aim was therefore to determine the sensitivity of the Finometer regarding acute and longer-term cardiovascular changes. DESIGN AND METHODS: The sensitivity of the Finometer regarding the acute effect of 200 mg caffeine was determined with a double-blind, placebo-controlled crossover study which included 38 young male subjects. Finometer recordings were performed during four occasions at fasting level and after 30 min of ingestion. To evaluate the sensitivity of the Finometer in recording longer-term effects of a daily dosage of 1000 mg vitamin C, 800 mg vitamin E and 10 mg folic acid, 14 young males took placebo and 17 took the vitamins for 12 weeks in a double-blind study. Two recordings were performed at baseline and two after 12 weeks. RESULTS: After caffeine ingestion significantly (P<0.05) higher systolic, diastolic and mean blood pressure values than resting values were obtained. The arterial compliance was significantly lower after caffeine ingestion, whereas heart rate, peripheral resistance, stroke volume and cardiac output did not change significantly. No differences were shown after intake of placebo. Concerning the effects of vitamin intake, the vitamin group indicated a significant decrease in systolic blood pressure (P=0.03) whereas the placebo group indicated no significant differences after 12 weeks. CONCLUSIONS: The results suggest that the improved Finometer might be a sensitive instrument in the recording of relative small acute and longer-term changes in cardiovascular function, but more studies are necessary before final conclusions can be drawn.