Diets containing pistachios reduce systolic blood pressure and peripheral vascular responses to stress in adults with dyslipidemia.

Nut consumption reduces cardiovascular risk, and reductions in blood pressure and peripheral vascular resistance may be important mediators of this relationship. We evaluated effects of pistachios on flow-mediated dilation and blood pressure response to acute stress. Twenty-eight adults with dyslipidemia completed a randomized, crossover, controlled-feeding study. All of the meals were provided and calories were controlled. After 2 weeks on a typical Western diet (35% total fat and 11% saturated fat), test diets were presented in counterbalanced order for 4 weeks each, a low-fat control diet (25% total fat and 8% saturated fat), a diet containing 10% of energy from pistachios (on average, 1 serving per day; 30% total fat and 8% saturated fat), and a diet containing 20% of energy from pistachios (on average, 2 servings per day, 34% total fat and 8% saturated fat). None of the resting hemodynamic measures significantly differed from pretreatment values. When resting and stress levels were included in the repeated-measures analysis, average reductions in systolic blood pressure were greater after the diet containing 1 serving per day versus 2 servings per day of pistachios (mean change in systolic blood pressure, -4.8 vs -2.4 mm Hg, respectively; P<0.05). After the higher dose, there were significant reductions in peripheral resistance (-62.1 dyne · s × cm(-5)) and heart rate (-3 bpm) versus the control diet (P<0.0001). These changes were partially offset by increases in cardiac output. There was no effect of diet on fasting flow-mediated dilation. Reductions in peripheral vascular constriction and the resulting decrease in hemodynamic load may be important contributors to lower risk in nut consumers.

A high legume low glycemic index diet improves serum lipid profiles in men.

Clinical studies have shown that fiber consumption facilitates weight loss and improves lipid profiles; however, the beneficial effects of high fermentable fiber low glycemic index (GI) diets under conditions of weight maintenance are unclear. In the Legume Inflammation Feeding Experiment, a randomized controlled cross-over feeding study, 64 middle-aged men who had undergone colonoscopies within the previous 2 years received both a healthy American (HA) diet (no legume consumption, fiber consumption = 9 g/1,000 kcal, and GI = 69) and a legume enriched (1.5 servings/1,000 kcal), high fiber (21 g/1,000 kcal), low GI (GI = 38) diet (LG) in random order. Diets were isocaloric and controlled for macronutrients including saturated fat; they were consumed each for 4 weeks with a 2-4 week break separating dietary treatments. Compared to the HA diet, the LG diet led to greater declines in both fasting serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) (P < 0.001 and P < 0.01, respectively). Insulin-resistant (IR) subjects had greater reductions in high density lipoprotein cholesterol (HDL-C; P < 0.01), and triglycerides (TAG)/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. Insulin-sensitive (IS) subjects had greater reductions in TC (P < 0.001), LDL-C (P < 0.01), TC/HDL-C (P < 0.01), and LDL-C/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. In conclusion, a high legume, high fiber, low GI diet improves serum lipid profiles in men, compared to a healthy American diet. However, IR individuals do not achieve the full benefits of the same diet on cardiovascular disease (CVD) lipid risk factors.

Effects of diets high in walnuts and flax oil on hemodynamic responses to stress and vascular endothelial function.

BACKGROUND: Polyunsaturated fatty acids (PUFA) have beneficial effects on cardiovascular risk, although the mechanisms are incompletely understood. In a previous article, we showed significant reductions in low-density lipoprotein cholesterol and several markers of inflammation with increasing intake of alpha-linolenic acid (ALA) from walnuts and flax. OBJECTIVE: To examine effects of ALA on cardiovascular responses to acute stress, flow-mediated dilation (FMD) of the brachial artery, and blood concentrations of endothelin-1 and arginine-vasopressin (AVP). DESIGN: Using a randomized, crossover study design, cardiovascular responses to acute stress were assessed in 20 hypercholesterolemic subjects, a subset of whom also underwent FMD testing (n  =  12). Participants were fed an average American diet (AAD) and 2 experimental diets that varied in the amount of ALA and linoleic acid (LA) that they contained. The AAD provided 8.7% energy from PUFA (7.7% LA, 0.8% ALA). On the LA diet, saturated fat was reduced, and PUFA from walnuts and walnut oil provided 16.4% of energy (12.6% LA, 3.6% ALA). On the ALA diet, walnuts, walnut oil, and flax oil provided 17% energy from PUFA (10.5% LA, 6.5% ALA). RESULTS: The ALA and LA diets significantly reduced diastolic blood pressure (-2 to -3 mm Hg) and total peripheral resistance (-4%), and this effect was evident at rest and during stress (main effect of diet, p < 0.02). FMD increased (+34%) on the diet containing additional ALA. AVP also increased by 20%, and endothelin-1 was unchanged. CONCLUSIONS: These results suggest novel mechanisms for the cardioprotective effects of walnuts and flax, and further work is needed to identify the bioactives responsible for these effects.

Consumption of a legume-enriched, low-glycemic index diet is associated with biomarkers of insulin resistance and inflammation among men at risk for colorectal cancer.

The Legume Inflammation Feeding Experiment is, to our knowledge, the first randomized crossover feeding trial testing the effects of a legume-enriched, low-glycemic index (GI) diet among men characterized for colorectal adenomas and insulin resistance (IR) status. This study was designed to test the effects of a legume-enriched diet compared with a healthy American (HA) diet under weight-stable conditions. The primary objective was to assess effects on C-reactive protein (CRP) and C-peptide levels. The secondary objective was to assess changes by IR status or history of adenomas. A total of 64 men who completed a colonoscopy within the previous 2 y consumed 2 diets in random order each for 4 wk separated by a washout period. The diets were a legume-enriched (250 g/d), low-GI (GI 38) diet and a high-GI (GI 69) HA diet. We measured fasting glucose, insulin, C-peptide, CRP, and soluble tumor necrosis factor-alpha receptors I and II (sTNFRI/II) at the beginning and end of the diet periods. Participants who consumed both the legume and HA diets had favorably improved CRP (-20.2 and -18.3%) and sTNFRI (-3.7 and -4.4%) concentrations, respectively. The sTNFRII concentrations declined marginally during the legume diet period (-3.8%; P = 0.060) and significantly during the HA diet period (-5.1%; P < 0.001). Fasting glucose increased significantly during both the legume (+1.8%) and HA (-2.2%) diet periods. Only the changes in glucose differed between the diet periods. Serum C-peptide and plasma insulin levels did not change in participants consuming either diet. Healthful dietary changes can improve biomarkers of IR and inflammation.

Effects of dairy products on intracellular calcium and blood pressure in adults with essential hypertension.

BACKGROUND: Consumption of dairy foods has been associated with lower blood pressure in certain populations. OBJECTIVE: This study examined the effects of dairy foods on blood pressure (BP) and intracellular calcium ((Ca)(i)) and the dependence of BP changes on changes in (Ca)(i). DESIGN: Twenty-three stage 1 hypertensive adults were fed the following 3 experimental diets (5 wk each) in a randomized cross-over design study; a dairy-rich, high fruits and vegetables diet (D-FandV; 30% fat, 7% saturated fat (SFA), 3.4 servings/d dairy), a high fruits and vegetables diet (FandV; 30% fat, 7% SFA, 0.4 servings/d dairy), and an average Western diet (control; 36% fat, 15% SFA, 0.4 servings/d dairy). Systolic (SBP) and diastolic (DBP) BP, calcium regulatory hormones, and erythrocyte (Ca)(i) were determined. RESULTS: SBP and DBP were significantly reduced by approximately 2 mm Hg following both D-F&V and F&V diets vs. the control (P < 0.05). The D-F&V diet significantly lowered 1,25-dihydroxyvitaminD compared with the F&V and control diets (P < 0.01). Serum calcium, parathyroid hormone, calcitonin, and renin activity were unchanged. The D-F&V diet lowered (Ca)(i) vs. the other two diets (P < 0.01), and this change correlated with the fall in DBP (r = 0.52, P < 0.05). Subjects who responded to the D-F&V diet by significantly reducing (Ca)(i) exhibited significantly greater net decreases in DBP on the D-F&V vs. the F&V (-2.8 +/- 1.0 mm Hg) and control diets (-5.4 +/-1.0 mm Hg; diet x group interaction, P < 0.02). CONCLUSION: Consumption of dairy foods beneficially affects (Ca)(i), resulting in improved BP in a subgroup defined by (Ca)(i) response.

A moderate-protein diet produces sustained weight loss and long-term changes in body composition and blood lipids in obese adults.

Diets with increased protein and reduced carbohydrates (PRO) are effective for weight loss, but the long-term effect on maintenance is unknown. This study compared changes in body weight and composition and blood lipids after short-term weight loss (4 mo) followed by weight maintenance (8 mo) using moderate PRO or conventional high-carbohydrate (CHO) diets. Participants (age = 45.4 +/- 1.2 y; BMI = 32.6 +/- 0.8 kg/m(2); n = 130) were randomized to 2 energy-restricted diets (-500 kcal/d or -2093 kJ/d): PRO with 1.6 g x kg(-1) x d(-1) protein and <170 g/d carbohydrates or CHO with 0.8 g x kg(-1) x d(-1) protein, >220 g/d carbohydrates. At 4 mo, the PRO group had lost 22% more fat mass (FM) (-5.6 +/- 0.4 kg) than the CHO group (-4.6 +/- 0.3 kg) but weight loss did not differ between groups (-8.2 +/- 0.5 kg vs. -7.0 +/- 0.5 kg; P = 0.10). At 12 mo, the PRO group had more participants complete the study (64 vs. 45%, P < 0.05) with greater improvement in body composition; however, weight loss did not differ between groups (-10.4 +/- 1.2 kg vs. -8.4 +/- 0.9 kg; P = 0.18). Using a compliance criterion of participants attaining >10% weight loss, the PRO group had more participants (31 vs. 21%) lose more weight (-16.5 +/- 1.5 vs. -12.3 +/- 0.9 kg; P < 0.01) and FM (-11.7 +/- 1.0 vs. -7.9 +/- 0.7 kg; P < 0.01) than the CHO group. The CHO diet reduced serum cholesterol and LDL cholesterol compared with PRO (P < 0.01) at 4 mo, but the effect did not remain at 12 mo. PRO had sustained favorable effects on serum triacylglycerol (TAG), HDL cholesterol (HDL-C), and TAG:HDL-C compared with CHO at 4 and 12 mo (P < 0.01). The PRO diet was more effective for FM loss and body composition improvement during initial weight loss and long-term maintenance and produced sustained reductions in TAG and increases in HDL-C compared with the CHO diet.

Effects of pistachios on cardiovascular disease risk factors and potential mechanisms of action: a dose-response study.

BACKGROUND: Nut consumption lowers cardiovascular disease (CVD) risk. Studies are lacking about the effects of pistachios, a nutrient-dense nut, on CVD risk factors, dose-response relations, and lipid-lowering mechanisms. OBJECTIVE: We evaluated the effects of 2 doses of pistachios, added to a lower-fat diet, on lipids and lipoproteins, apolipoprotein (apo)-defined lipoprotein subclasses, and plasma fatty acids. To investigate the mechanisms of action, we measured cholesteryl ester transfer protein and indexes of plasma stearoyl-CoA desaturase activity (SCD). DESIGN: In a randomized crossover controlled-feeding study, 28 individuals with LDL cholesterol > or = 2.86 mmol/L consumed 3 isoenergetic diets for 4 wk each. Baseline measures were assessed after 2 wk of a typical Western diet. The experimental diets included a lower-fat control diet with no pistachios [25% total fat; 8% saturated fatty acids (SFAs), 9% monounsaturated fatty acids (MUFAs), and 5% polyunsaturated fatty acids (PUFAs)], 1 serving/d of a pistachio diet (1 PD; 10% of energy from pistachios; 30% total fat; 8% SFAs, 12% MUFAs, and 6% PUFAs), and 2 servings/d of a pistachio diet (2 PD; 20% of energy from pistachios; 34% total fat; 8% SFAs, 15% MUFAs, and 8% PUFAs). RESULTS: The 2 PD decreased (P < 0.05 compared with the control diet) total cholesterol (-8%), LDL cholesterol (-11.6%), non-HDL cholesterol (-11%), apo B (-4%), apo B/apo A-I (-4%), and plasma SCD activity (-1%). The 1 PD and 2 PD, respectively, elicited a dose-dependent lowering (P < 0.05) of total cholesterol/HDL cholesterol (-1% and -8%), LDL cholesterol/HDL cholesterol (-3% and -11%), and non-HDL cholesterol/HDL cholesterol (-2% and -10%). CONCLUSIONS: Inclusion of pistachios in a healthy diet beneficially affects CVD risk factors in a dose-dependent manner, which may reflect effects on SCD.

The effect of walnut intake on factors related to prostate and vascular health in older men.

BACKGROUND: Tocopherols may protect against prostate cancer and cardiovascular disease (CVD). METHODS: We assessed the effect of walnuts, which are rich in tocopherols, on markers of prostate and vascular health in men at risk for prostate cancer. We conducted an 8-week walnut supplement study to examine effects of walnuts on serum tocopherols and prostate specific antigen (PSA). Subjects (n = 21) consumed (in random order) their usual diet +/- a walnut supplement (75 g/d) that was isocalorically incorporated in their habitual diets. Prior to the supplement study, 5 fasted subjects participated in an acute timecourse experiment and had blood taken at baseline and 1, 2, 4, and 8 h after consuming walnuts (75 g). RESULTS: During the timecourse experiment, triglycerides peaked at 4 h, and gamma-tocopherol (gamma-T) increased from 4 to 8 h. Triglyceride - normalized gamma-T was two-fold higher (P = 0.01) after 8 versus 4 h. In the supplement study, change from baseline was +0.83 +/- 0.52 micromol/L for gamma-T, -2.65 +/- 1.30 micromol/L for alpha-tocopherol (alpha-T) and -3.49 +/- 1.99 for the tocopherol ratio (alpha-T: gamma-T). A linear mixed model showed that, although PSA did not change, the ratio of free PSA:total PSA increased and approached significance (P = 0.07). The alpha-T: gamma-T ratio decreased significantly (P = 0.01), partly reflecting an increase in serum gamma-T, which approached significance (P = 0.08). CONCLUSION: The significant decrease in the alpha-T: gamma-T ratio with an increase in serum gamma-T and a trend towards an increase in the ratio of free PSA:total PSA following the 8-week supplement study suggest that walnuts may improve biomarkers of prostate and vascular status.

A macadamia nut-rich diet reduces total and LDL-cholesterol in mildly hypercholesterolemic men and women.

Epidemiologic studies and clinical trials have demonstrated that the unique fatty acid profile of nuts beneficially affects serum lipids/lipoproteins, reducing cardiovascular disease (CVD) risk. Nuts are low in SFA and high in PUFA and monounsaturated fatty acids (MUFA). Macadamia nuts are a rich source of MUFA. A randomized, crossover, controlled feeding study (5-wk diet periods) compared a Macadamia nut-rich diet [42.5 g (1.5 ounces)/8.79 MJ (2100 kcal)] [MAC; 33% total fat (7% SFA, 18% MUFA, 5% PUFA)] vs. an average American diet [AAD; 33% total fat (13% SFA, 11% MUFA, 5% PUFA)] on the lipid/lipoprotein profile of mildly hypercholesterolemic (n = 25; 15 female, 10 male) subjects. Serum concentrations of total cholesterol (TC) and LDL cholesterol (LDL-C) following the MAC (4.94 +/- 0.17 mmol/L, 3.14 +/- 0.14 mmol/L) were lower than the AAD (5.45 +/- 0.17 mmol/L, 3.44 +/- 0.14 mmol/L; P < 0.05). The serum non-HDL cholesterol (HDL-C) concentration and the ratios of TC:HDL-C and LDL-C:HDL-C were reduced following consumption of the MAC diet (3.83 +/- 0.17, 4.60 +/- 0.24, and 2.91 +/- 0.17, respectively) compared with the AAD (4.26 +/- 0.17, 4.89 +/- 0.24, and 3.09 +/- 0.18, respectively; P < 0.05). There was no change in serum triglyceride concentration. Thus, macadamia nuts can be included in a heart-healthy dietary pattern that reduces lipid/lipoprotein CVD risk factors. Nuts as an isocaloric substitute for high SFA foods increase the proportion of unsaturated fatty acids and decrease SFA, thereby lowering CVD risk.

The effects of a whole grain-enriched hypocaloric diet on cardiovascular disease risk factors in men and women with metabolic syndrome.

BACKGROUND: Whole-grain foods are associated in observational studies with a lower body mass index and lower cardiovascular disease (CVD) risk. However, few clinical trials have tested whether incorporating whole grains into a hypocaloric diet increases weight loss and improves CVD risk factors. OBJECTIVE: The aim of this study was to determine whether including whole-grain foods in a hypocaloric (reduced by 500 kcal/d) diet enhances weight loss and improves CVD risk factors. DESIGN: Obese adults (25 M, 25 F) with metabolic syndrome were randomly assigned to receive dietary advice either to avoid whole-grain foods or to obtain all of their grain servings from whole grains for 12 wk. All participants were given the same dietary advice in other respects for weight loss. RESULTS: Body weight, waist circumference, and percentage body fat decreased significantly (P<0.001) in both groups over the study period, but there was a significantly (P=0.03) greater decrease in percentage body fat in the abdominal region in the whole-grain group than in the refined-grain group. C-reactive protein (CRP) decreased 38% in the whole-grain group independent of weight loss but was unchanged in the refined-grain group (P=0.01 for group x time interaction). Total, LDL, and HDL cholesterol decreased in both diet groups (P<0.05). Dietary fiber and magnesium intakes increased in the whole-grain but not the refined-grain group (P=0.007 and P<0.001, respectively, for group x time interaction). CONCLUSIONS: Both hypocaloric diets were effective means of improving CVD risk factors with moderate weight loss. There were significantly (P<0.05) greater decreases in CRP and percentage body fat in the abdominal region in participants consuming whole grains than in those consuming refined grains.

Relative fat oxidation is higher in children than adults.

BACKGROUND: Prepubescent children may oxidize fatty acids more readily than adults. Therefore, dietary fat needs would be higher for children compared with adults. The dietary fat recommendations are higher for children 4 to 18 yrs (i.e., 25 to 35% of energy) compared with adults (i.e., 20 to 35% of energy). Despite this, many parents and children restrict dietary fat for health reasons. METHODS: This study assessed whether rates of fat oxidation are similar between prepubescent children and adults. Ten children (8.7 +/- 1.4 yr, 33 +/- 13 kg mean +/- SD) in Tanner stage 1 and 10 adults (41.6 +/- 8 yr, 74 +/- 13 kg) were fed a weight maintenance diet for three days to maintain body weight and to establish a consistent background for metabolic rate measurements (all foods provided). Metabolic rate was measured on three separate occasions before and immediately after breakfast and for 9 hrs using a hood system (twice) or a room calorimeter (once) where continuous metabolic measurements were taken. RESULTS: During all three sessions whole body fat oxidation was higher in children (lower RQ) compared to adults (mean RQ= 0.84 +/- .016 for children and 0.87 +/- .02, for adults, p < 0.02). Although, total grams of fat oxidized was similar in children (62.7 +/- 20 g/24 hrs) compared to adults (51.4 +/- 19 g/24 hrs), the grams of fat oxidized relative to calorie expenditure was higher in children (0.047 +/- .01 g/kcal, compared to adults (0.032 +/- .01 p < 0.02). Females oxidized more fat relative to calorie expenditure than males of a similar age. A two way ANOVA showed no interaction between gender and age in terms of fat oxidation. CONCLUSION: These data suggest that fat oxidation relative to total calorie expenditure is higher in prepubescent children than in adults. Consistent with current dietary guidelines, a moderate fat diet is appropriate for children within the context of a diet that meets their energy and nutrient needs.