Archive

Research Area: Cardiovascular Health

Effects of a Mediterranean-style diet in cardiovascular risk factors: A randomized trial

Estruch, R., M.A. Martínez-González, D. Corella, J. Salas-Salvadó, V. Ruiz-Gutiérrez, M.I. Covas, M. Fiol, E. Gómez-Gracia, M.C. López-Sabater, E. Vinyoles, F. Arós, M. Conde, C. Lahoz, J. Lapetra. G. Sáez, E. Ros for the PREDIMED Study, 2006. Effects of a Mediterranean-style diet in cardiovascular risk factors: A randomized trial. Annals of Inter Med. 145:1-11.

Background: The Mediterranean diet has been shown to have beneficial effects on cardiovascular risk factors. Objective: To compare the short-term effects of 2 Mediterranean diets versus those of a low-fat diet on intermediate markers of cardiovascular risk. Design: Substudy of a multicenter, randomized, primary prevention trial of cardiovascular disease (Prevencio’ n con Dieta Mediterra’nea [PREDIMED] Study). Setting: Primary care centers affiliated with 10 teaching hospitals. Participants: 772 asymptomatic persons 55 to 80 years of age at high cardiovascular risk who were recruited from October 2003 to March 2004. Interventions: Participants were assigned to a low-fat diet (n=257) or to 1 of 2 Mediterranean diets. Those allocated to Mediterranean diets received nutritional education and either free virgin olive oil, 1 liter per week (n = 257), or free nuts, 30 g/d (n= 258). The authors evaluated outcome changes at 3 months. Measurements: Body weight, blood pressure, lipid profile, glucose levels, and inflammatory molecules. Results: The completion rate was 99.6%. Compared with the low-fat diet, the 2 Mediterranean diets produced beneficial changes in most outcomes. Compared with the low-fat diet, the mean changes in the Mediterranean diet with olive oil group and the Mediterranean diet with nuts group were -0.39 mmol/L (95% CI, -0.70 to -0.07 mmol/L) and -0.30 mmol/L (CI, -0.58 to -0.01 mmol/L), respectively, for plasma glucose levels; -5.9 mm Hg (CI, -8.7 to -3.1 mm Hg) and -7.1 mm Hg (CI, -10.0 to -4.1 mm Hg), respectively, for systolic blood pressure; and -0.38 (CI, -0.55 to -0.22) and -0.26 (CI, -0.42 to -0.10), respectively, for the cholesterol-high-density lipoprotein cholesterol ratio. The Mediterranean diet with olive oil reduced C-reactive protein levels by 0.54 mg/L (CI, 1.04 to 0.03 mg/L) compared with the low-fat diet. Limitations: This short-term study did not focus on clinical outcomes. Nutritional education about low-fat diet was less intense than education about Mediterranean diets. Conclusion: Compared with a low-fat diet, Mediterranean diets supplemented with olive oil or nuts have beneficial effects on cardiovascular risk factors.

Effects of protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids: results of the OmniHeart randomized trial

Appel, L.J., F.M. Sacks, V.J. Carey, E. Obarzanek, J.F. Swain, E.R. Miller III, P.R. Conlin, T.P. Erlinger, B.A. Rosner, N.M. Laranjo, J. Charleston, P. McCarron, L.M. Bishop for the OmniHeart Collaborative Research Group, 2005. Effects of Protein, Monounsaturated Fat, and Carbohydrate Intake on Blood Pressure and Serum Lipids: Results of the OmniHeart Randomized Trial. JAMA. 294:2455-2464.

Context Reduced intake of saturated fat is widely recommended for prevention of cardiovascular disease. The type of macronutrient that should replace saturated fat remains uncertain. Objective To compare the effects of 3 healthful diets, each with reduced saturated fat intake, on blood pressure and serum lipids. Design, Setting, and Participants Randomized, 3-period, crossover feeding study (April 2003 to June 2005) conducted in Baltimore, Md, and Boston, Mass. Participants were 164 adults with pre-hypertension or stage 1 hypertension. Each feeding period lasted 6 weeks and body weight was kept constant. Interventions A diet rich in carbohydrates; a diet rich in protein, about half from plant sources; and a diet rich in unsaturated fat, predominantly monounsaturated fat. Main Outcome Measures Systolic blood pressure and low-density  lipoprotein cholesterol. Results Blood pressure, low-density lipoprotein cholesterol, and estimated coronary heart disease risk were lower on each diet compared with baseline. Compared with the carbohydrate diet, the protein diet further decreased mean systolic blood pressure by 1.4 mm Hg (P = .002) and by 3.5 mm Hg (P=.006) among those with hypertension and decreased low-density lipoprotein cholesterol by 3.3 mg/dL (0.09 mmol/L; P=.01), high density lipoprotein cholesterol by 1.3 mg/dL (0.03 mmol/L; P=.02), and triglycerides by 15.7 mg/dL (0.18 mmol/L; P<.001). Compared with the carbohydrate diet, the unsaturated fat diet decreased systolic blood pressure by 1.3 mm Hg (P = .005) and by 2.9 mm Hg among those with hypertension (P=.02), had no significant effect on low-density lipoprotein cholesterol, increased high-density lipoprotein cholesterol by 1.1 mg/dL (0.03 mmol/L; P=.03), and lowered triglycerides by 9.6 mg/dL (0.11 mmol/L; P=.02). Compared with the carbohydrate diet, estimated 10-year coronary heart disease risk was lower and similar on the protein and unsaturated fat diets. Conclusion In the setting of a healthful diet, partial substitution of carbohydrate with either protein or monounsaturated fat can further lower blood pressure, improve lipid levels, and reduce estimated cardiovascular risk.

Direct comparison of dietary portfolio vs statin on C-reactive protein

Jenkins, D.J.A., C.W.C. Kendall, A. Marchie, D.A. Faulkner, A.R. Josse, J.M.W. Wong, R. de Souza, A. Emam, T.L. Parker, T.J. Li, R.G. Josse, L.A. Leiter, W. Singer and P.W. Connelly. 2005. Direct comparison of dietary portfolio vs statin on C-reactive protein. Eur. J. Clin. Nutr. 59:851-860.

BACKGROUND: 3-Hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) markedly reduce serum cholesterol and have anti-inflammatory effects. The effect of cholesterol-lowering diets on inflammatory biomarkers is less well known. OBJECTIVE: To compare the efficacy of a dietary combination (portfolio) of cholesterol-lowering foods vs a statin in reducing C-reactive protein (CRP) as a biomarker of inflammation linked to increased cardiovascular disease risk. METHODS: In all, 34 hyperlipidemic subjects completed three 1-month treatments as outpatients in random order: a very low-saturated fat diet (control); the same diet with 20 mg lovastatin (statin); and a diet high in plant sterols (1.0 g/1000 kcal), soy protein (21.4 g/1000 kcal), viscous fibers (9.8 g/1000 kcal), and almonds (14 g/1000 kcal) (portfolio). Fasting blood samples were obtained at weeks 0, 2, and 4. RESULTS: Using the complete data, no treatment reduced serum CRP. However, when subjects with CRP levels above the 75th percentile for previously reported studies (> 3.5 mg/l) were excluded, CRP was reduced similarly on both statin, -16.3 +/- 6.7% (n = 23, P = 0.013) and dietary portfolio, -23.8 +/- 6.9% (n = 25, P = 0.001) but not the control, 15.3 +/- 13.6% (n = 28, P = 0.907). The percentage CRP change from baseline on the portfolio treatment (n = 25) was greater than the control (n = 28, P = 0.004) but similar to statin treatment (n = 23, P = 0.349). Both statin and portfolio treatments were similar in reducing CRP and numerically more effective than control but only the change in portfolio was significant after the Bonferroni adjustment. CONCLUSIONS: A combination of cholesterol-lowering foods reduced C-reactive protein to a similar extent as the starting dose of a first-generation statin.

Almonds in the diet simultaneously improve plasma alpha-tocopherol concentrations and reduce plasma lipids

Jambazian, P. R, E. Haddad, S. Rajaram, J. Tanzman, J. Sabaté, 2005. Almonds in the diet simultaneously improve plasma alpha-tocopherol concentrations and reduce plasma lipids. J. Am. Diet. Assoc. 105:449-454.

The objective of this study was to assess the dose response effect of almond intake on plasma and red blood cell tocopherol concentrations in healthy adults enrolled in a randomized, crossover feeding trial. Participants were 16 healthy men and women, aged 41±13 years. After a 2-week run-in period, participants were fed three diets for 4weeks each: a control diet, a low-almond diet, and a high-almond diet, in which almonds contributed 0%, 10%, and 20% of total energy, respectively. Changes in blood tocopherol levels were assayed by high pressure liquid chromatography. Incorporating almonds into the diet helped meet the revised Recommended Dietary Allowance of 15 mg/day α-tocopherol and increased lipid adjusted plasma and red blood cell α-tocopherol concentrations. A significant dose-response effect was observed between percent energy in the diet from almonds and plasma ratio of α-tocopherol to total cholesterol.

Anti-inflammatory effects of polyunsaturated fatty acids in THP-1 cells

Zhao, G., T.D. Etherton, K.R. Martin, J.P. Vanden Heuvel, P.J. Gillies, S,G. West, P.M. Kris-Etherton, 2005.  Anti-inflammatory effects of polyunsaturated fatty acids in THP-1 cells. Biochemical and Biophysical Research Communications. 336:909-17.

The effects of linoleic acid (LA), α-linolenic acid (ALA), and docosahexaenoic acid (DHA) were compared to that of palmitic acid (PA), on inflammatory responses in human monocytic THP-1 cells. When cells were pre-incubated with fatty acids for 2-h and then stimulated with lipopolysaccharide for 24-h in the presence of fatty acids, secretion of interleukin (IL)-6, IL-1b, and tumor necrosis factor-a (TNFα) was significantly decreased after treatment with LA, ALA, and DHA versus PA (P < 0.01 for all); ALA and DHA elicited more favorable effects. These effects were comparable to those for 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and were dose-dependent. In addition, LA, ALA, and DHA decreased IL-6, IL-1β, and TNFα gene expression (P < 0.05 for all) and nuclear factor (NF)-jB DNA-binding activity, whereas peroxisome proliferator-activated receptor-γ (PPARγ) DNA-binding activity was increased. The results indicate that the anti-inflammatory effects of polyunsaturated fatty acids may be, in part, due to the inhibition of NF-jB activation via activation of PPARγ.

Cardiovascular benefits of nuts

Nash, S.D., M. Westpfal, 2005.  Cardiovascular benefits of nuts. American Journal of Cardiology. 963-65.

This review article highlights some of the cardiovascular benefits of nuts. The authors conclude by writing, “Simply stated, at a time of spiraling costs for medical care, public and professional concerns about drug safety, and in an age of fad diets, it is reassuring to have a “nutty alternative.”

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

Mukuddem-Petersen, J., W. Oosthuizen, J. C. Jerling. 2005. A systematic review of the effects of nuts on blood lipid profiles in humans. J. Nutr. 135; 2082-2089.

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 ~50-100 g (~1.5-3.5 servings) of nuts ≥5 times/wk as part of a heart healthy diet with total fat content (high in mono- and/or polyunsaturated fatty acids) of ~35% of energy may significantly decrease total cholesterol and LDL cholesterol in normo- and hyperlipidemic individuals.

A nutritional intervention promoting the Mediterranean food pattern is associated with a decrease in circulating oxidized LDL particles in healthy women from the Québec City metropolitan area

Lapointe, A., J. Goulet, C. Couillard, B. Lamarche, S. Lemieux, 2005.  A nutritional intervention promoting the Mediterranean food pattern is associated with a decrease in circulating oxidized LDL particles in healthy women from the Québec City metropolitan area. J. Nutr. 135:410-15.

The aim of the present study was to evaluate the effect of a nutritional intervention promoting the Mediterranean food pattern under free-living conditions on circulating oxidized LDL (ox-LDL) in a group of 71 healthy women from the Quebec City metropolitan area. The 12-wk nutritional intervention consisted of 2 courses on nutrition and 7 individual sessions with a dietitian. A score based on the 11 components of the Mediterranean pyramid was established to determine the women’s adherence to the Mediterranean food pattern. Plasma ox-LDL concentrations were measured by a monoclonal antibody mAb-4E6–based competition ELISA. Among all women, plasma ox-LDL decreased by 11.3% after 12 wk of nutritional intervention (P < 0.0001) despite a lack of change in plasma LDL cholesterol (LDL-C). Also, an increase in the Mediterranean dietary score was significantly correlated with a decrease in ox-LDL concentrations (r=-0.30; P< 0.01). More specifically, increases in servings of fruits (r= –0.25; P<0.05) and vegetables (r= –0.24; P< 0.05) were associated with decreases in ox-LDL concentrations. Changes in the food pattern in response to a nutritional intervention promoting the Mediterranean food pattern were accompanied by beneficial effects in circulating ox-LDL concentrations in healthy women.

Dietary fiber intake and risk factors for cardiovascular disease in French adults

Lairon, D., N. Arnault, S. Bertrais, R. Planells, E. Clero, S. Hercberg, M.-C. Boutron-Ruault, 2005.  Dietary fiber intake and risk factors for cardiovascular disease in French adults.  Am J Clin Nutr.  82:1185-94.

Background: Increased consumption of dietary fiber is widely recommended to maintain or improve health, but knowledge of the relation between dietary fiber sources and cardiovascular disease risk factors is limited. Objective: We examined the relation between the source or type of dietary fiber intake and cardiovascular disease risk factors in a cohort of adult men and women. Design: In a cross-sectional study, quintiles of fiber intake were determined from dietary records, separately for 2532 men and 3429 women. Age- and multivariate-controlled logistic models investigated the odds ratios of abnormal markers for quintiles 2-5 of fiber intake compared with the lowest quintile. Results: The highest total dietary fiber and nonsoluble dietary fiber intakes were associated with a significantly (P<0.05) lower risk of overweight and elevated waist-to-hip ratio, blood pressure, plasma apolipoprotein (apo) B, apo B:apo A-I, cholesterol, triacylglycerols, and homocysteine. Soluble dietary fiber was less effective. Fiber from cereals was associated with a lower body mass index, blood pressure, and homocysteine concentration; fiber from vegetables with a lower blood pressure and homocysteine concentration; and fiber from fruit with a lower waist-to-hip ratio and blood pressure. Fiber from dried fruit or nuts and seeds was associated with a lower body mass index, waist-to-hip ratio, and fasting apo B and glucose concentrations. Fiber from pulses had no specific effect. Conclusion: Dietary fiber intake is inversely correlated with several cardiovascular disease risk factors in both sexes, which supports its protective role against cardiovascular disease and recommendations for its increased consumption.

Direct comparison of a dietary portfolio of cholesterol-lowering foods with a statin in hypercholesterolemic participants

Jenkins, D.J.A., C.W.C. Kendall, A. Marchie, D. Faulkner, J.M.W. Wong, R. de Souza, A. Emam, T.L. Parker, E. Vidgen, E.A. Trautwein, K.G Lapsley, R.G. Josse, L.A. Leiter, W. Singer, P.W. Connelly, 2005. Direct comparison of a dietary portfolio of cholesterol-lowering foods with a statin in hypercholesterolemic participants. Am J Clin Nutr. 81:380-387.

Background: 3-Hydroxy-3-methyl-glutaryl-coenzyme A (HMGCoA) reductase inhibitors reduce serum cholesterol and are increasingly advocated in primary prevention to achieve reductions in LDL cholesterol. Newer dietary approaches combining cholesterol lowering foods may offer another option, but these approaches have not been compared directly with statins in the same persons. Objective: The objective was to compare, in the same subjects, the cholesterol-lowering potential of a dietary portfolio with that of a statin. Design: Thirty-four hyperlipidemic participants underwent all three 1-mo treatments in random order as outpatients: a very-low saturated- fat diet (control diet), the same diet plus 20 mg lovastatin (statin diet), and a diet high in plant sterols (1.0 g/1000 kcal), soy protein foods (including soy milks and soy burgers, 21.4 g/1000 kcal), almonds (14 g/1000 kcal), and viscous fibers from oats, barley, psyllium, and the vegetables okra and eggplant (10 g/1000 kcal) (portfolio diets). Fasting blood samples were obtained at 0, 2, and 4 wk. Results: LDL-cholesterol concentrations decreased by 8.5 ± 1.9%, 33.3 ± 1.9%, and 29.6 ± 1.3% after 4 wk of the control, statin, and portfolio diets, respectively. Although the absolute difference between the statin and the portfolio treatments was significant at 4 wk (P = 0.013), 9 participants (26%) achieved their lowest LDL cholesterol concentrations with the portfolio diet. Moreover, the statin (n = 27) and the portfolio (n = 24) diets did not differ significantly (P = 0.288) in their ability to reduce LDL cholesterol below the 3.4-mmol/L primary prevention cutoff. Conclusions: Dietary combinations may not differ in potency from first-generation statins in achieving current lipid goals for primary prevention. They may, therefore, bridge the treatment gap between current therapeutic diets and newer statins.