Feldman, E.B., 2002. LSRO Report: The scientific evidence for a beneficial health relationship between walnuts and coronary heart disease. J Nutr. 132:1062S-101S.
The author and four independent experts evaluated the intent and quality of scientific evidence for a potential beneficial health relationship between the intake of walnuts and the reduction and prevention of coronary heart disease. The report also addresses the supporting evidence for the health benefit of other tree nuts and selected legumes. Compared to most other nuts, which contain monounsaturated fatty acids, walnuts are unique because they are rich in n-6 (linoleate) and n-3 (linolenate) polyunsaturated fatty acids. Walnuts contain multiple health-beneficial components, such as having a low lysine:arginine ratio and high levels of arginine, folate, fiber, tannins, and polyphenols. Though walnuts are energy rich, clinical dietary intervention studies show that walnut consumption does not cause a net gain in body weight when eaten as a replacement food. Five controlled, peer-reviewed, human clinical walnut intervention trials, involving approximately 200 subjects representative of the 51% of the adult population in the United States at risk of coronary heart disease were reviewed. The intervention trials consistently demonstrated walnuts as part of a heart-healthy diet, lower blood cholesterol concentrations. None of these studies were of extended duration that would be essential for evaluation of the sustainability of the observed outcomes. These results were supported by several large prospective observational studies in humans, all demonstrating a dose response-related inverse association of the relative risk of coronary heart disease with the frequent daily consumption of small amounts of nuts, including walnuts.
Albert, C.M., M. Gaziano, W.C. Willett, J.E. Manson, 2002. Nut consumption and decreased risk of sudden cardiac death in the Physicians’ Health Study. Arch. Intern. Med. 162:1382.
Background: Dietary nut intake has been associated with a reduced risk of coronary heart disease mortality; however, the mechanism is unclear. Since components of nuts may have antiarrhythmic properties, part of the benefit may be due to a reduction in sudden cardiac death. – Methods: We prospectively assessed whether increasing frequency of nut consumption, as ascertained by an abbreviated food frequency questionnaire at 12 months of follow-up, was associated with a lower risk of sudden cardiac death and other coronary heart disease end points among 21454 male participants enrolled in the US Physicians’ Health Study. Participants were followed up for an average of 17 years. Results: Dietary nut intake was associated with a significantly reduced risk of sudden cardiac death after controlling for known cardiac risk factors and other dietary habits (P for trend, .01). Compared with men who rarely or never consumed nuts, those who consumed nuts 2 or more times per week had reduced risks of sudden cardiac death (relative risk, 0.53; 95% confidence interval, 0.30-0.92) and total coronary heart disease death (relative risk, 0.70; 95% confidence interval, 0.50-0.98). In contrast, nut intake was not associated with significantly reduced risks of non-sudden coronary heart disease death or nonfatal myocardial infarction. Conclusion: These prospective data in US male physicians suggest that the inverse association between nut consumption and total coronary heart disease death is primarily due to a reduction in the risk of sudden cardiac death.
Munoz, S., M. Merlos, D. Zambon, C. Rodriguez, J. Sabaté, E. Ros, J.C. Laguna, 2001. Walnut-enriched diet increases the association of LDL from hypercholesterolemic men with human HepG2 cells. J Lipid Res. 42(12):2069-76.
In a randomized, cross-over feeding trial involving 10 men with polygenic hypercholesterolemia, a control, Mediterranean-type cholesterol-lowering diet, and a diet of similar composition in which walnuts replaced approximately 35% of energy from unsaturated fat, were given for 6 weeks each. Compared with the control diet, the walnut diet reduced serum total and LDL cholesterol by 4.2% (P = 0.176), and 6.0% (P = 0.087), respectively. No changes were observed in HDL cholesterol, triglycerides, and apolipoprotein A-I levels or in the relative proportion of protein, triglycerides, phospholipids, and cholesteryl esters in LDL particles. The apolipoprotein B level declined in parallel with LDL cholesterol (6.0% reduction). Whole LDL, particularly the triglyceride fraction, was enriched in polyunsaturated fatty acids from walnuts (linoleic and alpha-linolenic acids). In comparison with LDL obtained during the control diet, LDL obtained during the walnut diet showed a 50% increase in association rates to the LDL receptor in human hepatoma HepG2 cells. LDL uptake by HepG2 cells was correlated with alpha-linolenic acid content of the triglyceride plus cholesteryl ester fractions of LDL particles (r(2) = 0.42, P < 0.05). Changes in the quantity and quality of LDL lipid fatty acids after a walnut-enriched diet facilitate receptor-mediated LDL clearance and may contribute to the cholesterol-lowering effect of walnut consumption.
Sacks, F.M., L.P. Svetkey, W.M. Vollmer, L.J. Appel, B.A. Bray, D. Harsha, E. Obarzanek, P.R. Conlin, E.R. Miller, D.G. Simons-Morton, N. Karanja, P. Lin, 2001. Effects on blood pressure of reduced dietary sodium and the dietary approaches to stop hypertension (DASH) diet. NEJM. 344(1):3-10.
Background The effect of dietary composition on blood pressure is a subject of public health importance. We studied the effect of different levels of dietary sodium, in conjunction with the Dietary Approaches to Stop Hypertension (DASH) diet, which is rich in vegetables, fruits, and low-fat dairy products, in persons with and in those without hypertension. Methods A total of 412 participants were randomly assigned to eat either a control diet typical of intake in the United States or the DASH diet. Within the assigned diet, participants ate foods with high, intermediate, and low levels of sodium for 30 consecutive days each, in random order. Results Reducing the sodium intake from the high to the intermediate level reduced the systolic blood pressure by 2.1 mm Hg (P<0.001) during the control diet and by 1.3 mm Hg (P=0.03) during the DASH diet. Reducing the sodium intake from the intermediate to the low level caused additional reductions of 4.6 mm Hg during the control diet (P<0.001) and 1.7 mm Hg during the DASH diet (P<0.01). The effects of sodium were observed in participants with and in those without hypertension, blacks and those of other races, and women and men. The DASH diet was associated with a significantly lower systolic blood pressure at each sodium level; and the difference was greater with high sodium levels than with low ones. As compared with the control diet with a high sodium level, the DASH diet with a low sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension, and 11.5 mm Hg lower in participants with hypertension. Conclusions The reduction of sodium intake to levels below the current recommendation of 100 mmol per day and the DASH diet both lower blood pressure substantially, with greater effects in combination than singly. Long-term health benefits will depend on the ability of people to make long-lasting dietary changes and the increased availability of lower-sodium foods.
Anderson et al, 2001. Walnut polyphenolics inhibit in vitro human plasma and LDL oxidation. J Nutr. 0022-3166
Recent epidemiologic studies have associated nut consumption with a reduced incidence of cardiovascular mortality. However, little is known about the contribution of nut polyphenols to antioxidant and cardiovascular protection. In this investigation, polyphenol-rich extracts from English walnuts (Juglans regia) were studied and compared with ellagic acid for their ability to inhibit in vitro plasma and LDL oxidation, as well as their effects on LDL ý-tocopherol during oxidative stress. In addition, the Trolox equivalent antioxidant activity (TEAC) was determined and liquid chromatography electrospray detection mass spectrometry (LC-ELSD/MS) analyses of the walnut extracts were performed. 2,2′-Azobis'(2-amidino propane) hydrochloride (AAPH)-induced LDL oxidation was significantly inhibited by 87 and 38% with the highest concentration (1.0 ýmol/L) of ellagic acid and walnut extract, respectively. In addition, copper-mediated LDL oxidation was inhibited by 14 and 84% in the presence of ellagic acid and walnut extract, respectively, with a modest, significant LDL ý-tocopherol sparing effect observed. Plasma thiobarbituric acid reacting substance (TBARS) formation was significantly inhibited by walnut extracts and ellagic acid in a dose-dependent manner, and the extracts exhibited a TEAC value greater than that of ý-tocopherol. LC-ELSD/MS analysis of the walnut extracts identified ellagic acid monomers, polymeric ellagitannins and other phenolics, principally nonflavonoid compounds. These results demonstrate that walnut polyphenolics are effective inhibitors of in vitro plasma and LDL oxidation. The polyphenolic content of walnuts should be considered when evaluating their antiatherogenic potential.
Almario, R.U., V. Vonghavaravat, R. Wong, S.E. Kasim-Karakas, 2001. Effects of walnut consumption on plasma fatty acids and lipoproteins in combined hyperlipidemia. Am J Clin Nutr. 74:72-9
BACKGROUND: Epidemiologic studies show an inverse relation between nut consumption and coronary heart disease. OBJECTIVE: We determined the effects of walnut intake on plasma fatty acids, lipoproteins, and lipoprotein subclasses in patients with combined hyperlipidemia. DESIGN: Participants sequentially adhered to the following diets: 1) a habitual diet (HD), 2) a habitual diet plus walnuts (HD+W), 3) a low-fat diet (LFD), and 4) a low-fat diet plus walnuts (LFD+W). RESULTS: In 13 postmenopausal women and 5 men (x ± SD age 60 ± 8 y), walnut supplementation did not increase body weight despite increased energy intake and the LFD caused weight loss (1.3 ± 0.5 kg; P < 0.01). When comparing the HD with the HD+W, linoleic acid concentrations increased from 29.94 ± 1.14% to 36.85 ±1.13% and ?-linolenic acid concentrations increased from 0.78 ± 0.04% to 1.56 ± 0.11%. During the LFD+W, plasma total cholesterol concentrations decreased by 0.58± 0.16 mmol/L when compared with the HD and by 0.46 ± 0.14 mmol/L when compared with the LFD. LDL-cholesterol concentrations decreased by 0.46 ± 0.15 mmol/L when compared with the LFD. Measurements of lipoprotein subclasses and particle size suggested that walnut supplementation lowered cholesterol preferentially in small LDL (46.1 ± 1.9% compared with 33.4 ± 4.3%, HD compared with HD+W, respectively; P < 0.01). HDL-cholesterol concentrations decreased from 1.27 ± 0.07 mmol/L during the HD to 1.14 ± 0.07 mmol/L during the HD+W and to 1.11 ± 0.08 mmol/L during the LFD. The decrease was seen primarily in the large HDL particles. Conclusions: Walnut supplementation may beneficially alter lipid distribution among various lipoprotein subclasses even when total plasma lipids do not change. This may be an additional mechanism underlying the anti-atherogenic properties of nut intake.
Rajaram, S., K. Burke, B. Connell, T. Myint, J. Sabaté, 2001. A monounsaturated fatty acid-rich pecan enriched diet favorably alters the serum lipid profile of healthy men and women. J Nutr. 131:2275.
Frequent consumption of nuts is associated with decreased risk of cardiovascular disease. We investigated the effect of pecans rich in monounsaturated fat as an alternative to the Step 1 diet in modifying serum lipids and lipoproteins in men and women with normal to moderately high serum cholesterol. In a single-blind, randomized, controlled, crossover feeding study, we assigned 23 subjects (mean age: 38 y; 9 women, 14 men) to follow two diets, each for 4 wk: a Step I diet and a pecan-enriched diet (accomplished by proportionately reducing all food items in a Step I diet by one fifth for a 20% isoenergetic replacement with pecans). The percentage of energy from fat in the two diets was 28.3 and 39.6%, respectively. Both diets improved the lipid profile; however, the pecan-enriched diet decreased both serum total and LDL cholesterol by 0.32 mmol/L (6.7 and 10.4%, respectively) and triglyceride by 0.14 mmol/L (11.1%) beyond the Step I diet, while increasing HDL cholesterol by 0.06 mmol/L (2.5 mg/dL). Serum apolipoprotein B and lipoprotein(a) decreased by 11.6 and 11.1%, respectively, and apolipoprotein A1 increased by 2.2% when subjects consumed the pecan compared with the Step I diet. These differences were all significant (P < 0.05). A 20% isoenergetic replacement of a Step I diet with pecans favorably altered the serum lipid profile beyond the Step I diet, without increasing body weight. Nuts such as pecans that are rich in monounsaturated fat may therefore be recommended as part of prescribed cholesterol-lowering diet of patients or habitual diet of healthy individuals.
Curb, J.D., G. Wergowske, J.C. Dobbs, R.D. Abbott, B. Huang, 2000. Serum lipid effects of a high-monounsaturated fat diet based on macadamia nuts. Arch Intern Med. 160(8):1154-8.
BACKGROUND: Recent studies have identified potential beneficial effects of eating nuts, most of which have substantial amounts of monounsaturated fats. Macadamia nuts are 75% fat by weight, 80% of which is monounsaturated. OBJECTIVE: To examine variations in serum lipid levels in response to a high-monounsaturated fat diet based on macadamia nuts. METHODS: A randomized crossover trial of three 30-day diets was conducted in 30 volunteers aged 18 to 53 years from a free-living population. Each was fed a –typical American– diet high in saturated fat (37% energy from fat); an American Heart Association Step 1 diet (30% energy from fat); and a macadamia nut-based monounsaturated fat diet (37% energy from fat) in random order. Serum total cholesterol, high-density lipoprotein cholesterol, and triglyceride levels were measured. RESULTS: Mean total cholesterol level after the typical American diet was 5.20 mmol/L (201 mg/dL). After the Step 1 diet and the macadamia nut diet, total cholesterol level was 4.99 mmol/L (193 mg/dL) and 4.95 mmol/L (191 mg/dL), respectively. Low-density lipoprotein cholesterol level was 3.37 mmol/L (130 mg/dL) (typical diet), 3.21 mmol/L (124 mg/dL) (Step 1 diet), and 3.22 mmol/L (125 mg/dL) (macadamia nut diet). High-density lipoprotein cholesterol level was 1.43 mmol/L (55 mg/dL) (typical), 1.34 mmol/L (52 mg/dL) (Step 1), and 1.37 mmol/L (53 mg/dL) (macadamia nut). Lipid values after the Step 1 and macadamia nut diets were significantly different from those after the typical diet (P<.05). CONCLUSIONS: The macadamia nut-based diet high in monounsaturated fat and the moderately low-fat diet both had potentially beneficial effects on cholesterol and low-density lipoprotein cholesterol levels when compared with a typical American diet. This study involved 30 subjects who consumed three different diets each for 30 days. The first diet was a typical American diet (AM), high in saturated fat, the second diet was the American Heart Association (AHA) Step 1 diet and the third diet was a macadamia based diet (MAC) high in monounsaturated fatty acids. Compared to the AM diet, the MAC diet lowered total cholesterol, LDL and HDL each by 5% and triglycerides by 10%. The AHA diet had similar results except for an 8% increase in triglycerides.
© 2010 The International Tree Nut Council Nutrition Research & Education Foundati
Kris-Etherton, P.M., G. Zhao, A.E. Binkoski, S.M. Coval, T.D. Etherton, 2001. The effects of nuts on coronary heart disease risk. Nutr Rev. 59:103.
Epidemiologic studies have consistently demonstrated beneficial effects of nut consumption on coronary heart disease (CHD) morbidity and mortality in different population groups. Clinical studies have reported total and low-density lipoprotein cholesterol-lowering effects of heart-healthy diets that contain various nuts or legume peanuts. It is evident that the favorable fatty acid profile of nuts (high in unsaturated fatty acids and low in saturated fatty acids) contributes to cholesterol lowering and, hence, CHD risk reduction. Dietary fiber and other bioactive constituents in nuts may confer additional cardioprotective effects.
Ellsworth, J.L., L.H. Kushi and A.R. Folsom, 2001. Frequent nut intake and risk of death from coronary heart disease and all causes in postmenopausal women: The Iowa Women’s Health Study. Nutr Metab Cardiovasc Dis. 11:372-7.
BACKGROUND AND AIM: Recent epidemiological studies suggest that there is an inverse association between the frequent consumption of nuts and the risk of coronary heart disease (CHD), and clinical investigations suggest that diets high in nuts may reduce serum cholesterol levels. This study assessed whether the risk of death due to CHD and all causes is reduced in postmenopausal women who frequently consume nuts. METHODS AND RESULTS: In 1986, 34,111 postmenopausal women with no known cardiovascular disease reported the frequency of their consumption of nuts and other foods, as well as other CHD risk factors. During approximately 12 years of follow-up, 3726 women died, 657 from CHD. After adjustment for multiple risk factors for CHD and dietary variables, there was an inverse but not statistically significant association between frequent nut consumption (two or more 28.5 g servings per week compared with less than one serving per month) and death from CHD (relative risk 0.81; 95% confidence interval: 0.60-1.11). There was also a weak inverse association between frequent nut intake and all-cause mortality (relative risk 0.88; 95% confidence interval: 0.77-0.99, p for trend = 0.047). CONCLUSIONS: Frequent nut consumption may offer postmenopausal women modest protection against the risk of death from all causes and CHD.
