Sabaté J., D.G. Hook. Almonds, walnuts, and serum lipids. In: Spiller, G.A. Handbook of Lipids in Human Nutrition. New York, NY: CRC Press, Inc.; 1996.
This chapter reviews human studies that look at the effects of whole almonds and walnuts on blood lipid levels. Although each of the studies differ in methodology, the overriding consensus is that almonds, walnuts, and possibly other nuts with a similar nutrient composition, have a cholesterol lowering effect. The protective effect of nuts on coronary heart disease may be due to their fatty acid composition (mostly unsaturated fats) and other components in nuts.
Colquhoun, D.M., J.A. Humphries, D. Moores, S.M. Somerset, 1996. Effects of a macadamia nut enriched diet on serum lipids and lipoproteins compared to a low fat diet. Food Australia. 48(5):216-22.
Macadamia nuts are a native Australian food rich in the monounsaturated fats, oleic acid and palmitoleic acid. A monounsaturated fatty acid-rich diet (MD), enriched with macadamia nuts (40% energy as fat, 20% energy from macadamia nuts) was compared with a high-complex-carbohydrate diet (HC) for effects on serum lipid and lipoprotein levels. Subjects (7 female, 7 male) between 25 and 59 years of age were randomly allocated either to MD followed by HC, or vice versa. Each dietary phase lasted 4 weeks. Both diets lowered serum cholesterol by 7.9% (p<0.01) and low density lipoprotein cholesterol (LDL) by 10.7% (p<0.01) compared with baseline values. The MD led to a 20.9% decrease in serum triglyceride levels (p<0.01). Triglyceride levels were not affected by HC. High density lipoprotein cholesterol (HDL) decreased 13.1% with HC (p<0.05). MD and HC were equally effective in lowering serum cholesterol LDL levels, and MD unlike HC lowered triglyceride levels without affecting HDL levels.
Dreher, M. L., Maher, C. V., Kearney, P. 1996. The traditional and emerging role of nuts in healthful diets. Nutrition Reviews 54:241.
Throughout history, nuts have been a staple food providing energy, protein, essential fatty acids, vitamins, and minerals. Today, nuts are classified as part of the USDA Food Guide Pyramid’s Meat/ Meat Alternate Group. Foods in this group contribute protein as well as important vitamins and minerals to the diet. Nuts are also being studied for their potential health benefits. Research suggests that there may be a connection between frequent nut consumption and a reduced incidence of coronary heart disease. Thus, tradition and promising scientific evidence combine to support the role of nuts in healthful eating.
Sabaté J., G.E. Fraser, 1994. Nuts: a new protective food against coronary heart disease. Current Opinion in Lipidology. 5:11-16.
Recent epidemiological findings indicate that frequent nut consumption offers protection from fatal and non-fatal coronary heart disease events. Although human nutrition studies seem to indicate that nut consumption lowers total and LDL cholesterol, the unique nutrient composition of nuts invites speculation on other mechanisms of protection.
Fraser, G.E., 1994. Diet and coronary heart disease: beyond dietary fats and low-density-lipoprotein cholesterol. Am J Clin Nutr. 59(suppl):1117S-23S.
Traditionally, the effects of diet on coronary heart disease have been attributed to the effects of medium-chain fatty acids, soluble fiber, and dietary cholesterol on serum low-density-lipoprotein (LDL) cholesterol concentrations. We review evidence here that many other dietary substances may affect risk, often via mechanisms not involving LDL-cholesterol concentrations directly. Such substances include phytosterols, tocotrienols, arginine, and antioxidant vitamins. The effects of diet on high-density-lipoprotein-cholesterol concentrations, triglycerides (fasting and postprandial), oxidized LDL particles, prostaglandins, and endothelium-derived relaxing factor are described. Finally, an illustration of some epidemiologic associations between diet and coronary disease events is made from the Adventist Health Study data.
de Lorgeril et al, 1994. Mediterranean alpha-linolenic acid-rich diet in secondary prevention of heart disease. Lancet. 343(8911):1454-9
In a prospective, randomized single-blinded secondary prevention trial we compared the effect of a Mediterranean alpha-linolenic acid-rich diet to the usual post-infarct prudent diet. After a first myocardial infarction, patients were randomly assigned to the experimental (n = 302) or control group (n = 303). Patients were seen again 8 weeks after randomization, and each year for 5 years. The experimental group consumed significantly less lipids, saturated fat, cholesterol, and linoleic acid but more oleic and alpha-linolenic acids confirmed by measurements in plasma. Serum lipids, blood pressure, and body mass index remained similar in the 2 groups. In the experimental group, plasma levels of albumin, vitamin E, and vitamin C were increased, and granulocyte count decreased. After a mean follow up of 27 months, there were 16 cardiac deaths in the control and 3 in the experimental group; 17 non-fatal myocardial infarction in the control and 5 in the experimental groups: a risk ratio for these two main endpoints combined of 0.27 (95% CI 0.12-0.59, p = 0.001) after adjustment for prognostic variables. Overall mortality was 20 in the control, 8 in the experimental group, an adjusted risk ratio of 0.30 (95% CI 0.11-0.82, p = 0.02). An alpha-linolenic acid-rich Mediterranean diet seems to be more efficient than presently used diets in the secondary prevention of coronary events and deat
Abbey, M., M. Noakes, G.B. Belling, P.J. Nestel, 1994. Partial replacement of saturated fatty acids with almonds or walnuts lowers total plasma cholesterol and low-density-lipoprotein cholesterol. Am J Clin Nutr. 59:995-9.
Sixteen normolipidemic male volunteers aged 41 +/- 9 y (mean +/- SD) consumed a diet providing 36% of energy as fat (92 g fat/d) for 9 wk. A daily supplement of nuts (providing half of the total fat intake) was provided against a common background diet. In the first 3-wk period the background diet was supplemented with raw peanuts (50 g/d), coconut cubes (40 g/d), and a coconut confectionary bar (50 g/d), designed to provide 47 g fat with a ratio of polyunsaturated to monounsaturated to saturated fatty acids (P:M:S) to match the Australian diet (reference diet). During the following 3 wk the background diet was supplemented with monounsaturated fatty acid-rich raw almonds (84 g/d), equivalent to 46 g fat, and during the final 3-wk period the background diet was supplemented with polyunsaturated fatty acid-rich walnuts (68 g/d), equivalent to 46 g fat. Compared with the reference diet there were significant reductions in total and LDL cholesterol, 7% and 10%, respectively, after supplementation with almonds, and 5% and 9%, respectively, after supplementation with walnuts.
Sabaté, J., G.E. Fraser, K. Burke, S.F. Knutsen, H. Bennett, K.D. Lindsted, 1993. Effects of walnuts on serum lipid levels and blood pressure in normal men. NEJM. 328(9):603-7.
BACKGROUND: In a recent six-year follow-up study, we found that frequent consumption of nuts was associated with a reduced risk of ischemic heart disease. To explore possible explanations for this finding, we studied the effects of nut consumption on serum lipids and blood pressure. METHODS: We randomly placed 18 healthy men on two mixed natural diets, each diet to be followed for four weeks. Both diets conformed to the National Cholesterol Education Program Step 1 diet and contained identical foods and macronutrients, except that 20 percent of the calories of one diet (the walnut diet) were derived from walnuts (offset by lesser amounts of fatty foods, meat, and visible fat [oils, margarine, and butter]). RESULTS: With the reference diet, the mean (+/- SD) serum values for total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol were, respectively, 182 +/- 23, 112 +/- 16, and 47 +/- 11 mg per deciliter (4.71 +/- 0.59, 2.90 +/- 0.41, and 1.22 +/- 0.28 mmol per liter). With the walnut diet, the mean total cholesterol level was 22.4 mg per deciliter (0.58 mmol per liter) lower than the mean level with the reference diet (95 percent confidence interval, 28 to 17 mg per deciliter [0.72 to 0.44 mmol per liter]); the LDL and HDL cholesterol levels were, respectively, 18.2 mg per deciliter (0.47 mmol per liter) (P < 0.001) and 2.3 mg per deciliter (0.06 mmol per liter) (P = 0.01) lower. These lower values represented reductions of 12.4, 16.3, and 4.9 percent in the levels of total, LDL, and HDL cholesterol, respectively. The ratio of LDL cholesterol to HDL cholesterol was also lowered (P < 0.001) by the walnut diet. Mean blood-pressure values did not change during either dietary period. CONCLUSIONS: Incorporating moderate quantities of walnuts into the recommended cholesterol-lowering diet while maintaining the intake of total dietary fat and calories decreases serum levels of total cholesterol and favorably modifies the lipoprotein profile in normal men. The long-term effects of walnut consumption and the extension of this finding to other population groups deserve further study.
Sabaté, J., 1993. Does nut consumption protect against ischaemic heart disease? Eur J of Clin Nutr. 47(suppl.1):S71-5.
Results of an epidemiological study conducted among California Adventists provides strong evidence that frequent nut consumption has a protective effect on both fatal and non-fatal ischaemic heart disease. It’s plausible, due to the unique composition of nuts, that nuts favorably affect heart disease risk factors and interfere with the process of atherogenesis. Results of human nutritional studies, with varying degrees of methodological rigor all seem to indicate that eating nuts lowers serum cholesterol and favorably modifies the lipoprotein profile.
Klevay, L.M., 1993. Copper in nuts may lower heart disease risk. Arch Intern Med. 153: 401-2.
In this commentary on the Seventh-Day Adventist study, the author discuses the fact that nuts are relatively high in copper and that this may provide protection against a variety of disorders related to atherosclerosis. Copper deficiency is the only nutritional insult that has been shown to produce abnormal electrocardiograms, glucose intolerance, hypercholesterolemia, hypertension, hyperuricemia, injury by free radicals and thrombosis in animals. More than 31 men and women have responded to diets low in copper with potentially harmful changes in glucose tolerance, blood pressure, blood lipids and electrocardiograms. Copper in these daily diets ranged from 0.65 to 1.02 mg amounts. Eating an ounce of nuts can add approximately 0.37 mg of copper to daily intakes.
