There is another reason besides flavor and crunch for nut lovers to eat nuts: they are heart healthy. In July 2003, the Food and Drug Administration approved a qualified health claim that states, “Scientific evidence suggests, but does not prove that eating 1.5 ounces per day of most nuts, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.” This approval (www.cfsan.fda.gov/~dms/qhcnuts2.html) was in response to a petition filed by the International Tree Nut Council’s Nutrition Research and Education Foundation.
The qualified heart health claim is based on several studies showing that people who eat nuts regularly cut their risk of heart disease, sometimes by as much as half. Other studies have shown that consuming 1–3 oz/day of some nuts can lower elevated blood cholesterol, as well as other substances in the blood that have been linked to heart disease. Nuts’ high monounsaturated and polyunsaturated fatty acid content is one reason for their heart-health benefits.
The qualified health claim does not include all nuts, because some have higher levels of saturated fat. Here’s a rundown of the nuts included in the claim—almonds, hazelnuts, peanuts, pecans, pistachios, and walnuts—and some of their reported health benefits.
According to the Almond Board of California, almonds are a leading source of vitamin E and magnesium and offer protein, fiber, potassium, calcium, phosphorus, and iron; 1.5 oz provides 246 kcal.
The following recent studies have shown that almonds can help in increasing vitamin E intake, lowering cholesterol, and aiding in weight loss.
• Increasing Vitamin E Intake. The Recommended Daily Allowance (RDA) for vitamin E is 15 mg. Americans are only consuming half of this, according to the National Academy of Science. In September 2003, the U.S. Dept. of Agriculture proposed food intake patterns of 1,000 to 3,200 kcal, that provide 44% to 92% of the RDA for vitamin E, respectively.
Although the current Food Guide Pyramid does not readily direct consumers to vitamin E–rich foods, eating 1 oz of almonds (160 kcal) would provide 7.3 mg of alpha-tocopherol vitamin E, which would close the vitamin E gap, says the Almond Board of California. About 98% of the vitamin E in almonds is alpha-tocopherol.
• Lowering Cholesterol. Almonds were part of a dietary approach that was found to be as effective as the starting dose of cholesterol-lowering drugs such as statins in managing cholesterol (Jenkins et al., 2003). Known as the “Portfolio” eating plan, the dietary approach also lowered c-reactive protein levels—an indicator of inflamed arteries and a risk factor for heart disease—in individuals who followed the plan more than in the patients taking statins.
Almonds were the only nut included in the eating plan, which also included foods high in soy protein, viscous fiber, and plant sterols, said study leader David Jenkins of the Clinical Nutrition and Risk Factor Modification Center at St. Michael’s Hospital in Toronto and the University of Toronto’s Dept. of Nutritional Sciences. The eating plan was designed to be a heart-healthy, low-saturated-fat diet.
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Patients ate a daily handful of almonds, which Cyril Kendall, a research scientist on the team, calls a “mini-Port-folio” because of their vegetable protein, plant sterols, and fiber, as well as their overall nutrient density. Almonds, with their high vitamin E content, may have been a factor in decreasing the Portfolio subjects’ c-reactive protein levels.
• Aiding Weight Loss. A moderate-fat almond diet resulted in greater weight loss than a lowfat diet containing the same daily calories (Wien et al., 2003). In this study, 65 overweight and obese adults—70% of whom had type 2 diabetes—were put on one of two diets designed for weight loss. The first group ate a liquid formula–based low-calorie diet containing moderate fat from almonds (39% total fat, 25% monounsaturated fat, and 35% carbohydrate as percent of energy). The second group ate a liquid formula–based low-fat, low-calorie diet including self-selected complex carbohydrates (18% total fat, 5% monounsaturated fat, and 53% carbohydrate as percent of energy). The two diets’ calorie count and protein levels were equivalent.
After 24 weeks, patients on the moderate-fat diet containing almonds had achieved a greater reduction in weight, waist circumference, fat mass, and systolic blood pressure than those on the lowfat diet. Both groups experienced lower glucose and insulin levels, but medication requirements for individuals with type 2 diabetes decreased more steadily in the low-calorie almond diet than the low-calorie complex carbohydrate diet.
“There may be qualities in almonds that helped the first group lose more weight,” said Michelle Wien, the study’s lead researcher at City of Hope National Medical Center in Duarte, Calif. One possible explanation for the effects observed in Wien’s study is that the fat in almonds may not have been completely absorbed.
Hazelnuts are also rich in vitamin E and contain less than 4% saturated fat and 5.81% polyunsaturated fat. The majority of the fat is monounsaturated (90.71%), mostly oleic acid. A 1-oz serving (28–30 nuts) contributes 178 kcal.
Research has shown that hazelnuts can successfully be used in a lowfat dairy beverage and nutrition bar. The Hazelnut Council provides two technical overviews for using hazelnuts in these products (www.hazelnutcouncil.org/commercial/research.html).
Scientists at Michigan State University used hazelnut meal to fortify a lowfat dairy-based beverage (www.hazelnutcouncil.org/commercial/dairy-monograph.html). Six hazelnut formulas were developed in caramel, caramel–coffee, and caramel–coffee–chocolate flavor blends. Sensory results showed that coffee and caramel flavor combined with hazelnut significantly improved the overall liking and acceptability of lowfat dairy beverages. Hazelnut provided essential fatty acids, calcium, and vitamin E.
At Colorado State University, researchers developed 23 different nutrition bar prototypes, containing hazelnut in different forms and levels (www.hazelnutcouncil.org/commercial/nutrition-monograph.html). In sensory tests, the hazelnut bars were highly rated, scoring in the top-third of the scoring scale for overall acceptability and rated highly for appearance, aroma, texture, and flavor. Hazelnuts provided a means to create nutrition bars that were low in fat, high in complex carbohydrates, and low in sodium.
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Peanuts provide 2 g of fiber/oz and are a source of essential minerals, vitamin E, and B vitamins such as folate. Recent studies have shown peanuts’ benefits for cardiovascular health and type 2 diabetes.
• Cardiovascular Health. Alper and Mattes (2003) at Purdue University showed that regular consumption of peanuts lowered triglycerides and improved total diet quality by increasing nutrients associated with the prevention of cardiovascular disease, including magnesium, folate, vitamin E, copper, arginine, and fiber. The researchers studied the effects of chronic peanut consumption on well-known risk factors for cardiovascular disease.
One of the principle investigators, Richard Mattes of Purdue’s Dept. of Foods and Nutrition, said, “We wanted to determine the impact of peanut consumption on total diet quality. We found that including peanuts in the diet significantly increased magnesium, folate, fiber, copper, vitamin E, and arginine consumption, all of which play a role in the prevention of heart disease.”
These findings are consistent with several clinical and epidemiological studies, such as the Nurses’ Health Study, that show that people who consume about 1 oz of peanuts, nuts, and peanut butter per day improve blood lipid levels and decrease risk of cardiovascular disease.
The Purdue study included 15 healthy men and women who were each put on three different daily diets that included approximately 500 kcal of peanuts: (1) a free-feeding diet, which involved including 500 kcal of peanuts without any dietary guidance; (2) an addition treatment which entailed adding 500 kcal of peanuts to each participant’s usual diet; and (3) a substitution treatment in which participants substituted peanuts for 500 kcal from fat in their usual diet.
Throughout the study, peanut consumption led to favorable changes in the fat profile of the diet—saturated fat decreased and unsaturated fat increased as a portion of calories.
• Type 2 Diabetes. Jiang et al. (2002) at the Harvard School of Public Health reported that consuming a half-serving (1 tbsp) of peanut butter or a full serving of peanuts or other nuts (1 oz) five or more times a week was associated with a 20% or 30% reduced risk of developing type 2 diabetes, respectively.
The study showed that women who ate 5 tbsp of peanut butter each week reduced their risk of developing type 2 diabetes by almost 20%. Furthermore, the relationship between consuming peanut butter, peanuts, and other nuts and type 2 diabetes was linear—higher consumption provided a greater protective effect. The group of women consuming a half-serving of peanut butter or a full serving of peanuts and other nuts 1–4 times/week had a 16% reduced risk of developing the disease.
The large population study included more than 83,000 female nurses who were followed for an average of 16 years in the Brigham and Women’s Hospital-based Nurses’ Health Study. The women in the study completed food-frequency questionnaires approximately every four years between 1980 and 1996, and had no history of diabetes, cardiovascular disease, or cancer.
Frank Hu, Associate Professor of Nutrition and Epidemiology at the Harvard School of Public Health and an author of the study, said, “Given the observed inverse association between nuts and risk of coronary heart disease as well as type 2 diabetes, it is advisable to recommend regular peanut butter and nut consumption as a replacement for refined grain products or red or processed meats, which would avoid increasing caloric intake.”
Pecans contain more than 19 vitamins and minerals, including vitamin A, E, folic acid, calcium, magnesium, phosphorus, potassium, several B vitamins, and zinc. About 60% of the fat in pecans is monounsaturated and another 30% is polyunsaturated. In addition, 1 oz of pecans provides 10% of the recommended Daily Value (DV) for fiber. Studies show that in addition to lowering cholesterol, pecans also support intestinal health and increase nutrient and fiber intake.
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• Intestinal Health. Morgan and Clayshulte (2000) at New Mexico State University looked at supplementing the diet of 19 men and women with normal blood lipid levels with 3/4 cup of pecans/day. The researchers observed that adding pecans to a self-selected diet lowered low-density lipoprotein (LDL) cholesterol levels by 6%, and total cholesterol levels were lower as well. Further analysis revealed that the pecan-enriched diet significantly raised blood levels of gamma-tocopherol, a unique form of vitamin E. Studies have shown that this antioxidant may benefit intestinal health and have a protective effect against prostate cancer.
• Fiber Intake. Information presented at a May 2001 American Heart Association conference on Arteriosclerosis, Thrombosis and Vascular Biology showed that a heart-healthy diet containing pecans helped control specific biomarkers of heart disease risk as effectively as AHA’s Step I diet. (Chenault, 2001). In this study, researchers at Texas A&M University also found that the pecan-rich diet significantly increased participants’ levels of dietary fiber, thiamin, magnesium, copper, and manganese and actually changed copper and magnesium intakes from inadequate (on the AHA diet) to adequate (on the pecan diet). All of the participants had already been eating a relatively lowfat diet. For this study, they were placed on either the Step I diet or a higher-fat, pecan-based diet.
A 1-oz serving of pistachios (approximately 47 nuts) contains more than 10% of the DV for dietary fiber, and provides vitamin B-6, thiamin, phosphorus, and copper, according to the California Pistachio Commission. Pistachios contain predominantly monounsaturated fat and 1.5 g of saturated fat per 1-oz serving.
Information presented at the 2001 Experimental Biology annual conference (http://pistachios.org/TopNews.asp?i=58) showed that eating two 1-oz servings of pistachios a day can help adults lower cholesterol. The study, conducted at Inova Fairfax Hospital in Virginia, showed that in people with a moderately high total cholesterol level (>250 mg/dL), the substitution of pistachios for other snack foods (20% of caloric intake) significantly lowered their total cholesterol and LDL cholesterol levels by nearly 10%.
“This study helps debunk the myth that nuts cannot be a part of a heart-healthy eating plan,” said Kathy McMahon, nutrition consultant to the California Pistachio Commission. “In fact, pistachios can fit well within dietary recommendations for heart-healthy eating, while delivering satisfying, great taste.”
In addition to the qualified health claim for all of the above nuts, walnuts also received approval for a qualified heart health claim specific to whole or chopped walnuts (www.cfsan.fda.gov/~dms/qhcnuts.html). The wording is similar, but this claim was petitioned by the California Walnut Commission.
Many studies have linked walnuts to benefiting cardiovascular health. A scientific review of five controlled, peer-reviewed, human clinical walnut-intervention trials was published (Feldman, 2002). Key findings suggested that consuming walnuts did not cause a net gain in body weight, walnuts decreased serum cholesterol and reduced relative risk for heart disease by 30–50%, and walnuts are unique among nuts because of their polyunsaturated fat (omega-3 and omega-6 fatty acid) content.
Walnuts also contain other important vitamins, such as vitamin E, minerals, protein, and antioxidants. According to the Walnut Marketing Board, 1.5 oz of walnuts more than fulfills the daily requirement for essential omega-3 fatty acids.
So in a nutshell, nuts are a powerhouse of nutrients.
Almond Board of California www.almondsarein.com
California Pistachio Commission www.pistachios.org
Hazelnut Council www.hazelnutcouncil.org
International Tree Nut Council http://inc.treenuts.org/
International Nut Council www.nuthealth.org
National Pecan Shellers Association www.ilovepecans.org
Peanut Institute www.peanut-institute.org
Walnut Marketing Board www.walnut.org
by LINDA MILO OHR
E-mail: [email protected]
Alper, C.M. and Mattes, R.D. 2003. Peanut consumption improves indices of cardiovascular disease risk in healthy adults. J. Am. College Nutr. 22(2): 133-141.
Chenault, E.A. 2001. Research: Pecan-rich diet as effective as lower-fat AHA diet. AgNews. Texas A&M University Agriculture Program. http://agnews.tamu.edu/stories/HORT/May1201a.htm.
Feldman, E.B. 2002. The scientific evidence for a beneficial health relationship between walnuts and coronary heart disease. J. Nutr. 132: 1062S-1101S.
Jenkins, D.J.A., Kendall, C.W.C., Marchie, A., Faulkner, D.A., Wong, J.M.W., de Souza, R., Emam, A., Parker, T.L., Vidgen, E., Lapsley, K.G., Trautwein, E.A., Josse, R.G., Leiter, L.A., and Connelly, P.W. 2003. Effects of a dietary portfolio of cholesterol-lowering foods vs. Lovastatin on serum lipids and c-reactive protein. J. Am. Med. Assn. 290: 502-510.
Jiang, R., Manson, J.E., Stampfer, M.J., Liu, S., Willett, W.C., and Hu, F.B. 2002. Nut and peanut butter consumption and risk of type 2 diabetes in women. J. Am. Med. Assn. 288: 2554-2560.
Morgan, W.A. and Clayshulte, B.J. 2000. Pecans lower low-density lipoprotein cholesterol in people with normal lipid levels. J. Am. Dietetic Assn. 100(3): 312-318.
USDA. 2003. Nutritional value of nuts. National Nutrient Database for Standard Reference, Release 16. U.S. Dept. of Agriculture, Beltsville, MD.
Wien, M.A., Sabate, J.M., Ikle, D.N., and Kandeel, F.R. 2003. Almonds vs. complex carbohydrates in a weight reduction program. Intl. J. Obesity 27: 1365-1372.