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What Is the Story on Nuts and Health?

Scientists suspect there is a connection between nuts and health. Many studies show nut eaters have less heart disease, strokes or cancer.
What Is the Story on Nuts and Health?

Nuts are not the dietary demons doctors once thought. There was a time when we were warned to stay away from nuts because they are high in both fat and calories. But nutrition researchers have found evidence on nuts and health that reverses that advice.

Pistachios to Lower Bad Blood Fats:

Our readers sometimes make observations about the link between nuts and health that are corroborated by research. Here’s one fascinating story.

Q. I started eating pistachios daily about six months ago. My last blood work for cholesterol showed my triglycerides to be normal for the first time ever! I couldn’t figure out why the sudden drop until I realized that eating pistachios was the only change I’d made.

A. Nutrition studies have found the same effect of eating pistachios. A meta-analysis of 34 trials found that a pistachio-enriched diet lowers triglycerides as well as total and LDL cholesterol (American Journal of Clinical Nutrition, Jan. 1, 2020).  Other nuts, including walnuts and almonds, are also beneficial, but pistachios are the stars.

A Review of Science on Nuts and Health:

An earlier review of 20 studies concluded that people who eat more nuts are less likely to have heart disease, strokes or cancer (BMC Medicine, Dec. 5, 2016). They are also less prone to premature death from lung disease, infections and diabetes. Those who ate about an ounce of nuts daily were 29 percent less likely to have coronary heart disease. They were also 21 percent less likely to have any type of cardiovascular complications.

A drawback of this analysis is that none of these studies were randomized controlled trials. Experiments have shown, though, that nut consumption lowers triglycerides and cholesterol in the bloodstream. In this analysis. peanuts are associated with similar benefits as tree nuts. The study does not demonstrate a cause-and-effect relationship between nuts and health.

Previous Research on the Health Consequences of Eating Nuts:

For years, dietary dogma warned against lots of delicious foods. People were supposed to eat brown rice and broccoli and avoid steak, chocolate and nuts. But the nutrition nay-sayers might consider eating crow, if not steak.

The Mediterranean Diet and Nuts:

While most of the attention to the PREDIMED study of the Mediterranean diet focused on olive oil, one-third of the participants were eating nuts. They did as well as those getting extra olive oil (New England Journal of Medicine, June 21, 2018). The nuts these volunteers ate were hazelnuts, almonds and walnuts.

Physicians and Nurses in Studies:

Walter Willett, MD, PhD, was previously chairman of the Department of Nutrition at Harvard University’s T.H. Chan School of Public Health. Dr. Willett is a fan of nuts. Many years ago, he and his colleagues published a major study (JAMA, Nov. 27, 2002) showing that women who eat 5 ounces or so of nuts or peanut butter a week lower their risk of type 2 diabetes by 27 percent.

That wasn’t the only study demonstrating a connection between nuts and health. Another study showed that a diet rich in almonds lowers cholesterol without raising blood sugar in people with diabetes (American Journal of Clinical Nutrition, Nov. 2002).

Which Nuts Will You Eat?

Other studies have demonstrated a 30 to 50 percent drop in heart disease among people who eat 5 ounces of nuts a week. Almonds, hazelnuts, macadamia nuts, pistachios and peanuts are all rich in good monounsaturated fats, but walnuts, which contain polyunsaturated fats, may be especially beneficial. The omega-3 fatty acids in walnuts are related to those found in fish oil.

Several years ago, we answered this question about selecting nuts:

Q. Could you talk about the relative benefits of various nuts? We know almonds and walnuts can lower cholesterol. Do pecans, macadamia nuts, Brazil nuts or hazelnuts offer anything besides calories?

A. Nearly all nuts have beneficial fatty acids, particularly monounsaturated fatty acids like those found in olive oil. In addition, walnuts contain some omega-3 fatty acids like those found in fish oil.

People who eat five ounces of nuts weekly are less susceptible to heart disease and type-2 diabetes. People who consume Brazil nuts get selenium, which can reduce the risk of osteoarthritis.

Be careful with Brazil nuts, however. They are so rich in this mineral that eating more than three or four a day on a regular basis could result in selenium toxicity (hair loss, rash, nasty nails and nerve damage).

Walnuts and Blood Fats:

Research indicates that these fats can improve the cholesterol profile. A Japanese study years ago showed that women eating walnuts lower their LDL cholesterol levels (European Journal of Clinical Nutrition, July, 2002). Another study found that people consuming walnuts have better ratios of HDL to total cholesterol (Diabetes Care, Nov., 2004). There is a consistent pattern of lower cholesterol for people who eat walnuts (American Journal of Clinical Nutrition, July, 2009).

The omega-3 fats in walnuts also appear to have anti-inflammatory properties. (Other nuts also seem to fight inflammation.) Inflammation is gaining prominence as an important factor in heart disease as well as possibly contributing to Alzheimer’s disease and cancer.

Nuts and the Heart:

Omega-3 fats may also stabilize heart rhythms. The Physicians Health Study has followed 22,000 male doctors for nearly 20 years. Those who rarely ate nuts were about 50 percent more likely to drop dead suddenly of cardiac arrest (Archives of Internal Medicine, June 24, 2002). (That is relative risk.) Presumably, the men consuming nuts at least twice a week were protected from the changes in heart rhythm that are associated with sudden death.

Nuts and Weight Control:

Of course, over-indulging in nuts could lead to weight gain. Walnuts have 185 calories in an ounce. But if you substitute nuts for other foods, especially carbohydrates like bread, bagels, crackers or cookies, you can maintain your waistline, reduce your risk of diabetes and keep your heart healthy. In fact, people who count their calories but include almonds in their diets lower blood pressure better and lose more belly fat compared to dieters who are not consuming nuts (Journal of Nutrition, online, Nov. 2, 2016).

We count many nuts, including almonds and walnuts, among our favorite (healthful) foods. You can learn more about those in our book, The People’s Pharmacy Quick & Handy Home Remedies.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
Citations
  • Liu K et al, "Comparative effects of different types of tree nut consumption on blood lipids: A network meta-analysis of clinical trials." American Journal of Clinical Nutrition, Jan. 1, 2020. DOI: 10.1093/ajcn/nqz280
  • Aune D et al, "Nut consumption and risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective studies." BMC Medicine, Dec. 5, 2016. https://doi.org/10.1186/s12916-016-0730-3
  • Estruch R et al, "Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts." New England Journal of Medicine, June 21, 2018. DOI: 10.1056/NEJMoa1800389
  • Lovejoy JC et al, "Effect of diets enriched in almonds on insulin action and serum lipids in adults with normal glucose tolerance or type 2 diabetes." American Journal of Clinical Nutrition, Nov. 2002. DOI: 10.1093/ajcn/76.5.1000
  • Iwamoto M et al, "Serum lipid profiles in Japanese women and men during consumption of walnuts." European Journal of Clinical Nutrition, July, 2002. DOI: 10.1038/sj.ejcn.1601400
  • Tapsell LC et al, "Including walnuts in a low-fat/modified-fat diet improves HDL cholesterol-to-total cholesterol ratios in patients with type 2 diabetes." Diabetes Care, Nov., 2004. DOI: 10.2337/diacare.27.12.2777
  • Banel DK & Hu FB, "Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review." American Journal of Clinical Nutrition, July, 2009. DOI: 10.3945/ajcn.2009.27457
  • Albert CM et al, "Nut consumption and decreased risk of sudden cardiac death in the Physicians' Health Study." Archives of Internal Medicine, June 24, 2002. DOI: 10.1001/archinte.162.12.1382
  • Dhillon J et al, "Almond consumption during energy restriction lowers truncal fat and blood pressure in compliant overweight or obese adults." Journal of Nutrition, online, Nov. 2, 2016. DOI: 10.3945/jn.116.238444
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