Good News, Nut Lovers
Reviewed By Gary Vogin
Nuts? No thanks, many of us have learned to say, with a pang of regret.
Nuts, after all, get more than half of their calories from fat. That's more than whole milk, ground beef, even cheese. All that fat not only threatens to make us fat, nutritionists have warned, it also raises our risk of heart disease.
Well, nut lovers, take heart. The bad rap nuts have gotten is more than just unfair, it's downright slanderous. Eating plenty of nuts, it turns out, may actually lower heart disease risk. And far from adding pounds, a diet with nuts may be a good way to maintain a healthy weight.
In the November 1998 issue of the British Medical Journal, Harvard School of Public Health researchers reported findings from the Nurses' Health Study, which includes more than 86,000 women from around the country. Women who ate more than five ounces of nuts a day, the scientists found, had a 32% lower risk of having a nonfatal heart attack compared to women who avoided nuts. Their risk of a fatal heart attack was 39% lower than that of women who rarely munched a pecan or cashew.
True, women who helped themselves to nuts also tended to have healthier lifestyles, says Frank Hu, MD, PhD, the lead researcher on the study. "But even when we adjusted for factors like smoking, exercise, and consumption of fruits and vegetables," he says, "nuts showed up as a powerful defense against heart disease."
The Harvard study isn't the first to link nuts to lower heart disease risk. In a study published in the July 1992 issue of the Archives of Internal Medicine, researchers from Loma Linda, sifting through data from 34,000 men and women in what's known as the Seventh Day Adventist Study, found that nut eaters were half as likely as those who didn't eat nuts to suffer both fatal and nonfatal heart attacks. Four years later, in findings published in The New England Journal of Medicine in 1996, scientists showed that eating nuts was associated with a 40% reduction in heart disease risk among women enrolled in the Iowa Women's Study.
How can a food so high in fat be good for your heart? Part of the answer has to do with the kind of fat nuts contain. The real danger to heart and arteries is posed by saturated fats, which show up mostly in meat and high-fat dairy products like cheese, cream, and whole milk. The fat in most nuts, in contrast, is unsaturated. Cashews, almonds, and peanuts are loaded with monounsaturated fats, and walnuts are rich in a form of omega 3 fatty acids, polyunsaturated fats similar to the oils found in fish like salmon.
"Monounsaturated and polyunsaturated fats have been shown to lower LDLs [low density lipoproteins], or so-called bad cholesterol," says Hu.
Nearly a dozen controlled studies have shown that when volunteers add nuts to their diets, their level of these low-density lipoproteins, which can gum up blood vessels and increase the danger of coronary artery disease, declines by as much as 12%.
Nuts pack plenty of other nutritional benefits. They're high in fiber, which has been shown to help keep cholesterol levels down. And they're loaded with the antioxidant vitamin E, which is linked in some studies to a lower risk of heart disease. Nuts, in fact, are "perhaps the best natural source of vitamin E," wrote Loma Linda University scientists in a study published in the July 1999 issue of Clinical Cardiology.
Nutritionists also have long known that nuts are a great source of protein. Indeed, the protein in nuts is unusually rich in an amino acid called arginine, which may also be linked to its heart benefits. Arginine makes possible the synthesis of nitric oxide, which widens and relaxes blood vessels according to Gene Spiller, PhD, founder of the Health Research and Studies Center in Palo Alto, Calif., and the author of Healthy Nuts. That, in turn, may reduce the danger of blood clots that can lead to heart attacks.
Nuts may even have something in common with red wine, which, consumed in moderation, has also been shown to lower heart disease risk. Last year, researchers from the U.S. Department of Agriculture in Raleigh, N.C., announced that peanuts contain resveratrol, the same compound found in red wine that is thought to impart much of its heart benefits. An ounce of red wine contains about 160 micrograms of resveratrol; two ounces of peanuts contain about the same amount.
The New Diet Snack
The latest findings offer one last surprise, and perhaps the best news of all for nut lovers. Despite being high in fat, cashews, almonds, pecans, and other nuts don't seem to make people fat. When volunteers in the Loma Linda study added a snack of almonds totaling 320 calories a day to their normal diets, for example, their body weight remained the same. Furthermore, in the Nurses' Health Study, Hu and his colleagues found that women who ate nuts frequently actually tended to weigh less than those who didn't.
Why, of course, is anyone's guess. "But one reason may be that nuts are so rich in nutrients and fiber that they tend to fill people up on fewer calories than, say, a bag of chips or cheese doodles," says Spiller.
If you're watching your weight, in other words, a handful of nuts is a terrific substitute for less nutritious and less satisfying snacks. And thanks to the latest research findings, you can enjoy them with hardly a pang of regret.
Peter Jaret is a freelance writer in Petaluma, Calif., who has written for Health, Hippocrates, and many other national publications.Originally published March 26, 2001.
Updated and medically reviewed on March 22, 2002.