WATERTOWN — Business is brisk at Fastachi nut shop on Mt. Auburn Street. Almonds and cashews are flying off shelves and nut mixes (often with something sweet like chocolate or dried cranberries, or something hot like wasabi peas) are being scooped by the pound.
According to a recent study, nuts may help us live longer, healthier lives. New research shows that people who eat a daily handful of nuts have improved longevity, lower risk for chronic illnesses like heart disease, and are generally leaner than those who do not eat nuts. The results correlate with an abundance of previous studies. But do the nuts themselves help us live longer, or are they consumed mainly by diligent health enthusiasts dedicated to exercise and eating right in the first place?
The newest research by the Harvard School of Public Health, Brigham and Women's Hospital, and the Dana-Farber Cancer Institute suggests consuming nuts regularly promotes health. Critics say partial funding by a nut research group raises credibility questions.
Souren Etyemezian, who opened Fastachi in 1990 with his wife, Susan, remembers when people thought nuts were too fattening to eat regularly. "People cut them out of their diets," he says, "but now they're back." At large supermarkets, nut selections include bins full of sprouted nuts, organic nuts, and nuts mixed with everything from chocolate to Thai chile peppers. Do-it-yourself trail-mix bars stand beside salad bars; markets are expanding their selections well beyond the small packages of chopped pecans and walnuts once relegated to the baked goods section.
Etyemezian, who will open a second Fastachi location on Charles Street in Boston this year, has noticed changing attitudes. "It started in the early '90s with some of our older and middle-aged customers. They would go see their doctors and come in with a prescription for nuts because their doctors believed in the unsaturated fats."
In the new study, diets of about 119,00 people were analyzed; those who ate about 1 ounce of nuts (a small handful) seven or more times a week were 20 percent less likely to die of any cause during the 30 years they were followed. Even a once-a-week dip into the nut jar resulted in an 11 percent lower incidence of death. Researchers saw similar results for both peanuts, which are actually legumes, and tree nuts such as almonds, cashews, and pecans. The family of tree nuts also includes Brazil nuts, hazelnuts, macadamia nuts, pine nuts, pistachios, walnuts, and others.
Local nutritionists are enthusiastic about the study, but emphasize small portion sizes and a balanced diet as key factors. "We've known for a while that nuts show a benefit, especially for cardiovascular health, but not about the effect on cause-specific and total mortality," says Alicia Romano, clinical dietician at the Frances Stern Nutrition Center at Tufts Medical Center.
Deborah Krivitsky, director of nutrition for the Cardiovascular Disease Prevention Center at Massachusetts General Hospital, says that nuts are a great way to incorporate heart-healthy fats into a balanced diet for their effects on overall health. "It's important that people understand not to be afraid of fats, just include the right types of fats," she says. Krivitsky points out that nuts also offer heart-healthy fiber.
As for the funding, the National Institutes of Health funded the basic research, but partial funding by the International Tree Nut Council Nutrition Research and Education Foundation has raised a few eyebrows. Marion Nestle, New York University professor of nutrition, food studies, sociology, and public health, says that while the researchers involved in this study are superb investigators, industry funding raises credibility questions. Funded studies consistently produce results that benefit the funder, she says, and the tree nut group had a specific purpose: "To be able to say in its marketing that nuts make people healthy."
Lead study author Ying Bao, associate epidemiologist at Brigham and Women's Hospital, says, "The amount that the international nut foundation has put in this study is tiny, tiny when compared to the investment from NIH." Bao, also an instructor in medicine at Harvard Medical School, says that government funding is limited and that NIH encourages exploring alternate sources.
Nestle says that if food companies are interested in funding research, she suggests asking them to contribute to a common kitty to which researchers can apply for grants without knowledge of who provided funding (with a grant committee with no ties to industry). Contributing companies should not know the topics of research, Nestle says.
Few would disagree that nuts are a dense source of nutrition. But the real question is: Do nut eaters tend to have healthy lifestyles in general? While observational studies like this one are not able to pinpoint causality, it is likely that eating nuts has an independent effect on health, according to Walter Willett, professor of epidemiology and nutrition, chair of the department of nutrition at Harvard's School of Public Health, and one of the study's authors. Willett points to the results of the new research in the context of previous research of different types, including controlled feeding studies. "You put all the different kinds of studies together, which all point in the same direction, and that makes a very compelling case that nuts do improve risk of heart disease and other health outcomes and, not surprisingly, overall mortality."
While nut eaters tended to have other healthy habits, both Bao and Willett note that the study statistically adjusted for lifestyle variables related to health. Results indicated that even those who didn't have other healthy habits benefited from a daily handful of nuts. "There was always a consistent inverse association between nuts and mortality," says Bao.
The nutritional profile of nuts as a whole, which includes unsaturated fats, antioxidants, protein, fiber, vitamins, minerals, and phytosterols, may be what's responsible for the protective effects. Willett says, "Like most good things it's a package."
Still, it can be difficult to get used to the idea that the high fat and calories in nuts should be a daily habit. A handful of raw almonds, which is about ¼ cup, contains 207 calories, according to the USDA Nutrient Database (see chart). You would think that eating nuts daily would eventually lead to weight gain.
Actually, studies consistently show the opposite. Nut eaters weigh less and are less likely to become obese. This may seem counterintuitive, but it turns out that nutrients in nuts, like fiber and the good-for-you unsaturated fats that protect against chronic disease, also help prevent overeating. Nuts may help keep people leaner because they are filling, Willet says. "You have a handful of nuts and you just don't feel hungry after that, it really does take away hunger and that turns out to be a very important factor in whether we gain weight or lose weight over the long run."
In other words, sprinkling nuts on morning cereal may just help us forgo those regrettable bad-for-you midmorning snacks. Instead of say, a muffin or doughnut for coffee break, the idea is to keep hunger at bay with a handful of nuts.
No one is recommending the smoky, salty nuts and varieties covered with candy-like flavor enhancers, and adding nuts to a junk food diet will not garner a clean bill of health. Willett cautions against loading up on too many nuts as well. He suggests using them to replace cheese or meat on salads, tossing some into your yogurt, and mixing them with legumes for protein-rich vegetarian dishes.
Not everyone may be willing to eat them as enthusiastically as the famous scientist. Willett's wife makes a nut loaf, which the two eat not as a snack, but as a main course instead of meat or its substitutes.
Nuts as an entree? Gotta love a scientist who practices what he preaches.
Valerie Ryan can be reached at firstname.lastname@example.org.