Among those who ate nuts less often than once a week, the death rate was 11 percent below those who did not eat nuts.
Regular nut-eaters had a 29 percent reduction in deaths from heart disease - the leading cause of death - and an 11 percent reduction in the risk of dying from cancer.
(Note: while the National Institutes of Health funded most of the study, researchers also received a grant from the International Tree Nut Council Nutrition Research and Education Foundation - which did not affect the results, according to researchers.)
"I'm a big fan of nuts," said Frances Burke, the lead nutritionist for the Penn Med preventive cardiology program. While they are high in fat and calories, she points out that the difference with nuts is that "saturated fat or animal fat increases the risk of heart disease, while nuts are high in mono- and polyunsaturated fats, fiber, and plant sterols, which prevent absorption of cholesterol." They also provide antioxidants, fiber, and many phytochemicals and micronutrients.
The New England Journal report also found that while nuts are high-calorie foods, the nut-eaters were less likely to be obese than those who did not eat nuts.
This finding echoes those of earlier studies and is reinforced by a new 2014 paper from Loma Linda University showing that Seventh-day Adventists who ate the most tree nuts - almonds, Brazil nuts, pistachios, and walnuts - were between 37 and 46 percent less likely to be obese than those who consumed the fewest tree nuts.
"Those choosing to eat nuts frequently have less risk of developing metabolic syndrome and of becoming obese," said lead author Joan Sabaté, chair of Loma Linda's department of nutrition. "Eating nuts is frequently associated with a lean body."
How can this be? There are several theories. "Eating nuts is not associated with obesity because they provide more satiety, and all the energy/fat in nuts is not fully absorbed by the body," Sabaté said.
In addition, the New England Journal study points out that nut-eaters may have a generally healthier lifestyle than non-nut-eaters.
Sabaté has been examining the benefits of nuts since 1993, when he published a study in the New England Journal showing that nuts raise good cholesterol and lower bad cholesterol.
He is currently conducting the Walnuts and Health Aging Study, which will examine the effect of walnuts on cognition and eye health.
Another recent study shows that consuming whole walnuts or their extracted oil reduces cardiovascular risk through a mechanism other than simply lowering cholesterol, according to a team of researchers from Penn State, Tufts University, and the University of Pennsylvania. Results showed that consumption of whole walnuts helped HDL - good cholesterol - perform more effectively in transporting and removing excess cholesterol from the body.
Penny Kris-Etherton, a professor of nutrition at Pennsylvania State University and lead author of the study, points out that while nuts are beneficial, the benefits will not be reaped by those who eat an unhealthy diet and then sit down to devour a can of salted nuts.
"Adding nuts to your donuts won't help," she said.
But judiciously adding nuts to a healthy diet can make a difference. She suggests eating nuts with meals, rather than snacking on them, and buying them in small quantities, to prevent overeating them. To get the most benefit, she suggests that people eat mixed nuts, at least five times a week.
"Eat nuts regularly in small quantities. Ideally use nuts to replace other high-fat protein food from animal origins," said Sabaté, who points out that it's not clear if tree nuts offer more benefits than peanuts, which are technically legumes.
"When I counsel people, I tell them to include protein with most meals and to keep it low-carb. The problem with carbohydrates is that that they are absorbed very quickly and leave you hungry," Burke said. "Nuts are high in protein and fat - fat gives you sustainability. Something with protein, such as peanut butter or hummus with olive oil, tends to be more sustainable. Nuts get me to the next meal and I don't find myself hungry in between times.
"As long as people don't have nut allergies and like nuts, I find that if people can maintain their weight, nuts can be a part of a heart-healthy diet."
Soup to Nuts
It's easy to overindulge with nuts. To prevent this, experts suggest adding them to foods as part of your regular diet. Possibilities suggested by Andrew Schloss, author of Cooking Slow, include:
- Adding nuts to hot or cold breakfast cereals.
- Replacing 25 to 30 percent of flour in baked goods with ground nuts.
- Using ground nuts as a thickening agent in soups and chilis.
- Sprinkling nuts over salads.
- Using them in stir-fries.
- Adding toasted pine nuts to soups or stews.
- Mixing a gremolata with chopped parsley, nuts, and citrus zest to use as a garnish for meat dishes.