Eating a small amount of nuts each day may help people live longer, a new study suggests.
In the study, which included information from more than 118,000 people, those who ate about 1 ounce (28 grams) of nuts daily, seven days a week, were 20 percent less likely to die over a 30-year period compared with those who did not consume nuts.
When the researchers looked at specific causes of death, they found that people who ate a daily ounce of nuts were 29 percent less likely to die of heart disease, 24 percent less likely to die from respiratory disease and 11 percent less likely to die from cancer, according to study, published in the Nov. 21 issue of the New England Journal of Medicine.
The link between nut consumption and longer life held even after the researchers took into account factors that might affect people's life span, such as their weight, physical activity, and fruit and vegetable consumption. [9 Snack Foods: Healthy or Not?]
The study is one of the largest to look at the link between nut consumption and overall risk of death, the researchers said. The work was funded, in part, by the International Tree Nut Council Nutrition Research & Education Foundation, which had no role in the study design or interpretation of the data.
"The findings from our study and others suggest a potential benefit of nut consumption for promoting health and longevity," study researcher Dr. Charles Fuchs, of the Dana-Farber Cancer Institute in Boston, said in a statement.
Nuts are rich in vitamins, minerals, unsaturated fatty acids and antioxidants, and are a source of protein. But nuts are also high in calories, so people should be careful not to eat too many. The American Heart Association recommends eating four 1.5-ounce (about a handful) servings of unsalted, unoiled nuts per week, and the U.S. Food and Drug Administration says that eating 1.5 ounces of nuts per day may reduce the risk of heart disease.
The researchers analyzed information from more than 76,000 female nurses and more than 42,000 male physicians from the 1980s to 2010. Every two to four years, participants were asked about their typical food intake, including how often they consumed nuts.
During the study period, 16,200 women and 11,229 men died.
Eating nuts less often than daily was also linked with a reduced risk of death, but the link was not as strong: People who ate nuts two to four times a week were 13 percent less likely to die during the study period, those who ate nuts once a week had a 11 percent reduced risk of death and those who ate nuts less than once a week were 7 percent less likely to die during the study period.
The findings were similar for consumption of peanuts as well as tree nuts, including walnuts, hazelnuts and almonds.
Still, the study does not prove that eating nuts was the cause of people's longer lives; it's possible that another factor not accounted for by the researchers was responsible for increased life span, or that people who are in poor health to begin with tend to not eat nuts.
However, people with a history of cancer, heart disease or stroke were not included in the study. The findings support the results of prior research linking nut consumption with a reduced risk of many diseases, including heart disease, type 2 diabetes and colon cancer.
Dr. Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York who was not involved in the study, said the findings reaffirm the known benefits of nuts.
"It's really such a powerful thing to know — that I can eat nuts as part of my diet, and it can actually have a positive outcome on health," Steinbaum told LiveScience. "It's really such a cardio-protective food."
The study relied on people's self-reports of what they were eating, which may not always be accurate. But another study found this method of collection was reasonably accurate.