New Harvard research provides the strongest evidence to date that eating nuts can reduce a person’s risk of dying from cancer, heart disease, and a number of other causes.
The study, published Wednesday in the prestigious New England Journal of Medicine, involved more than 118,000 healthy volunteers and found that those who regularly consumed a one-ounce daily serving of walnuts, almonds, cashews or other tree nuts had a 20 percent lower risk of dying from any cause during the three-decade long study compared to those who did not eat nuts.
Nut eaters were 25 percent less likely to die from heart disease, 10 percent less likely to die from cancer, and 20 percent less likely to die from diabetes as well as lung diseases. The study found that nut eaters enjoyed longer lifespans even if they did not exercise, avoided fruits and vegetables, and were overweight.
“The reduction in mortality was substantial,” said senior study author Dr. Charles S. Fuchs, an oncologist at the Dana-Farber Cancer Institute and a Harvard Medical School professor. “I think eating nuts is comparable to other potentially beneficial lifestyle measures like exercise and avoiding obesity and trans fats.”
Nutritionists who weren’t involved in the study expressed enthusiasm over the strong results and the careful study design, but they questioned the researchers’ decision to get partial funding from a foundation that represents tree nut suppliers.
While New York University nutrition professor Marion Nestle said the results confirm the nutritious value of nuts, she roundly criticized the researchers’ acceptance of $150,000 from the International Tree Nut Council Nutrition Research and Education Foundation—which, according to the group’s website, is “a nonprofit organization that represents nine tree nut industries.”
“These are excellent investigators but the funding source casts doubt on the credibility of the science,” Nestle said. “I just don’t think food manufacturers should sponsor research about products they sell. It muddies the water.”
The Boston-based New England Journal of Medicine requires study authors to disclose their sources of financial support and any role industry representatives may have played in the study design or authorship of the paper, according to editor-in-chief Dr. Jeffrey Drazen. “We don’t ignore the funding source but it’s actually not one of major issues in our decision-making process,” he said in an interview. “We try to find the best science possible.”
The study, which also involved researchers from Brigham and Women’s Hospital and Harvard School of Public Health, had limitations: It was an epidemiological study, which passively follow large populations of people to tease out what might make some groups healthier than others. The research couldn’t entirely rule out other factors that could have contributed to the better outcomes for nut eaters, though the researchers said they tried to take into account factors such as partipants’ dietary habits, smoking status, and physical activity level.
“People who eat nuts have healthier lifestyles and may take the stairs instead of an elevator or work out harder at the gym,” Drazen said.
Thus, it was impossible for the researchers to conclude with certainty that one particular lifestyle component—such as eating nuts—led to longer lives.
Based on the new research, “if you think adding almonds or walnuts to a lifestyle of sloth and gluttony will help you live longer,” Drazen said, “you’re probably nuts.”
The study, however, is backed by a long line of previous studies that also suggest eating nuts confers health benefits. A decade ago, the US Food and Drug Administration determined that there was enough evidence to announce to Americans that eating 1.5 ounces of nuts each day “may reduce the risk of heart disease.”
Peanuts—which are technically legumes—are included in this group, though the new research found that they were slightly less protective than tree nuts.
“I’m fairly confident in our results,” said Dr. Ying Bao, a Brigham epidemiologist who led the study. “We have long known that nuts are nutritious foods filled with folate, potassium, fiber, good monounsaturated fats, and antioxidants.”
She said she applied for and received a two-year grant from the tree nut council’s foundation last year to supplement long-term funding from the National Institutes of Health, which has gotten skimpier with its grants since the recession.
Bao said that the researchers submitted the manuscript to the nut council foundation before they sent it off to the journal, but that they didn’t solicit nor receive comments on their research or the article from the council.
Bao did not, however, consider the nut council foundation to be an industry group. “It’s a research foundation,” she said. “It’s not industry.”
On her Food Politics blog, Nestle wrote on Wednesday about her objections to food manufacturers’ financial support of members of the editorial board of the American Journal of Clinical Nutrition, which publishes peer-reviewed nutrition studies. Of the 12 members of the editorial board, she wrote, seven list in their financial disclosures “major corporate affiliations” with food manufacturers including Coca-Cola, PepsiCo, McDonalds, and the Sugar Association.
What, if any, impact that has on the journal’s selection of studies to publish is unknown, but a 2007 study found that more than half of nutrition studies involving beverages were funded by drink makers and that none of the studies that was fully funded by beverage manufacturers reported negative results—compared with 37 percent of studies that did not rely on industry grants.