November 21, 2013
People who eat nuts at least once a week have a lower risk of death, compared with people who never eat them, says a large study. Researchers used information from more than 110,000 people. They were part of two large, long-term studies of health professionals. Over the course of the studies, about 27,000 people died from all causes. People who ate nuts every day were 20% less likely to have died during the study, compared with people who never ate nuts. Those who ate nuts once a week were about 7% less likely to die. The study also found that eating nuts was linked with lower risks of death from cancer, heart disease and lung disease. The study was published in the November 21 issue of the New England Journal of Medicine. Reuters Health and other media outlets wrote about it the same day.
By Robert S. Shmerling, M.D.
Harvard Medical School
What Is The Doctor's Reaction?
I have to admit I was skeptical about new research suggesting that eating nuts could lengthen your life.
But, it may be true. Previous studies have noted a link between nut consumption and a lower incidence of type 2 diabetes, heart attacks and other chronic diseases. This led researchers to analyze the relationship between eating nuts and causes of death among nearly 119,000 men and women.
The findings were remarkable. Death rates were significantly lower among those who ate nuts compared to those who did not. And the more nuts consumed, the lower the rates of death:
- Those eating nuts once a week had a death rate that was 11% lower than those who didn’t eat nuts.
- Those eating nuts 2 to 4 times each week had a 13% lower death rate
- Those eating nuts 5 or 6 times each week had a death rate that was 15% lower
- A 20% lower rate of death was observed for those eating nuts 7 or more times each week
Lower rates of death among people eating nuts may have been due to another of the study’s conclusions: higher nut consumption was linked with lower rates of heart disease, lung problems, and cancer.
While these findings are impressive, it’s worth remembering that finding lower rates of disease and death among people eating nuts does not prove that nut consumption was the actual cause. There’s always a possibility of faulty recall in a studies like this one that rely on dietary self-report. Or, maybe it’s not the nuts that matter – perhaps people who eat nuts have healthier habits (such as less smoking or more exercise) than those who don’t like nuts. While the study tried to account for these other factors, it’s always possible that something other than nut consumption was responsible for the findings.
Still, the size of this study, its execution over several decades, and the “dose-response” (the more nuts consumed, the more benefit) make the conclusions hard to ignore.
What Changes Can I Make Now?
This study suggests that if nuts are not already part of your diet, it may be time for a change.
Before making this change, however, you may wonder:
- Which nuts are best? Researchers in this latest study asked about two types of nuts: peanuts and tree nuts (which include almonds, cashews, pecans, walnuts and many others). Similar benefits were noted for both types. So, the type of nuts you eat may not matter. Then again, researchers didn’t collect detailed information about the various types of tree nuts.
- How should nuts be prepared? That’s hard to say. This study did not ask whether the consumed nuts were raw, roasted or seasoned. There was also limited information about serving size.
- Wouldn’t eating a lot of nuts lead to weight gain? Good question! Nuts are high in fat and they pack a lot of calories. But, previous research has been reassuring on this point. People who eat nuts regularly tend to have a lower risk for obesity, compared with people who never eat nuts.
- Who funded this study? That’s a question that’s almost always worth asking. Bias – whether intentional or not – is a common concern and can be minimized by limiting the role of the study sponsor in designing, performing or documenting the trial. Sponsors of this study included the National Institutes of Health and the International Tree Nut Council Nutrition Research and Education Foundation. However, according to the authors, the funding institutions’ roles were appropriately limited.
Despite the findings, increasing nut consumption isn’t for everyone. Some people are allergic to nuts. Others just don’t like them. We don’t know enough about the role of nut consumption in health and disease to suggest eating nuts to everyone who is willing to do so. But it’s worth considering.
What Can I Expect Looking To The Future?
In the future, it’s likely that additional research will explore how nut consumption affects health and why it may be associated with longer life. There are a number of possibilities. For example, nuts are high in:
- Unsaturated fatty acids
- Vitamins (including folate, niacin, and vitamin E)
- Plant-based substances, such as carotenoids and flavonoids, which may be good for the heart and have anti-cancer, anti-oxidant and anti-inflammatory effects
I think we’ll continue to learn more about which foods are healthiest. It’s likely that no single food will turn out to be vitally important and that a balance of different foods (including nuts) will be best. But, identifying which foods are healthiest is probably the easy part. The harder part is figuring out how to get people to choose those foods over others.