Like several before it, a new study finds that eating a modest amount of nuts every day might significantly reduce our risk of dying from a number of chronic diseases. And these include not only a reduced risk of mortality from heart disease, which has been the most-studied benefit of nuts, but also cancer, stroke, respiratory disease, and brain diseases. This is excellent news for nut lovers, but the researchers give a word of caution: Don’t completely go nuts, so to speak. There was an upper limit in the study, above which there was no further benefit from eating nuts. And while peanut butter didn’t offer any benefit (sadly), peanuts did, which suggests that although they’re not technically nuts (they’re legumes), they do have a right to continue masquerading as nuts.
[Update: People have been writing in, pointing out that if you have serious nut allergies, the results may not apply (this is mostly true), or taking issue with the "death from any cause" phrase, since nuts won't actually save you from things like falling off a cliff. This is also true. It just implied "death from the multiple major causes that were included in the analysis." In the future I'll spell that out more, and have changed to title to reflect that.]
The researchers looked at data from over 120,000 Dutch people who have been taking part in the Netherlands Cohort Study since 1986. They tracked the participants’ dietary habits, and health outcomes over a period of 10 years. Included in the analysis were tree nuts, peanuts, and peanut butter. Though peanuts are legumes, they share many nutritional properties of nuts, including monounsaturated and polyunsaturated fatty acids, vitamins, antioxidants, and fiber, so are often included in studies like this one.
It turned out that people who regularly ate nuts had a reduced risk of death from all of the causes included in the analysis – about 23% reduce risk, compared to people who didn’t eat nuts. And while most studies in the past have been interested in the links between nuts and cardiovascular disease, the current study found the benefit also applied to death from other diseases including cancer, stroke, diabetes, respiratory, and neurodegenerative diseases. The reduction in risk of developing neurodegenerative disease like Alzheimer’s was robust: for someone who ate 10 or more grams of nuts per day, it was about 45% less than someone who ate none.
“It was remarkable that substantially lower mortality was already observed at consumption levels of 15 grams of nuts or peanuts on average per day (half a handful),” said study author Professor Piet van den Brandt. “A higher intake was not associated with further reduction in mortality risk. This was also supported by a meta-analysis of previously published studies together with the Netherlands Cohort Study, in which cancer and respiratory mortality showed this same dose-response pattern."
Unfortunately, peanut butter didn’t have the same protective effects as nuts proper, possibly because it sometimes includes added oils (including trans fats), salts, and sugars.
But the good news is that peanuts did. It's also not the first study to suggest impressive health benefits linked not only to nuts, but to peanuts. In March, a JAMA Internal Medicine study found that people who ate nuts, including just peanuts, had a significantly lower risk of death from heart disease and overall mortality. And this, together with the current study, suggests that it’s not necessarily the most expensive varieties of nuts that confer the benefits. (But like the current study, peanut butter didn’t seem to offer a benefit.)
As van den Brandt mentioned, about half a handful of nuts was the effective “dose” – more than that didn’t seem to reduce mortality any further. That’s bad news for some of us who may have a hard time stopping at half a handful. But for people with normal levels of self-restraint, the study results should come as very good news.
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