Eating half a handful of nuts every day could substantially lower the risk of early death, a Dutch study suggests.

Several preceding studies have found eating a modest amount of nuts every day might significantly reduce our risk of dying from cardiovascular (heart) disease, but this study found it reduces the risk of dying from a number of chronic diseases.  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.

More than 120,000 Dutch 55-to-69-year-old men and women provided dietary and lifestyle information in 1986, and then their mortality rate was evaluated at 10 years later.

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.

Maastricht University researchers found a 23% lower chance of death during the 10-year study in people eating at least 10g (0.3oz) of nuts or peanuts a day, compared to people who didn’t eat nuts.

Prof Piet van den Brandt, who led the study, published in the International Journal of Epidemiology, said: “It was remarkable that substantially lower mortality was already observed at consumption levels of 15g of nuts or peanuts on average per day.”

The researchers took into account the mitigating factor that nut consumers ate more fruit and vegetables and that women who ate nuts were often leaner, and adjusted the results accordingly.

The premature mortality risk due to cancer, diabetes, respiratory (lung) and neurodegenerative diseases was lower among the nut consumers. There was an average 23% lower risk of 10-year mortality across all diseases, with a decrease of:

  • 45% for neurodegenerative disease
  • 39% for respiratory disease
  • 30% for diabetes

There was no benefit for peanut butter, which is high in salt and trans fats.

“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.)

The scientists offered a word of caution, indicating there is an upper beneficial consumption amount, in the study, above which there was no further benefit from eating nuts. And while peanut butter didn’t offer any benefits (possibly due to the addition of other oils and ingredients during the manufacturing process, peanuts did.

About half a handful of nuts is the effective amount – 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.