November 20th, 2013

Consumption of Nuts Linked to Mortality Benefit

Nut consumption has long been linked to healthy lifestyles. Now, a study in the New England Journal of Medicine extends the finding and demonstrates a strong association with improved mortality.

Ying Bao and colleagues examined data from nearly 120,000 people enrolled in the Nurses’ Health Study and the Health Professionals Follow-up Study to assess the relationship of nut consumption and mortality. With over 3 million person-years of follow-up, the investigators found a strong inverse correlation between the frequency of nut consumption and mortality, after adjusting for other risk factors.

Here are the hazards ratio for death based on frequency of nut consumption (compared to no consumption):

  • Less than once per week: 0.93 (CI 0.90-0.96)
  • Once per week: 0.89 (CI 0.86-0.93)
  • 2-4 times per week: 0.87 (CI 0.83-0.90)
  • 5-6 times per week: 0.85 (CI 0.79-0.91)
  • 7 or more times per week: 0.80 (CI 0.73-0.86)

Similar results were observed in both men and women separately. As well, there were significant reductions in deaths due to cancer and heart disease. The results were also similar when the investigators looked separately at the role of peanuts (a legume) and tree nuts.

Although nuts are often thought to cause weight gain, the investigators reported that increased nut consumption was associated with less weight gain in their study.

The authors acknowledged that as it was an observational study, they were not able to demonstrate a cause and effect relationship between nut consumption and mortality. However, they wrote, “our data are consistent with a wealth of existing observational and clinical-trial data in supporting the health benefits of nut consumption for many chronic diseases.” The ingredients in nuts “may confer cardioprotective, anti-carcinogenic, anti-inflammatory, and antioxidant properties.”

Recommended viewing: A NEJM animation, with narration by editor Jeffrey Drazen, explaining the study and its implications.

4 Responses to “Consumption of Nuts Linked to Mortality Benefit”

  1. What should we do with these diet studies? They come out to great fanfare. The media love them. Diane Sawyer said on the evening news that nuts have health effects, far outrunning what you can say from the data. We all know the great limitations of these studies. I wonder what people are telling patients who ask… should I eat nuts to increase my chance of living longer? And should we, based on this study, be advocating that people eat nuts to reduce weight gain????

  2. I am unimpressed with the effect size (it is below the threshold for reliable and replicable estimates derived from observational data) but intrigued by the exposure-response and consistency of effects in both genders.

  3. Edgar Abovich, MD says:

    This whole thing is nuts! I think it is more of a business decision to publish this article, since it helps the bottom lines of NEJM, as well as networks, etc. Sure, what people eat is very important, and some variation of the Mediterranean diet is probably good for you, but adding nuts to hamburgers and fries is not going to help.

  4. Should we care that the study was funded by the International Tree Nut Council Nutrition Research and Education Foundation? Or is this information not really germane? For studies that are sponsored by a group with a commercial interest and with a result that favors their products, should we insist that the data be made public so that others can analyze it?