June 17, 2014
Dwight W. Lewis, Jr., PhD, postdoctoral fellow in the Nutrition Obesity Research Center (NORC) and Office of Energetics—collaborating with Edward Archer, PhD, postdoctoral fellow in the Office of Energetics, and David B. Allison, PhD, distinguished professor and director of NORC and the Office of Energetics—summarized reviews of trials and studies investigating the relationship between health and nut intake.
Since the late 1990s, there have been a large number of short-term trials and observational studies investigating the relationship between nut consumption and health. Many of the findings from these short-term trials and observational studies suggest that increased nut consumption reduces diabetes, coronary artery disease, mortality, and stroke risk. Dr. Lewis and his colleagues recently reported that key findings from the systematic reviews and meta-analyses suggest that increased nut consumption is modestly correlated with lower coronary artery disease risk and that there is no association between nut intake and stroke and mortality; the suggested relationship between nut consumption and diabetes is inconsistent.
The researchers went in-depth about key limitations from the current literature that were not highlighted by the authors of the systematic reviews and meta-analyses and pointed out that any suggested causal relationships between nut intake and health in the current literature is constrained by the low presence of randomized control trials and an overreliance of self-reported food intake as a proxy for actual intake. They further explained that the low application of randomizing nut intake in current studies’ research design makes it difficult to determine whether associations exist because nut intake makes people healthy or that healthy people tend to eat nuts. Also discussed is the frequent use of self-report food intake, especially via food frequency questionnaires, which serves as a potential threat to the validity of study findings because some survey participants are not likely to be honest about their diet behavior.
Dr. Lewis and the team concluded that although there is insufficient evidence for a causal relationship between nut intake and health, it at least appears to be plausible that nuts have some health benefit. Therefore, if a person is not allergic to nuts and enjoys its consumption, then eating them in moderation seems to be a wise decision.
To read “The Plausible Health Benefits of Nuts: Associations, Causal Conclusions, and Informed Decisions,” published online in the May 2014 issue of the American Journal of Clinical Nutrition, click here.