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In a nutshell: small brief study measuring the impact of pecan supplementation can’t tell us much

Eating pecans had significant effect on biomarkers of heart disease and type 2 diabetes

Our Review Summary

This release summarizes a small 4-week study of 26 middle-aged adults with overweight or obesity. Researchers from Tufts University examined the effects of eating 1.5 ounces of pecans daily on the volunteers’ cardiovascular biomarkers. The release notes pecans produced “significantly improved insulin sensitivity and had a significant effect on markers of cardiometabolic disease in otherwise healthy overweight and obese adults with excess belly fat.”

The release gives readers little in the way of evidence or help in understanding the actual benefits (as opposed to changes in biomarkers) someone supplementing with pecans could experience.


Why This Matters

People are hungry for good advice on how to eat in order to lessen their risk of chronic diseases, including cardiovascular diseases. But this short news release paints a too simple picture based on a month-long study of a few patients.

This study measured biomarkers in blood that are associated with health outcomes in order to find out whether eating pecans changed their health outcomes, but it did not follow these patients beyond four weeks. Sometimes a biomarker is just a surrogate that does not help patients understand real health outcomes. We wish the National Pecan Sheller’s Association, which funded the study, had taken a longer look at more meaningful outcomes.

Read more about the misleading nature of some nutrition studies.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The release does not mention the cost of pecans. More expensive than some other tree nuts, the ballpark price of pecans should be known to the average reader.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The release does not give us numerical measures of the benefits it reports from the study. Instead, the release uses the phrase “significantly improves” in relation to “insulin sensitivity” and further states that pecans had a “significant effect on markers of cardiometabolic disease in otherwise healthy overweight and obese adults with excess belly fat.”

None of that helps readers gauge the impact of pecan supplementation.

The lead researcher is quoted saying, “What’s really interesting is that just one small change — eating a handful of pecans daily — may have a large impact on the health of these at-risk adults.” But no where in the releases are readers provided any evidence of a large impact.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

There is no mention of any possible harms from adding pecans to the diet. A brief mention of nut allergies and the high fat and calorie content of nuts would be appropriate in a release advocating daily pecan supplementation.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The release provides a very brief summary of the study design that provides a backdrop for the reader.  However, the beneficial effects as stated are not as clear as they could be. While insulin sensitivity was reportedly improved with the pecan added to the diet, the fact that a composite endpoint of cardiovascular markers was used in the study was not disclosed in the release. The study authors noted in the published report, “Pecan consumption lowered the risk of cardiometabolic disease as indicated by a composite score reflecting a significant change in clinically relevant markers, i.e., blood lipids and glucoregulation. Using a composite score to concurrently analyze changes in several markers is not unique. However, our method, which used reference ranges to normalize the markers, demonstrates how appropriately aggregating similar markers increases statistical power to detect a difference between groups.”

The release could give the reader the incorrect impression that biomarkers were individually improved.

Does the news release commit disease-mongering?


There is no disease mongering.

Does the news release identify funding sources & disclose conflicts of interest?


The news release made it clear that the study was funded by the National Pecan Shellers Association. The published study also noted that the researchers had no conflicts of interest.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

There are many different dietary recommendations that could lower a person’s risk of heart disease and type 2 diabetes. This release does not discuss any other strategies for lowering the risk of type 2 diabetes or heart disease.

Does the news release establish the true novelty of the approach?


The release states that this study is “the first study to look at the effects of pecan consumption on factors other than blood lipid levels and specifically those related to T2D. Obesity is a risk factor for T2D, and both obesity and T2D increase CVD risk.”

We don’t know whether pecans are similar enough to other well-studied nuts that perhaps there is already quite a bit of evidence.

Total Score: 4 of 9 Satisfactory


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