Common human biology
The current results from PURE “confirm prior observations from mostly Western nations that low intakes of fruits, vegetables, nuts, legumes, and fish are major risk factors for poor health,” observes Dariush Mozaffarian, MD, DrPH, MPH, Tufts University, Boston, in an accompanying editorial. “This suggests that common human biology, not merely confounding, explains these observed diet–disease relationships, strengthening causal inference on the power of nutrition.”
Moreover, “These findings provide further support that dairy foods, including whole-fat dairy, can be part of a healthy diet,” Dr. Mozaffarian writes. “The new results in PURE, in combination with prior reports, call for a re-evaluation of unrelenting guidelines to avoid whole-fat dairy products.”
Such studies “remind us of the continuing and devastating rise in diet-related chronic diseases globally, and of the power of protective foods to help address these burdens,” the editorial continues. “It is time for national nutrition guidelines, private sector innovations, government tax policy and agricultural incentives, food procurement policies, labeling and other regulatory priorities, and food-based health care interventions to catch up to the science.”
Not automatically superior
“I do not believe guidelines should be changed based on this single study,” contends Howard D. Sesso, ScD, MPH, associate director of the division of preventive medicine at Brigham and Women’s Hospital, Boston, who isn’t part of PURE. “But I welcome the scientific dialog that should come out of any study that challenges what we think we know,” he told this news organization.
“Many other dietary patterns have been identified over the years that also do a great job in predicting disease risk in observational studies,” observed Dr. Sesso. “Is PURE that much better? Maybe, maybe not. But not enough to dismiss other dietary patterns that are already the basis of dietary recommendations in the U.S., Europe, and worldwide.”
The PURE healthy diet score, he said, “appears to work well within the confines of their large pooling of studies around the world, but that doesn’t automatically make it superior to other dietary patterns.” The score “was only modestly, but not greatly, better than existing dietary patterns evaluated.”
Randomized controlled trials are needed, Dr. Sesso said, to “delve into more specific dietary components,” including unprocessed red meat, whole grains, and high-fat dairy foods. And, he said, more observational studies are needed to examine the score’s association with other cardiometabolic outcomes.
The PURE study is funded by the Population Health Research Institute, the Hamilton Health Sciences Research Institute, the Canadian Institutes of Health Research, the Heart and Stroke Foundation of Ontario; with support from Canadian Institutes of Health Research’s Strategy for Patient Oriented Research through the Ontario SPOR Support Unit, as well as the Ontario Ministry of Health and Long-Term Care; and through unrestricted grants from several pharmaceutical companies, with major contributions from AstraZeneca, Sanofi-Aventis, Boehringer Ingelheim, Servier, and GlaxoSmithKline. Additional contributions are from Novartis and King Pharma. Dr. Mente, Dr. Mozaffarian, and Dr. Sesso have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.