Study contradicts link between refined grains and CVD

Study contradicts link between refined grains and CVD

PHOENIX — Consumption of refined grains, widely viewed as contributing to chronic disease, is not associated with risk of cardiovascular disease (CVD), stroke or heart failure, according to a study published Sept. 19.

The research was published Sept. 19 in Trends in Cardiovascular Medicine. The study, conducted by Glenn A. Gaesser, PhD, a professor in the College of Health Solutions at the University of Arizona, followed a commentary published in July that showed no association between elevated refined grains intake and increased risk of type 2 diabetes.

Findings from both papers are at odds with the 2015 and 2020 Dietary Guideline Advisory Committees, which were based on dietary pattern research identifying “healthy” dietary patterns characterized by higher consumption of fruits, vegetables, whole grains, low-fat or non-fat dairy products, seafood, legumes and nuts, versus “unhealthy” (Western) dietary patterns characterized by higher intakes of red and processed meat, sugar-sweetened foods and beverages, french fries, high-fat dairy products, and refined grains.

Both the 2015 and 2020 DGACs concluded that a reduced intake of refined grains was associated with lower risk of CVD. Dietary advice from the American Heart Association aligned with the DGAC’s recommendations, characterizing refined grain products as “foods to displace” to achieve a heart-healthy dietary pattern.

To clarify the association between refined grain intake and CVD risk, the study conducted by Dr. Gaesser only included data from previous research examining refined grains as a distinct consumption category and not as part of a dietary pattern.

Because dietary pattern research does not provide for assessment of risks associated with each particular food group within a dietary pattern, Dr. Gaesser said it is plausible that the risk associated with refined grain intake is not attributable to refined grains per se, but to the other foods within the unhealthy dietary pattern.

For example, meta-analyses have shown that risk of CVD is associated with consumption of red and processed meat and sugar-sweetened beverages.

“Although refined grains are included as a component of the Western dietary pattern, the present findings suggest that refined grains do not contribute to the higher CVD risk associated with this unhealthy dietary pattern,” Dr. Gaesser said. “This information should be considered in formulation of future dietary recommendations.”

He said the findings are “consistent with results from a meta-analysis that showed that refined grain intake is not associated with risk of hypertension.”

Dr. Gaesser’s conclusion held for studies that analyzed only staple grain foods (bread, cereal, pasta and white rice) as well as for studies that included both staple and indulgent grain foods (flour-based desserts such as cakes, cookies, donuts, muffins and pastries) as a single refined grains category.

Six cohorts were from the United States, five cohorts were from Japan, three cohorts were from China, one cohort each was from Finland and Sweden. The analyses included data from the Prospective Urban and Rural Epidemiology (PURE) study, comprising data from 21 countries across 8 geographical regions. The results represented data from 1,218,232 participants.

Dr. Gaesser noted that in some of these studies, indulgent grain foods contributed significantly to total refined grain consumption. For example, in the Iowa Women’s Health Study “sweets and desserts” accounted for nearly one-half of refined grain intake.

Commenting on whole grains, Dr. Gaesser said most Americans could achieve significant reductions in the risk of CVD, CHD or stroke by increasing intake of whole grains by two servings per day (average intake currently is just under one serving).

“These findings suggest that it may not be necessary to replace refined grains with whole grains, but instead just encourage more whole grain consumption,” Dr. Gaesser said.

To prevent excessive energy intake, he said consumers increasing whole grains intake by two servings per day should pare back on consumption of refined grains by two servings per day.

While physical activity was controlled for in all but one study, none of the studies assessed sedentary behavior, which is a significant predictor of CVD risk independent of physical activity and may be a possible confounding variable to lessen the quality of evidence, the study said.

Dr. Gaesser is a scientific advisory board member of the Grain Foods Foundation and the Wheat Foods Council.