Whole Grain Intake Linked to More Preferable Cardiometabolic Profile in Aging Adults, USDA-Funded Study Finds

Nicola McKeown, PhD

A new study suggests middle- to older-aged adults consuming at least 3 servings of whole grains daily was linked to lesser declines in glycemic control and blood pressure.

Performed by investigators at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, the analysis of data from the Framingham Heart Study Offspring indicates those who consumed greater amounts of whole grain experienced smaller increases in waist circumference, blood pressure, and blood sugar levels over time.

"Our findings suggest that eating whole-grain foods as part of a healthy diet delivers health benefits beyond just helping us lose or maintain weight as we age. In fact, these data suggest that people who eat more whole grains are better able to maintain their blood sugar and blood pressure over time. Managing these risk factors as we age may help to protect against heart disease," said Nicola McKeown, PhD, study lead investigator and a scientist on the Nutritional Epidemiology Team at the USDA HNRCA, in a statement.

With an interest in describing how whole and refined-grain consumption might influence cardiometabolic risk profiles, McKeown and a team of colleagues sought to explore potential associations between increased intake of whole grains and refined grain on waist circumference, fasting HDL-C, triglycerides, glucose concentrations, and blood pressure. To do so, investigators designed their study to assess these associations using data from the Framingham Heart Study Offspring Cohort, which included more than 5000 offspring from the original cohort.

Using only patients who completed multiple dietary exams and who were without known diabetes at baseline, investigators identified a cohort of 3121 participants for inclusion in their final analyses. As part of the original study, diet was assessed according to the Harvard semiquantitative food frequency questionnaire (FFQ).

In total, 9231 observations were included in the analyses. The mean number of exams attended was 4 and the median total follow-up time of the study cohort was 18.1 (IQR, 7.0) years. At baseline, the mean age of participants was 54.9±0.17 years, 54.5% were female, and 64.4% reported having overweight or obesity.

After adjustment for confounding factors, results indicated greater intake of whole grains was associated with smaller increases in waist circumference (1.4±0.2 vs 3.0±1.0 cm; P-trend <.001), fasting glucose concentration (0.7 ± 0.4 vs 2.6±0.2 mg/dL; P-trend < .001), and systolic blood pressure (0.2±0.5 vs 1.4±0.3 mmHg; P-trend < .001). Stratification by patient sex suggested a stronger association with waist circumference was present among females than males.

Additionally, results indicated increased intake of whole grains was associated with greater increased in HDL-C and declines in triglyceride concentrations. Investigators did point out this difference failed to maintain significance after adjustment for change in waist circumference. However, results also suggested increased intake of refined grains was associated with greater increases in waist circumference (2.7±0.2 vs 1.8±0.1 cm; P-trend < .001) and lesser reductions in triglyceride concentration (-0.3±1.3 vs -7.0±0.7 mg/dL; P-trend < .001).

"There are several reasons that whole grains may work to help people maintain waist size and reduce increases in the other risk factors. The presence of dietary fiber in whole grains can have a satiating effect, and the magnesium, potassium, and antioxidants may contribute to lowering blood pressure. Soluble fiber in particular may have a beneficial effect on post-meal blood sugar spikes," said Caleigh Sawicki, PhD, MPH, member of the Nutritional Epidemiology Team at the USDA HNRCA.

This study, “Whole- and Refined-Grain Consumption and Longitudinal Changes in Cardiometabolic Risk Factors in the Framingham Offspring Cohort,” was published in the Journal of Nutrition.