Eating more whole grains may help patients maintain waist size, BP, blood sugar
Patients who ate at least three servings of whole grains per day had smaller increases in waist circumference, BP and fasting glucose concentration than patients who ate less than half a serving per day, data show.
The association appeared to be stronger in women, Caleigh M. Sawicki, PhD, MPH, an epidemiologist with the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, and colleagues reported in The Journal of Nutrition.
According to the researchers, compared with refined grains, whole grains are higher in fiber, vitamin E, magnesium, potassium and other components that have cardiometabolic health benefits. However, adults in the United States typically eat fewer whole grains — less than one serving per day — and more refined grains — about five to six servings per day.
“Some, but not all, studies indicate higher intake of [refined grains] is associated with greater risk of CVD,” Sawicki and colleagues wrote. “Therefore, higher [whole grain] intake, substituted for [refined grain], is a potential dietary strategy to lower CVD risk.”
The researchers analyzed data on 3,121 middle- to older-aged participants in the Framingham Offspring cohort study. The mean age at baseline was 54.9 years. About half of the participants were women (54.5%), and most (64.4%) were overweight or obese.
Sawicki and colleagues assessed participants’ food frequency questionnaires and health and lifestyle data every 4 years over a median follow-up period of 18 years. They used repeated measure mixed models to estimate the adjusted mean changes in CVD risk factors across increasing categories of whole grain or refined grain consumption.
On average, the participants reported consuming one serving of whole grains and three servings of refined grains, according to the researchers. Only 3.8% of participants consumed at least three servings of whole grains per day. Most whole grain consumption was from dark or whole wheat bread (47%) and ready-to-eat breakfast cereal (36%). Meanwhile, most refined grain consumption was from white bread (22%) and pasta (20%).
Compared with participants who consumed half a serving of whole grains per day, the researchers reported that those who consumed at least three servings of whole grains per day experienced smaller increases in waist circumference (1.4 ± 0.2 vs. 3.0 ± 0.1 cm; P < .001), fasting glucose concentration (0.7 ± 0.4 vs. 2.6 ± 0.2 mg/dL; P < .001) and systolic BP (0.2 ± 0.5 vs. 1.4 ± 0.3 mm Hg; P < .001) for each 4-year interval.
“When stratified, both females and males had a significant trend toward a smaller mean increase in [waist circumference] across increasing [whole grain] intake categories, and the effect was larger among females,” the researchers wrote.
Conversely, compared with participants who consumed less than two servings of refined grains per day, those who consumed at least four servings of refined grains per day had greater mean increases in waist circumference (2.7 ± 0.2 vs. 1.8 ± 0.1 cm; P < .001) and a smaller mean decline in fasting plasma triglyceride concentration (0.3 ± 1.3 vs. 7.0 ± 0.7 mg/dL; P < .001) per 4-year interval.
All these findings remained significant after adjusting for BMI, change in waist circumference and other dietary factors, according to the researchers.
Despite the limitations of the study, including the use of self-reported data and the predominately white cohort, Sawicki and colleagues said the findings support recommendations to replace refined grains with whole grains, “particularly as a dietary modification to attenuate abdominal adiposity, hypertension and hyperglycemia, and thereby reduce the risk for cardiometabolic disease.”
“There are several reasons that whole grains may work to help people maintain waist size and reduce increases in the other risk factors,” Sawicki said in a press release. “The presence of dietary fiber in whole grains can have a satiating effect, and the magnesium, potassium and antioxidants may contribute to lowering BP. Soluble fiber in particular may have a beneficial effect on post-meal blood sugar spikes.”