Consuming more whole grains may protect against heart disease, a new study suggests.
An analysis of over 3,000 middle- and older-age adults over many years found that those who ate at least three servings of whole grains daily had smaller increases in blood sugar levels, blood pressure, and waist size, compared to those who ate less than one-half serving per day.
“We found that there were no long-term studies of how people are actually living, without intervention, that examined the relationship between intake of whole or refined grains and changes in certain risk factors that are early warning signs of disease, including waist size, blood pressure, and blood sugar,” author Caleigh Sawicki, PhD, a nutritional epidemiologist formerly of Tufts University in Boston, tells WebMD. “This is an important step in understanding how different types of grains may influence health over time.”
The researchers used data from 3,121 people who took part in the Framingham Heart Study Offspring Cohort, a study that launched in the 1970s to examine long-term risk factors for heart disease. The average age of the participants was about 55 at baseline.
Changes in the following five risk factors for heart disease at 4-year intervals over the course of approximately 18 years were analyzed: waist size, blood pressure, blood sugar, triglycerides (a type of fat found in the blood), and HDL cholesterol, or “good” cholesterol.
Participants were grouped into categories based on the amount of whole grains they reported eating, ranging from low whole-grain intake (less than one-half serving every day) to three or more servings per day.
For each 4-year interval, the researchers found that waist size increased by about one-half inch in people who had high whole-grain intake, compared to 1 inch in those who had low intake. Average increases in blood pressure and blood sugar levels were also lower in high-intake adults.
In a similar analysis of refined grain intake, adults who reported eating fewer refined grains had a lower increase in waist size and lower triglyceride levels over time.
“This suggests that including whole grains, especially in place of refined grains, as part of a healthy diet could help us maintain healthier levels of these risk factors as we age, and, therefore, may help to prevent the development of heart disease,” Sawicki says, adding that dietary fiber in whole grains may help promote a feeling of fullness and lower blood sugar spikes after meals.
The Dietary Guidelines for Americans 2020-2025 recommend eating at least three servings of whole grains every day. One serving of whole grains, for example, includes a half-cup of brown rice or rolled oats.
Next, the researchers plan to examine if consuming whole grains, compared to refined grains, leads to changes in the type of belly fat a person gets, says Nicola McKeown, PhD, a scientist with the Nutritional Epidemiology Team at the U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University.
“Other research has shown that it may be excess visceral fat which surrounds our organs, rather than overall body fat, that is more dangerous in terms of disease risk. We want to know whether whole or refined grain intake may be associated with changes in one type of fat more than the other,” says McKeown.
