The study published in the Journal of Nutrition examined how whole and refined grain intake over time impacted five risk factors of heart disease. These included waist sizes, blood sugar, blood pressure, triglyceride, and HDL (“good”) cholesterol.
The study used data from the Framingham Heart Study Offspring Cohort, which began in the 1970s, to assess long-term risk factors of heart disease in 3,100 participants. Researchers examined health outcomes associated with grain consumption over a median of 18 years. Participants with diabetes at baseline were excluded.
Over four-year intervals, the research team compared changes in the five risk factors. Four categories of whole grain intake were created, ranging from less than half a serving per day to three or more servings per day. According to the Dietary Guidelines for Americans 2020-2025, the recommended amount of whole grains is three or more servings daily.
The study showed that waist size increased by an average of over 1 inch for every four-year interval in the low intake group, whereas it increased by only ½ inch in the high intake group of participants. After accounting for changes in waist size, increased systolic blood pressure and blood sugar levels were greater in low intake participants compared to high intake participants.
The researchers also looked at the five risk factors across the four categories of grain intake and found that lower intake led to a lower average increase in waist size and a more significant mean decline in triglyceride levels for each four-year period.
Nicola McKeown, senior and corresponding author said, “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.”
How Does it Work?
Researchers believe there may be several reasons why whole grains work to help people maintain waist size and reduce heart disease risk factors. The dietary fiber found in whole grains can have a satiating effect and the potassium, magnesium, and antioxidants may work to help lower blood pressure. Soluble fiber also may have an effect on post-meal blood sugar spikes.
It is essential to get to the recommended whole grain intake each day to get these health benefits. More research is needed to confirm the exact types of whole gains that are most beneficial as the impact of more processed whole grains was not studied as part of this research.