A recently released study published in The Journal of Nutrition provides further support that greater whole grain and lower refined grain intake is associated with healthier cardiometabolic health risk factors.
Observational studies have found that greater whole grain consumption is associated with a lower risk of cardiovascular disease, obesity, type 2 diabetes, and hypertension. Although many factors increase a person’s risk of these chronic, degenerative diseases, diet is especially important because it is a modifiable risk factor. One particularly important strategy to lower cardiovascular risk is replacing refined grains with whole grains. Yet, few long-term, prospective observational studies have examined the relations between whole grain or refined grain intake and changes in blood lipids or blood glucose concentrations.
To better understand the relationship between habitual whole grain consumption and changes in cardiometabolic risk factors, Nicola McKeown (Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University) and colleagues conducted a prospective study using data collected from the National Heart, Lung, and Blood Institute Framingham Heart Study Offspring Cohort. The Framingham Heart Study is a multi-generational long-term, community-based population study that was initiated in 1948 to study determinants of cardiovascular disease. In 1971, offspring of the original cohort were recruited into the Offspring Cohort.
Approximately every 4 years, participants undergo standardized medical histories and physical examinations. Data from the 5th, 6th, 7th, 8th, and 9th study examinations were included in these analyses. The Harvard semiquantitative food frequency questionnaire was used to assess dietary intake, and a whole grain database enabled researchers to quantify grams per day of whole grain consumption. Refined grain consumption was based on servings per day of the following food items: refined cold ready-to-eat breakfast cereal, cooked breakfast cereal (not oatmeal), white bread, English muffins, bagels, muffins, biscuits, white rice, pasta, pancakes, waffles, crackers, and pizza. Cardiometabolic risk factors included waist circumference, systolic blood pressure, diastolic blood pressure, blood lipids, and blood glucose.
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Greater whole grain intake was associated with smaller increases in waist circumference, fasting glucose concentration, and systolic blood pressure per 4-year interval. When stratified by sex, a stronger association with waist circumference was observed among females than males. Although the observed association between whole grain consumption and waist circumference was relatively small, even small gains in abdominal adiposity can impact disease risk. Higher intake of whole grain was also associated with greater increases in HDL cholesterol and declines in triglyceride concentrations, although results showed a complex relationship with waist circumference. In contrast, higher refined grain intake was prospectively associated with higher gains in abdominal adiposity and triglyceride concentrations.
The prospective changes in cardiometabolic risk factors observed in this study support current dietary recommendations to replace refined grain foods with whole grain equivalents. Dietary modification to attenuate abdominal adiposity, hypertension, and hyperglycemia are impactful and can help reduce risk and lessen the severity of cardiovascular disease.
Sawicki CM, Jacques PF, Lichtenstein AH, Rogers GT, Ma J, Saltzman E, McKeown NM. Whole- and Refined-Grain Consumption and Longitudinal Changes in Cardiometabolic Risk Factors in the Framingham Offspring Cohort. J Nutr., Volume 151, Issue 9, September 2021, Pages 2790–2799, https://doi.org/10.1093/jn/nxab177.
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