A whole grain diet reduces blood pressure in overweight/obese adults 151; a randomized control trial (249.3)

Abstract

Epidemiological studies suggest that dietary whole grain intake is associated with a lower incidence of cardiovascular disease. However, there are no Level‐1 data from randomized control trials (RCT) to support these observations. We performed a double‐blind crossover RCT in 40 sedentary overweight/obese (39.1±1.1 years, BMI: 32.5±0.7 kg/m2) adults to test the hypothesis that a whole grain diet reduces cardiovascular risk. Diets were provided based on meeting nutritional guidelines for fat, protein and carbohydrate (i.e. ~28, 18, and 54%) and contained either whole grain (50 g/1000 kcal), or refined grain. Each diet was provided for 8 weeks with an 8‐10 week washout period between diets. A total of 33 subjects completed the study. Mean energy intake, based on resting metabolic rate and a sedentary lifestyle activity factor, was similar between the whole grain and refined grain diets (2051.4±60.7 and 2032.8±60.1 kcal/d, P=0.46). Diets were also similar in macronutrient intake, saturated fat, dietary cholesterol, sodium, and potassium. Compared to baseline, the whole grain and refined grain diets induced similar weight/fat loss (~2 kg, P<0.05). Both diets reduced cholesterol, LDL cholesterol and triglycerides (all P<0.05), but insulin was only reduced after the whole grain diet (P<0.05). Although both diets reduced systolic blood pressure by ~3.5 mmHg, the improvement in diastolic blood pressure (‐5.9±1.1 vs. ‐2.3±1.4 mmHg, P<0.05) and pulse pressure (2.6±2.1 vs. ‐2.5±1.6 mmHg, P<0.05) was significantly greater after the whole grain compared to the refined grain diet. We conclude that a whole grain diet reduces cardiovascular risk factors and produces a clinically significant reduction in diastolic blood pressure in overweight/obese adults independent of weight loss. Since diastolic blood pressure is a predictor of mortality in adults under the age of 50 years, increased whole grain intake may provide a protective nutritional prevention and treatment strategy for hypertension.Grant Funding Source: A grant‐in‐aid from Nestle and NIH UL1‐RR024989