Whole grain and weight management: an intervention study to clarify underlying mechanisms

INTRODUCTION: Epidemiological studies associate whole grain (WG) consumption to reduced CVD risk, body weight and abdominal circumference. Data obtained by intervention studies were not conclusive. Evidence from animal and few human studies indicated that prebiotic dietary fibre ameliorates metabolic syndrome and controls body weight through reduction of inflammation. OBJECTIVES: This study aims i) to evaluate the effect of WG on body weight, circumferences and composition, ii) to clarify the underlying mechanisms. DESIGN: A commercial WG product, having prebiotic properties and a high amount of polyphenols bound to dietary fibre, was selected. Eighty healthy overweight subjects will be enrolled. Forty volunteers will be asked to slightly change their habitual diet replacing equicaloric portions of specific foods with 68 g WG/die for 8 weeks; the other half will not change their diets. At baseline, and after 4 and 8 weeks, measure of body weight, waist and hip circumferences, bioimpedance analysis and blood, urine and feces collection will be performed. Markers linked to antioxidant status (serum ferulic acid, β-carotene and FRAP), to inflammatory status (several cytokines by multiplexed immunometric assay), to lipid and glucose metabolism as well as to the overall nutritional status and appetite, will be measured. RESULTS: Preliminary data indicated that in subjects consuming WG, starting from 4 wk of treatment: i) both body weight and waist circumference were significantly reduced by 5% and 4% from baseline, respectively; ii) ferulic acid concentration was significantly doubled both in serum and urine, and triplicated in feces; iii) both fullness and satiety were doubled, while hunger did not vary from baseline. CONCLUSIONS: The study is still ongoing but data obtained up to now indicated a good bioavailability of ferulic acid by WG consumption and encouraging perspectives as regards body weight management. The completion of protocol and analyses will permit to clarify the underlying mechanisms.