Whole-grain intake as a marker of healthy body weight and adiposity.

OBJECTIVE To review evidence relating to the consumption of whole grains and healthy body weight (BW). DESIGN Systematic review and analysis of observational studies reporting whole-grain consumption and measures of BW and adiposity, including the effect on macronutrient intakes and lifestyle factors. SETTING Medline and other databases were searched for the period 1990 to 2006 to produce a full reference list; observational studies were retained for further analysis if they included an appropriate control group and reported whole-grain intake and body mass index (BMI) or a measure of adiposity. SUBJECTS Fifteen trials were identified which included data from 119 829 male and female subjects aged 13 years and over. RESULTS The combined and weighted mean difference in BMI from 15 studies representing 20 treatment groups (n = 119 829) using a random-effects model was 0.630 kg/m2 lower when high versus low whole-grain intake was compared, P < 0.0001 (95 % confidence interval (CI) 0.460, 0.800 kg/m2). In high consumers, adiposity assessed as waist circumference was reduced by 2.7 (95 % CI 0.2, 5.2) cm, P = 0.03 (six data sets, n = 4178) or as waist:hip ratio by 0.023 (95 % CI 0.016, 0.030), P < 0.0001 (four data sets, n = 20 147). Higher intake of whole grains led to increased dietary fibre intake (9 g, P < 0.01), while total and saturated fat intakes decreased by 11 g and 3.9 g, respectively. CONCLUSION A higher intake of whole grains (about three servings per day) was associated with lower BMI and central adiposity. In addition, people who consume more whole grains are likely to have a healthier lifestyle as fewer of them smoke, they exercise more frequently and they tend to have lower fat and higher fibre intakes.