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.