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

Abstract

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/m 2 lower when high versus low whole-grain intake was compared,P< 0·0001 (95 % confidence interval (CI) 0·460, 0·800 kg/m 2). 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.