A comparison of the literature on the association between intakes of bran, cereal fiber, and whole grains and risk of adiposity measures

Definitions of whole grains vary depending on context and purpose, creating a gap between the findings of nutrition science and the dietary guidance consumers receive. A review of the scientific literature was conducted to evaluate the impact of these grain components on adiposity measures. MEDLINE was used to search the scientific literature for relevant studies. Additional studies were identified by bibliographic searches for relevant articles. Editorials, reviews, and studies published in languages other than English were excluded. Intakes of cereal fiber, bran, mixtures of whole grain and bran, and whole grains were generally inversely associated with adiposity measures; cereal fiber intake had the most consistent associations. The association between whole grains and weight gain reduction was attenuated after adjustments for fiber and micronutrients. Most whole grain analyses included ~25% bran in the whole grains food category. Thus, most studies reported as providing evidence on whole grains were substantially confounded by including bran containing foods. The small number of studies that reported effects from whole grain foods alone showed inconsistent effects on body weight measures. The data suggest that bran and cereal fiber are active components of whole grains. Funded by a grant from the Kellogg company.