Greater whole-grain intake is associated with lower risk of type 2 diabetes, cardiovascular disease, and weight gain.
Whole-grain and high fiber intakes are routinely recommended for prevention of vascular diseases; however, there are no comprehensive and quantitative assessments of available data in humans. The aim of this study was to systematically examine longitudinal studies investigating whole-grain and fiber intake in relation to risk of type 2 diabetes (T2D), cardiovascular disease (CVD), weight gain, and metabolic risk factors. We identified 45 prospective cohort studies and 21 randomized-controlled trials (RCT) between 1966 and February 2012 by searching the Cumulative Index to Nursing and Allied Health Literature, Cochrane, Elsevier Medical Database, and PubMed. Study characteristics, whole-grain and dietary fiber intakes, and risk estimates were extracted using a standardized protocol. Using random effects models, we found that compared with never/rare consumers of whole grains, those consuming 48-80 g whole grain/d (3-5 serving/d) had an ~26% lower risk of T2D [RR = 0.74 (95% CI: 0.69, 0.80)], ~21% lower risk of CVD [RR = 0.79 (95% CI: 0.74, 0.85)], and consistently less weight gain during 8-13 y (1.27 vs 1.64 kg; P = 0.001). Among RCT, weighted mean differences in post-intervention circulating concentrations of fasting glucose and total and LDL-cholesterol comparing whole-grain intervention groups with controls indicated significantly lower concentrations after whole-grain interventions [differences in fasting glucose: -0.93 mmol/L (95% CI: -1.65, -0.21), total cholesterol: -0.83 mmol/L (-1.23, -0.42); and LDL-cholesterol: -0.82 mmol/L (-1.31, -0.33)]. [corrected] Findings from this meta-analysis provide evidence to support beneficial effects of whole-grain intake on vascular disease prevention. Potential mechanisms responsible for whole grains' effects on metabolic intermediates require further investigation in large intervention trials.
Program on Genomics and Nutrition, School of Public Health, University of California, Los Angeles, CA, USA.
Eva Qing
EQ
Ye
Sara A
SA
Chacko
Elizabeth L
EL
Chou
Matthew
M
Kugizaki
Simin
S
Liu
D001786:Blood Glucose / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000097:blood / Q000517:prevention & control*; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000517:prevention & control*; D004032:Diet; D004040:Dietary Carbohydrates / Q000494:pharmacology / Q000627:therapeutic use; D004043:Dietary Fiber / Q000494:pharmacology / Q000627:therapeutic use; D002523:Edible Grain; D002149:Energy Intake; D005511:Food Handling; D006801:Humans; D009765:Obesity / Q000097:blood / Q000517:prevention & control*; D012306:Risk; D015430:Weight Gain / Q000187:drug effects*
D001786:Blood Glucose; D008078:Cholesterol, LDL; D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D002784:Cholesterol