Greater whole-grain intake is associated with lower risk of type 2 diabetes, cardiovascular disease, and weight gain

J Nutr. 2012 Jul;142(7):1304-13. doi: 10.3945/jn.111.155325. Epub 2012 May 30.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Blood Glucose / metabolism
  • Cardiovascular Diseases / blood
  • Cardiovascular Diseases / prevention & control*
  • Cholesterol / blood
  • Cholesterol, LDL / blood
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / prevention & control*
  • Diet*
  • Dietary Carbohydrates / pharmacology
  • Dietary Carbohydrates / therapeutic use
  • Dietary Fiber / pharmacology
  • Dietary Fiber / therapeutic use
  • Edible Grain*
  • Energy Intake*
  • Food Handling
  • Humans
  • Obesity / blood
  • Obesity / prevention & control*
  • Risk
  • Weight Gain / drug effects*

Substances

  • Blood Glucose
  • Cholesterol, LDL
  • Dietary Carbohydrates
  • Dietary Fiber
  • Cholesterol