Whole-grain consumption and cardiometabolic risk: a meta-analysis of randomized trials.

Abstract

Evidence suggests that higher whole-grain intake is associated with lower cardiometabolic disease risks, but underlying mechanisms remain unclear. Randomized trials evaluating the effects of whole grains on cardiometabolic risk factors were included. Random-effects meta-analyses were used to estimate mean differences (MDs) with 95% confidence intervals (CIs) per 48 g/day increment of whole grains (dry weight; equivalent to ∼90 g or 3 servings of fresh weight). Eighty-seven trials (101 publications) were included. Each 48 g/day whole-grain intake was associated with reductions in body weight (MD: -.20 kg; 95% CI: -.31 to -.09; n = 41), waist circumference (-.22 cm; 95% CI: -.39 to -.06; n = 27), total cholesterol (-.10 mmol/L; 95% CI: -.13 to -.07; n = 54), and interleukin-6 (MD: -.12 pg/mL; 95% CI: -.23 to -.00; n = 12), with high certainty; low-density lipoprotein cholesterol (-.07 mmol/L; 95% CI: -.10 to -.05; n = 52), triglycerides (-.04 mmol/L; 95% CI: -.06 to -.02; n = 52), fasting plasma glucose (-.03 mmol/L; 95% CI: -.06 to -.00; n = 44), and systolic blood pressure (-.82 mmHg; 95% CI: -1.49 to -.15; n = 32), with moderate certainty. Non-linear analyses indicated greatest effects at 60-100 g/day for most outcomes, but at higher intakes (up to 180-220 g/day) for a few outcomes. Whole-grain intake was associated with improvements in multiple cardiometabolic risk factors, with larger effects generally observed at intakes of ∼60-100 g/day. However, the certainty of evidence varied across outcomes, and sparse data at higher intake levels limit firm conclusions regarding dose thresholds.