Whole-grain and blood lipid changes in apparently healthy adults: a systematic review and meta-analysis of randomized controlled studies.
BACKGROUND
Whole grains are recognized for their potential role in preventing cardiovascular diseases; however, results from randomized controlled studies on blood lipids are inconsistent, potentially because of compositional differences between individual grain types for some nutrients, including dietary fiber.


OBJECTIVE
Using a meta-analytic approach, we assessed the effect of whole-grain compared with non-whole-grain foods on changes in total cholesterol (TC), LDL cholesterol, HDL cholesterol, and triglycerides.


METHODS
We conducted a systematic literature search in selected databases. Studies were included if they were randomized controlled comparisons between whole-grain foods and a non-whole-grain control in adults. A total of 6069 articles were screened for eligibility, and data were extracted from 24 studies. Weighted mean differences were calculated, and meta-regression analyses were performed for whole-grain dose, study duration, and baseline TC concentration.


RESULTS
Overall, whole-grain intake lowered LDL cholesterol (weighted difference: -0.09 mmol/L; 95% CI: -0.15, -0.03 mmol/L; P < 0.01) and TC (weighted difference: -0.12 mmol/L; 95% CI: -0.19, -0.05 mmol/L; P < 0.001) compared with the control. Whole-grain oat had the greatest effect on TC (weighted difference: -0.17 mmol/L; 95% CI: -0.10, -0.25 mmol/L; P < 0.001). No effect of whole-grain foods on HDL cholesterol was seen, whereas whole-grain foods tended to lower triglycerides compared with the control (weighted difference: -0.04 mmol/L; 95% CI: -0.08, 0.01; P = 0.10). No association was found between whole-grain dose or baseline TC concentration and any of the outcomes, whereas study duration was positively associated with changes in TC and LDL cholesterol.


CONCLUSIONS
Consumption of whole-grain diets lowers LDL cholesterol and TC, but not HDL cholesterol or triglycerides, compared with consumption of non-whole-grain control diets. Whole-grain oat appears to be the most effective whole grain for lowering cholesterol.
Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Frederiksberg, Denmark; and.
Pernille L B
http://orcid.org/0000-0002-5767-9873
PL
Hollænder
Food Science, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
Alastair B
http://orcid.org/0000-0002-9585-0141
AB
Ross
Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Frederiksberg, Denmark; and mekr@nexs.ku.dk.
Mette
http://orcid.org/0000-0002-0065-8174
M
Kristensen
D000328:Adult; D008076:Cholesterol, HDL / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood*; D004032:Diet; D004043:Dietary Fiber / Q000008:administration & dosage; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D012680:Sensitivity and Specificity; D014280:Triglycerides / Q000097:blood*; D000067348:Whole Grains / Q000737:chemistry*
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D004043:Dietary Fiber; D014280:Triglycerides
LDL cholesterol; cardiovascular disease; cereals; dietary fiber; lipidemia; total cholesterol; whole grains