Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies.
OBJECTIVE
To quantify the dose-response relation between consumption of whole grain and specific types of grains and the risk of cardiovascular disease, total cancer, and all cause and cause specific mortality.


METHODS
PubMed and Embase searched up to 3 April 2016.


METHODS
Prospective studies reporting adjusted relative risk estimates for the association between intake of whole grains or specific types of grains and cardiovascular disease, total cancer, all cause or cause specific mortality.


RESULTS
Summary relative risks and 95% confidence intervals calculated with a random effects model.


RESULTS
45 studies (64 publications) were included. The summary relative risks per 90 g/day increase in whole grain intake (90 g is equivalent to three servings-for example, two slices of bread and one bowl of cereal or one and a half pieces of pita bread made from whole grains) was 0.81 (95% confidence interval 0.75 to 0.87; I(2)=9%, n=7 studies) for coronary heart disease, 0.88 (0.75 to 1.03; I(2)=56%, n=6) for stroke, and 0.78 (0.73 to 0.85; I(2)=40%, n=10) for cardiovascular disease, with similar results when studies were stratified by whether the outcome was incidence or mortality. The relative risks for morality were 0.85 (0.80 to 0.91; I(2)=37%, n=6) for total cancer, 0.83 (0.77 to 0.90; I(2)=83%, n=11) for all causes, 0.78 (0.70 to 0.87; I(2)=0%, n=4) for respiratory disease, 0.49 (0.23 to 1.05; I(2)=85%, n=4) for diabetes, 0.74 (0.56 to 0.96; I(2)=0%, n=3) for infectious diseases, 1.15 (0.66 to 2.02; I(2)=79%, n=2) for diseases of the nervous system disease, and 0.78 (0.75 to 0.82; I(2)=0%, n=5) for all non-cardiovascular, non-cancer causes. Reductions in risk were observed up to an intake of 210-225 g/day (seven to seven and a half servings per day) for most of the outcomes. Intakes of specific types of whole grains including whole grain bread, whole grain breakfast cereals, and added bran, as well as total bread and total breakfast cereals were also associated with reduced risks of cardiovascular disease and/or all cause mortality, but there was little evidence of an association with refined grains, white rice, total rice, or total grains.


CONCLUSIONS
This meta-analysis provides further evidence that whole grain intake is associated with a reduced risk of coronary heart disease, cardiovascular disease, and total cancer, and mortality from all causes, respiratory diseases, infectious diseases, diabetes, and all non-cardiovascular, non-cancer causes. These findings support dietary guidelines that recommend increased intake of whole grain to reduce the risk of chronic diseases and premature mortality.
Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
Dagfinn
D
Aune
Department of Nutrition, Harvard T H Chan School of Public Health, Boston, MA, USA.
NaNa
N
Keum
Department of Nutrition, Harvard T H Chan School of Public Health, Boston, MA, USA Department of Epidemiology, Harvard T H Chan School of Public Health, Boston, MA, USA Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
Edward
E
Giovannucci
Centre for International Health, Department of Global Public Health and Primary Care and Department of Clinical Dentistry, University of Bergen, Bergen, Norway.
Lars T
LT
Fadnes
The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Paolo
P
Boffetta
Biostatistics Unit, Centre for Epidemiology and Biostatistics, University of Leeds, Leeds, UK.
Darren C
DC
Greenwood
Section of Preventive Cardiology, Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital Ullevål, Oslo, Norway.
Serena
S
Tonstad
Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
Lars J
LJ
Vatten
Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
Elio
E
Riboli
Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
Teresa
T
Norat
D002318:Cardiovascular Diseases / Q000401:mortality*; D002423:Cause of Death; D004032:Diet; D006801:Humans; D009369:Neoplasms / Q000401:mortality*; D011446:Prospective Studies; D012307:Risk Factors; D000067348:Whole Grains