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Nutr J. 2018 Sep 21;17(1):87. doi: 10.1186/s12937-018-0394-2.

Association between whole grain intake and breast cancer risk: a systematic review and meta-analysis of observational studies.

Author information

1
Shenzhen Key Laboratory of Molecular Epidemiology, Shenzhen Center for Disease Control and Prevention, Shenzhen, China.
2
School of Public Health and Primary Care, Faculty of Medicine, School of Public Health, Prince of Wales Hospital, The Chinese University of Hong Kong, Room 508, Shatin, New Territories, Hong Kong, China.
3
Alvin J. Siteman Cancer Center and Department of Surgery, Washington University School of Medicine, St. Louis, USA.
4
Channing Division of Network Medicine, Brigham and Women's Hospital, Harvard Medical School, 181 Longwood Avenue, Boston, MA, 02115, USA. rulla.tamimi@channing.harvard.edu.
5
Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, USA. rulla.tamimi@channing.harvard.edu.
6
School of Public Health and Primary Care, Faculty of Medicine, School of Public Health, Prince of Wales Hospital, The Chinese University of Hong Kong, Room 508, Shatin, New Territories, Hong Kong, China. xuefensu@cuhk.edu.hk.

Abstract

BACKGROUND:

Epidemiological studies have found that high whole grain intake may be associated with a reduced risk of breast cancer. However, the evidence has not been consistent. We conducted a meta-analysis to quantitatively assess the association between whole grain intake and breast cancer risk.

METHODS:

Relevant observational studies were identified by searching PubMed, Embase, Cochrane library databases, and Google Scholar through April 2017. Summary relative risk (RR) estimates were calculated using random-effects meta-analysis.

RESULTS:

A total of 11 studies, including 4 cohort and 7 case-control studies and involving 131,151 participants and 11,589 breast cancer cases, were included in the current meta-analysis. The pooled RR of breast cancer for those with high versus low whole grain intake was 0.84 (95% confidence interval [CI]: 0.74 to 0.96, p = 0.009; I2 = 63.8%, p for heterogeneity = 0.002). Subgroup analysis by study design found a significant inverse association in the case-control studies (RR: 0.69; 95% CI: 0.56 to 0.87, p = 0.001; I2 = 58.2%, p for heterogeneity = 0.026), but not in the cohort studies (RR, 0.96; 95% CI: 0.82 to 1.14, p = 0.69; I2 = 66.7%, p for heterogeneity = 0.029). In addition, stratified analysis suggested that sample size could be a potential source of heterogeneity.

CONCLUSIONS:

Results of the current meta-analysis suggest that high intake of whole grains might be inversely associated with a reduced risk of breast cancer, and the inverse association was only observed in case-control but not cohort studies. More large-scale cohort studies are needed to confirm the inverse association observed.

KEYWORDS:

Breast cancer; Meta-analysis; Observational studies; Whole grain

PMID:
30241536
PMCID:
PMC6201708
DOI:
10.1186/s12937-018-0394-2
[Indexed for MEDLINE]
Free PMC Article

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