Consumption of garlic and risk of colorectal cancer: an updated meta-analysis of prospective studies.
OBJECTIVE
To conduct an updated meta-analysis of prospective studies addressing the association between garlic consumption and colorectal cancer.


METHODS
Eligible cohort studies were identified by searching MEDLINE (PubMed) and screening the references of related articles published up to October 2013. Meta-analyses were conducted for colorectal cancer in relation to consumption of raw and cooked (RC) garlic and garlic supplements, separately. The summary relative risks (RR) with 95%CI were calculated using fixed-effects or random-effects model depending on the heterogeneity among studies.


RESULTS
A total of 5 prospective cohort studies were identified. In contrast to the previous meta-analysis, no significant associations were found between consumption of RC garlic (RR: 1.06; 95%CI: 0.95-1.19) or garlic supplements (RR: 1.12; 95%CI: 0.96-1.31) and risk of colorectal cancer. A non-significant protective effect of garlic supplement intake against colorectal cancer was observed in females (RR: 0.84; 95%CI: 0.64-1.11), but the opposite was the case in males (RR: 1.24; 95%CI: 0.96-1.59).


CONCLUSIONS
Consumption of RC garlic or garlic supplements is not significantly associated with reduced colorectal cancer risk.
Ji-Yi Hu, Yi-Wang Hu, Jiao-Jiao Zhou, Meng-Wen Zhang, Dan Li, Shu Zheng, Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
Ji-Yi
JY
Hu
Ji-Yi Hu, Yi-Wang Hu, Jiao-Jiao Zhou, Meng-Wen Zhang, Dan Li, Shu Zheng, Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
Yi-Wang
YW
Hu
Ji-Yi Hu, Yi-Wang Hu, Jiao-Jiao Zhou, Meng-Wen Zhang, Dan Li, Shu Zheng, Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
Jiao-Jiao
JJ
Zhou
Ji-Yi Hu, Yi-Wang Hu, Jiao-Jiao Zhou, Meng-Wen Zhang, Dan Li, Shu Zheng, Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
Meng-Wen
MW
Zhang
Ji-Yi Hu, Yi-Wang Hu, Jiao-Jiao Zhou, Meng-Wen Zhang, Dan Li, Shu Zheng, Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
Dan
D
Li
Ji-Yi Hu, Yi-Wang Hu, Jiao-Jiao Zhou, Meng-Wen Zhang, Dan Li, Shu Zheng, Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
Shu
S
Zheng
D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D005737:Garlic; D006801:Humans; D008297:Male; D011446:Prospective Studies; D065840:Protective Factors; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors
Cancer prevention; Colorectal cancer; Garlic; Garlic supplement; Meta-analysis