title: Dietary methionine intake and risk of incident colorectal cancer: a meta-analysis of 8 prospective studies involving 431,029 participants.
abstract: BACKGROUND
  Methionine is one of the key components of one carbon metabolism. Experimental studies indicate that methionine may reduce inflammation-induced colon cancer. However, epidemiologic findings as to whether dietary methionine intake influences colorectal cancer incidence in humans are inconsistent.
  
  
  OBJECTIVE
  To investigate the relationship between dietary methionine intake and risk of colorectal cancer by performing a meta-analysis of prospective studies.
  
  
  METHODS
  Eligible studies were identified by searching PubMed and Embase and by reviewing the bibliographies of the retrieved publications. The summary risk estimates were computed using both a random- effects and a fixed-effects model.
  
  
  RESULTS
  Eight eligible prospective cohort studies involving 431,029 participants and 6,331 colorectal cancer cases were identified. According to the random-effects model, the summary relative risks (RRs) for the highest compared with the lowest intake of methionine were 0.89 (95% confidence interval [CI] = 0.77-1.03) for colorectal cancer, 0.77 (95% CI = 0.64-0.92) for colon cancer, and 0.88 (95% CI = 0.55-1.42) for rectal cancer. In the stratified analysis, a significant inverse association between dietary methionine intake and risk of colorectal cancer was observed in studies with longer follow-up time (RR=0.81, 95% CI= 0.70-0.95), in Western studies (RR= 0.83, 95% CI = 0.73-0.95) and in men (RR = 0.75, 95% CI= 0.57-0.99). We found no indication of publication bias.
  
  
  CONCLUSIONS
  This meta-analysis indicates that dietary methionine intake may be associated with decreased risk of colorectal cancer, especially colon cancer. More prospective studies with long follow-up time are needed to confirm these findings.
authors: Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, Hubei Province, China.
authors: Zhong-Yin
authors: ZY
authors: Zhou
authors: Xin-Yue
authors: XY
authors: Wan
authors: Ji-Wang
authors: JW
authors: Cao
mesh_terms: D002244:Carbon / Q000737:chemistry; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology*; D004032:Diet; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008715:Methionine / Q000737:chemistry*; D011446:Prospective Studies; D012306:Risk
chemical_list: D002244:Carbon; D008715:Methionine