British Journal of Nutrition

Systematic Review with Meta-Analysis

Dietary intake of n-3 fatty acids and colorectal cancer risk: a meta-analysis of data from 489 000 individuals

Xiao-Jian Shena1, Jun-Dong Zhoua1, Jia-Yi Donga2, Wei-Qun Dinga3 and Jin-Chang Wua1 c1

a1 Department of Radiotherapy, Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, People's Republic of China

a2 Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, People's Republic of China

a3 Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA


Preclinical studies have suggested an anti-colorectal cancer effect of n-3 fatty acids, yet epidemiological studies have reported mixed results. The goal of the present meta-analysis was to examine the association between the dietary intake of n-3 fatty acids and colorectal cancer risk by conducting a meta-analysis of prospective cohort studies. We searched the PubMed database up to February 2012 to identify eligible studies. Either a fixed- or random-effects model was used to obtain a pooled relative risk (RR) comparing the highest intake of n-3 fatty acids with the lowest. We conducted subgroup analyses according to sex, geographic region, length of follow-up, cancer site and type of n-3 fatty acids. We included seven prospective studies in the meta-analysis, comprising 489 465 participants and 4656 incident cases. The pooled RR of colorectal cancer in relation to n-3 fatty acids was 0·98 (95 % CI 0·88, 1·09). The results from subgroup analysis indicated a significant reduced risk of colorectal cancer in relation to n-3 fatty acids among men (RR 0·87, 95 % CI 0·75, 1·00; n 4). No significant association was observed in other subgroups. There was no evidence of publication bias as suggested by Begg's test (P = 0·76) and Egger's test (P = 0·66). The present meta-analysis showed insufficient evidence of a protective effect of n-3 fatty acids on colorectal cancer risk. However, a reduced risk observed in men warrants further investigation.

(Received April 24 2012)

(Revised July 06 2012)

(Accepted July 09 2012)

(Online publication August 20 2012)

Key Words:

  • n-3 Fatty acids;
  • Colorectal cancer;
  • Cohort studies;
  • Meta-analyses


c1 Corresponding author: Dr J.-C. Wu, fax +86 512 62364381, email


  Abbreviations: RR, relative risk