Objective: Prior studies on linoleic acid, the predominant n-6 fatty acid, and breast cancer risk have generated inconsistent results. We performed a meta-analysis to summarize the evidence regarding the relationship of dietary and serum linoleic acid with breast cancer risk.
Design: Pertinent studies were identified by a search of PubMed and EMBASE. The fixed- or random-effect pooled measure was selected based on between-study heterogeneity.
Results: Eight prospective cohort studies and four prospective nested case-control studies, involving 10 410 breast cancer events from 358 955 adult females across different countries, were included in present study. Compared with the lowest level of linoleic acid, the pooled relative risk (RR; 95 % CI) of breast cancer was 0·98 (0·93, 1·04) for the highest level of linoleic acid. The pooled RR (95 % CI) for dietary and serum linoleic acid were 0·99 (0·92, 1·06) and 0·98 (0·88, 1·08), respectively. The RR (95 % CI) of breast cancer was 0·97 (0·91, 1·04), 0·95 (0·85, 1·07), 0·96 (0·86, 1·07), 0·98 (0·87, 1·10) and 0·99 (0·85, 1·14) for linoleic acid intake of 5, 10, 15, 20 and 25 g/d, respectively. The risk of breast cancer decreased by 1 % (RR=0·99; 95 % CI 0·93, 1·05) for every 10 g/d increment in linoleic acid intake.
Conclusions: This meta-analysis indicated that both dietary linoleic acid intake and serum linoleic acid level were associated with decreased risk of breast cancer, although none of the associations were statistically significant. Further investigations are warranted.
Keywords: Diet; Epidemiology; Gastric cancer.