Dietary α-Linolenic Acid Is Associated with Reduced Risk of Fatal Coronary Heart Disease, but Increased Prostate Cancer Risk: A Meta-Analysis

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Abstract
The objective of this meta-analysis was to estimate quantitatively the associations between intake of α-linolenic acid [ALA, the (n-3) fatty acid in vegetable oils], mortality from heart disease, and the occurrence of prostate cancer in observational studies. We identified 5 prospective cohort studies that reported intake of ALA and mortality from heart disease. We also reviewed data from 3 clinical trials on ALA intake and heart disease. In addition, we identified 9 cohort and case-control studies that reported on the association between ALA intake or blood levels and incidence or prevalence of prostate cancer. We combined risk estimates across studies using a random-effects model. High ALA intake was associated with reduced risk of fatal heart disease in prospective cohort studies (combined relative risk 0.79, 95% CI 0.60–1.04). Three open-label trials also indicated that ALA may protect against heart disease. However, epidemiologic studies also showed an increased risk of prostate cancer in men with a high intake or blood level of ALA (combined relative risk 1.70; 95% CI 1.12–2.58). This meta-analysis shows that consumption of ALA might reduce heart disease mortality. However, the association between high intake of ALA and prostate cancer is of concern and warrants further study.