Dietary Alpha-linolenic Acid is associated with reduced risk of fatal coronary heart disease, but increased prostate cancer risk: A meta-analysis.
Dietary Alpha-linolenic Acid is associated with reduced risk of fatal coronary heart disease, but increased prostate cancer risk: A meta-analysis.
Year: 2004
Authors: I Brouwer, M B Katan, P L Zock.
Publication Name: Am Society for Nutritional Sciences.
Publication Details: Volume 22; Page 919.
Abstract:
A growing body of evidence suggests that ALA intake is inversely associated with mortality from coronary heart disease. Inconsistent results have been published regarding associations between ALA intake, and blood levels of ALA, and occurrence or prevalence of prostate cancer. The objective of this meta-analysis was to quantitatively assess the relationship between ALA intake and both mortality from heart disease and incidence or prevalence of prostate cancer. For inclusion into the meta-analysis, studies had to provide a quantitative estimate of relative risk (RR) and standard error between dietary intake and metabolic parameter. The association between ALA dietary intake and fatal heart disease risk was based upon a meta-analysis of five prospective cohort studies. Results from three randomized clinical trials investigating the effect of ALA intake on heart disease were also reviewed. Nine observational studies and two case-controlled studies which assessed either ALA intake, or blood concentrations of ALA, with incidence or prevalence of prostate cancer were included in this meta-analysis. Prospective studies related to ALA intake and prostate cancer have not been conducted systematically. Data from the prospective studies and clinical trials reviewed provided a strong indication for a positive role of ALA in preventing fatal heart disease (combined relative risk 0.79, 95% CI 0.60-1.04). The data suggested that increasing intake of ALA by 1.2 g/d decreased the risk of fatal CHD by at least 20%. Review of the data pertaining to ALA and prostate cancer yielded heterogeneous results. A positive association was noted between higher ALA intake or blood level of ALA and advanced prostate cancer (combined relative risk 1.70; 95% CI1.1.2-2.58). This meta-analysis found a significant association between ALA intake and blood levels and a reduction in heart disease mortality. Further assessment of the role of ALA in prostate cancer risk is required. Food sources related to enhanced prostate cancer risk require further analysis as meat, dairy and trans fatty acids were associated with ALA in this meta-analysis. In addition, more recent studies have reported negative relationships of ALA with prostate cancer risk. High levels of ALA may not be advisable in men with existing advanced prostate cancer. The very positive protective effect of ALA on fatal CHD would most likely outweigh any negative effects of ALA on advanced prostate cancer considering that more than 40% of CHD patients are less than 65 years of age when diagnosed, whereas over 50% of prostate cancer patients are more than 75 years of age when diagnosed.
