Dietary intake and biomarkers of linoleic acid and risk of prostate cancer in men: A systematic review and dose-response meta-analysis of prospective cohort studies

Findings on the association of dietary intake and tissue biomarkers of linoleic acid (LA) with the risk of prostate cancer are conflicting. Also, no meta-analysis summarized available findings in this regard. Therefore, the current systematic review and dose-response meta-analysis were done to summarize the findings of prospective cohort studies that assessed dietary intake and tissue biomarkers of LA in relation to prostate cancer risk in adults. We conducted a systematic search using online databases, including PubMed, Scopus, and ISI Web of Science, to identify eligible articles published up to January 2023. We included prospective cohort studies that examined the associations of dietary intake and tissue biomarkers of LA with the risk of prostate cancer (total, advanced, and fatal prostate cancer). Summary relative risks (RR) and 95% confidence intervals (CI) were calculated for the highest versus lowest intakes/tissue levels of LA using a fixed-effects model. Also, linear and non-linear dose-response analyses were conducted. In total, 15 prospective cohort studies were included. These studies recruited a total sample size of 511,622 participants with an age range of ≥18 years. During the follow-up periods ranging from 5 to 21 years, 39,993 cases of prostate cancer, 5,929 cases of advanced prostate cancer, and 1,661 cases of fatal prostate cancer were detected. In the meta-analysis, we found that higher tissue levels of LA were associated with a reduced risk of prostate cancer (RR: 0.86, 95% CI: 0.77-0.96) so that in the dose-response analysis, each 5% increase in levels of LA was associated with a 14% lower risk of prostate cancer. Such a significant association was not seen for advanced prostate cancer (RR: 0.86, 95% CI: 0.65-1.13). Also, we found no significant association between dietary intake of LA and risk of total (RR:1.00, 95% CI: 0.97-1.04), advanced (RR: 0.98, 95% CI: 0.90-1.07), and fatal prostate cancer (RR: 0.97, 95% CI: 0.83-1.13). Our findings support the protective association between tissue levels of LA and the risk of prostate cancer in men.