Validation of the omega-3 fatty acid intake measured by a web-based food frequency questionnaire against omega-3 fatty acids in red blood cells in men with prostate cancer

BACKGROUND/OBJECTIVES: The objective of this study was to evaluate the ability of a web-based self-administered food frequency questionnaire (web-FFQ) to assess the omega-3 (ω-3) fatty acids (FAs) intake of men affected with prostate cancer (PCa) against a biomarker. SUBJECTS/METHODS: The study presented herein is a sub-study from a phase II clinical trial. Enrolled patients afflicted with PCa were included in the sub-study analysis if the FA profiles from the red blood cell (RBC) membranes and FA intakes at baseline were both determined at the time of the data analysis (n=60). Spearman's correlation coefficients were calculated to estimate the correlations between FA intakes and their proportions in the RBC membranes. RESULTS: Intakes of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were highly correlated with their respective proportions in the RBC membranes (both rs=0.593, P