The aim of this study was to conduct a randomized, double-blind and placebo-controlled study to investigate the effects of D-004, a lipid extract of the Roystonea regia fruit that prevents testosterone- and phenylepinephrine-induced prostate hyperplasia in rodents, on plasma oxidative markers in healthy men. We enrolled male volunteers (20-55 years) in good health and without lower urinary tract symptoms. Thirty-four eligible participants were randomized to placebo or D-004 (320 mg) capsules administered daily for 6 weeks. An interim check-up and a final visit were conducted after 3 and 6 weeks of therapy, respectively. Physical examinations were performed at each visit, and laboratory tests were performed at baseline and at treatment completion. Oxidative variables included plasma malondialdehyde (MDA), total hydroxyperoxides (TOH), sulphydryl (SH) groups and total antioxidant status (TAS). We assessed treatment compliance and addressed adverse experiences (AEs) at weeks 3 and 6. At week 6, with D-004, the mean reductions of plasma MDA (26.7%), TOH (18.8%) and SH groups (31.6%), and the mean increase of TAS (35.3%) were significantly different from those of placebo (P<0.001 for plasma TAS, P<0.0001 for all other comparisons). D-004 did not differ from the placebo in safety indicators. There were two withdrawals (both in the D-004 group), with one due to dyspepsia (the only AE during the trial). In conclusion, D-004 displayed antioxidant effects on plasma oxidative markers in healthy men, which was consistent with findings from laboratory experimental studies.