Effective medical treatments of infertile men with idiopathic oligoasthenoteratospermia (OAT) have yet to be determined.

This study considered two major aims: (i) to measure the changes in semen parameters, omega-3 fatty acids (FA) compositions and anti-oxidant activity; (ii) to determine if the administration of omega-3 FA affect semen quality in infertile men with OAT.

Two hundred thirty-eight infertile men with idiopathic OAT were randomised to eicosapentaenoic (EPA) and docosahexaenoic acids (DHA), 1.84 g per day (EPAX 5500TG; Lysaker, Norway), or placebo for 32 weeks. The semen parameters were assessed according to WHO criteria, and the EPA and DHA concentrations were determined in red blood cells (RBCs), seminal plasma and sperm cells at baseline and 32-week treatment period. Of randomised subjects, 211 (88.7%) completed the full 32-week randomisation period. The anti-oxidant status of seminal plasma was also evaluated by measuring the superoxide dismutase (SOD) and catalase-like activity.

In the total group of participants, all EPA and DHA levels in RBC, and seminal plasma, were statistically significantly correlated with those in spermatozoa (both P = 0.001). A significant improvement of sperm cell total count (from 38.7 ± 8.7 ' 10⁶ to 61.7 ± 11.2 ' 10⁶, P = 0.001) and sperm cell concentration (from 15.6 ± 4.1 ' 10⁶ per ml to 28.7 ± 4.4 ' 10⁶ per ml, P = 0.001) was observed in the omega-3 group.

A significant positive correlation was found between the EPA and DHA in seminal plasma and the semen parameters. Seminal plasma EPA and DHA concentrations were positively correlated with seminal plasma SOD-like and catalase-like activity (both P = 0.001). In seminal plasma, both SOD-like and catalase-like activity were positively correlated with sperm count, sperm motility, and sperm morphology.

Oligoasthenoteratospermic men with low levels of EPA and DHA may benefit from omega-3 FA supplementation. Further studies are warranted to shed more light on this important issue.