Context: There is an association between non-alcoholic fatty liver disease (NAFLD) and the polycystic ovary syndrome (PCOS). Marine derived omega-3 fatty acids have favourable effects on cardiovascular risk, and could reduce liver fat in NAFLD. Objective: The primary aim of this study was to examine the effects of omega-3 fatty acids on liver fat in PCOS. The secondary aim was to assess their effects on traditional cardiovascular risk factors.

Design: Randomised, cross-over study. Setting: Tertiary cardiovascular research centre. Subjects: 25 women with PCOS (mean age 32.7 yr, mean body mass index 34.8 kg/m(2)).

Intervention: Comparison of 4g/day of omega-3 fatty acids with placebo over 8 weeks. Main outcome measures: The primary outcome measure was hepatic fat content quantified using proton magnetic resonance spectroscopy. Secondary outcome measures included fasting lipids and blood pressure.

Results: Omega-3 fatty acids significantly decreased liver fat content compared with placebo (10.2(1.1) v 8.4(0.9)%, p=0.022). There was also a reduction in triglycerides (1.19(1.03-1.47) v 1.02(0.93-1.18)mmol/L, p=0.002), systolic blood pressure (124.1(12.1) v 122.3(14.5)mmHg, p=0.018), and diastolic blood pressure (73.2(8.4) v 69.7(8.3)mmHg, p=0.005) with omega-3 fatty acids compared with placebo. Omega-3 fatty acids particularly decreased hepatic fat in women with hepatic steatosis, defined as percentage liver fat >5%, (18.2(11.1) v 14.8(9.3)%, p=0.03).

Conclusions: Omega-3 fatty acid supplementation has a beneficial effect on liver fat content and other cardiovascular risk factors in women with PCOS, including those with hepatic steatosis. Whether this translates into a reduction in cardiometabolic events warrants further study.

keywords: PCOS, polycystic ovary syndrome - omega-3 fatty acids