We hypothesise that fish oils will have a beneficial effect on cardiometabolic parameters in women with PCOS. The purpose of this study therefore is to examine the effects of fish oils on blood pressure, heart rate variability and liver fat content in obese women with the polycystic ovary syndrome.

The prevalence of abnormalities of blood pressure (ABP), variability of heart rate (HRV) and liver fat content is increased in women with the polycystic ovary syndrome (PCOS). We hypothesise that fish oils will have a beneficial effect on these endpoints and other cardiometabolic parameters such as cholesterol and liver function in women with PCOS. This crossover study of 40 obese women with PCOS will therefore examine the effects of fish oils on the above parameters compared with placebo (olive oil). Subjects with PCOS who have participated in previous studies with this research group will be approached for recruitment, as will eligible subjects within the endocrine clinics of the chief and co-investigators.

Inclusion Criteria:

• Overweight/obese women with PCOS as per 1990 NIH criteria (see below)
• Non-smokers
• Age>18 years, premenopausal
• Acceptable to have/be on treatment for type 2 diabetes mellitus and/or dyslipidaemia
• Acceptable to be taking the oral contraceptive pill

Exclusion Criteria:

• Uncontrolled hypertension (BP>160/100mmHg)
• Known co-morbidities including liver or renal disease
• Already taking fish oil supplements
• Other intercurrent illness (major surgery, CV event)
• Smokers
• Alcohol intake >20g/day
• Pregnancy
• Any metallic implant (contraindication for MRI).