Non-pregnant, non-lactating women aged 18+ were recruited by way of posters, to take part in a dietary intervention study that was examining the effects of dietary fat level and fat type on risk factors associated with breast cancer. Women who were normally menstruating, consumed either their habitual diet or a low-fat diet for three menstrual cycles, along with a supplement containing 1.2 g DHA+EPA /day. This was followed by a 3-menstrual cycle washout, where the habitual diet was consumed without a supplement. Subsequently the participants consumed the other diet (either low-fat or habitual) for a further 3 menstrual cycles with the 1.2 g DHA/EPA supplement. Blood, urine and nipple aspirate fluid were collected at the beginning and end of each intervention period and analyzed for a variety of biomarkers. Diet records were collected continuously over the entire study period and periodic 7-day records examined for collection of detailed nutrition information. Anthropometry was completed at each study visit, and nutritional counselling provided throughout.