Background: It is believed that n-3 polyunsaturated fatty acid (PUFA) status is important for cardiovascular health. However, the major sources of the essential dietary PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are fish and fish oil supplements. Limited conversion of α-linoleic acid (ALA), found in plant foods (flaxseeds, walnuts, soya and rape-seed oils), to EPA, DPA (docosapentaenoic acid) and DHA occurs in men (0.2–6% for EPA and DPA, ≤0.05% for DHA) but is greater in younger women (Burdge, 2006). Therefore, n-3 PUFA status may be compromised in individuals not eating fish or fish-oils, compared with fish-eaters. An investigation into n-3 PUFA status and estimated potential conversion of ALA in middle-aged women with different dietary habits in the EPIC-Norfolk population was conducted.