Table 1

n-3 PUFA and breast cancer risk: Prospective cohort studies.

Year	Country	Subjects	Method of Assessment	n-3/n-6 PUFA Source	BC Risk	Reference
2005	Japan	26,291 women 40–79 years 129 BC cases	FFQ 1	Animal and fish fat, vegetable oil, SFA, MUFA and PUFA	↑ fish fat, EPA + DHA ↓ BC risk	[35]
2003	Singapore	35,298 women 45–74 years 342 BC cases	FFQ	Fish/shellfish, saturated, monounsaturated and polyunsaturated fat	↑ n-3 PUFA from fish/shellfish ↓ BC risk ↑ n-6 PUFA ( low marine n-3) ↑ BC risk	[36]
2010	US	35,016 postmenopausal 50–76 years 880 BC cases	FFQ	Dietary fish oil supplement	↑ fish oil ↓ risk of invasive ductal carcinomas	[40]
2009	France	56,007 women 40–65 years 1650 BC case	FFQ	ALA and n-6 PUFA from fruit, nuts and vegetable oils; Long chain n-3 PUFA from meals	no association between total n-3 and BC risk ↑ ALA ↓BC risk ↑ long chain n-3 PUFA ↓ BC risk (at highest quintile of n-6 PUFA)	[42]
2003	Denmark	23,693 postmenopausal 50–64 years 424 BC cases	FFQ	Fish	↑ intake of fish ↑ ER + BC incidence	[43]
2011	China	72,571 women 40–70 years 712 BC cases	FFQ	Fish, marine-derived n-3 PUFA red meat	↑ n-6/n-3 PUFA ratio ↑ BC risk	[37]

¹ FFQ: food frequency questionnaire; ↑: increase; ↓: decrease.