Dietary total fat and fatty acids intake, serum fatty acids and risk of breast cancer: A meta‐analysis of prospective cohort studies

Results from prospective cohort studies on the association between dietary total fat and fatty acids intake and risk of breast cancer remain controversial. Pertinent prospective cohort studies were identified by a search of Embase and PubMed from inception to September 2015. Study‐specific relative risks (RRs) with 95% confidence intervals were pooled using a random‐effect model. Between‐study heterogeneity and publication bias were assessed, and sensitivity analysis was conducted. Twenty‐four independent studies on dietary total fat and fatty acids intake and seven studies on serum fatty acids were included. The pooled RR of breast cancer for the highest vs. lowest category of dietary total fat intake was 1.10 (1.02–1.19); however, no association was observed in studies adjusting for traditional risk factors of breast cancer. No association was observed between animal fat, vegetable fat, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), n‐3 PUFA, n‐6 PUFA, eicosapentaenoic acid, docosahexaenoic acid, alpha‐linolenic acid, oleic acid, linoleic acid and arachidonic acid and risk of breast cancer. The pooled RRs of breast cancer for the highest vs. lowest category of serum SFA, MUFA, PUFA, n‐3 PUFA and n‐6 PUFA were 1.00 (0.78–1.28), 1.41 (0.99–2.03), 0.59 (0.27–1.30), 0.81 (0.60–1.10) and 0.84 (0.60–1.18), respectively. Results from this meta‐analysis suggested that dietary total fat and fatty acids might be not associated with risk of breast cancer. What's new? Whether or not a woman's risk of breast cancer is increased by a high‐fat diet remains unclear. In particular, the results of prospective cohort studies have been inconsistent. In the present meta‐analysis, data from relevant prospective studies were pooled and assessed. After adjusting for known risk factors, neither dietary total fat intake nor fatty acid intake were found to be associated with breast cancer risk. Further investigation is needed, however, to clarify findings from studies in Europe, for which measurement error may have affected assessments, notably for postmenopausal women.