Dietary fat and breast cancer risk
This summary table contains detailed information about research studies. Summary tables are a useful way to look at the science behind many breast cancer guidelines and recommendations. However, to get the most out of the tables, it’s important to understand some key concepts. Learn how to read a research table.
Introduction: Eating a high-fat diet as an adult appears to have little, if any, impact on breast cancer risk. Studies have found no link between eating a diet high in total fat and breast cancer risk.
Although total fat doesn’t appear to increase breast cancer risk, the type of fat in your diet may be important. This topic is under study.
Dietary fat during the teen years
Eating a high-fat diet during the teen years may play a role in breast cancer.
Some findings show women who ate a diet high in total fat during their teen years had an increased risk of breast cancer before menopause compared to women who at a diet low in total fat during their teen years .
Learn more about dietary fat and breast cancer risk.
Learn about the strengths and weaknesses of different types of studies.
Study selection criteria: Randomized controlled trials with at least 500 breast cancer cases, prospective cohort studies with at least 500 breast cancer cases, pooled analyses and meta-analyses.
Table note: Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.
Study Population (number of participants)
Relative Risk of Breast Cancer in Women Who Ate a High-Fat Diet Compared to Women Who Did Not, by Type of Fat, RR (95% CI)
Randomized controlled trials
Women’s Health Initiative 
Prospective cohort studies
EPIC Nutrition and Cancer Study 
Multiethnic Cohort Study 
Nurses’ Health Study [5-6]
NIH-AARP Diet and Health Study 
Nurses’ Health Study II 
Swedish Women’s Lifestyle and Health Cohort 
VITAL study 
Swedish Mammography Screening Cohort 
NutriNet-Santé Cohort 
Canadian National Breast Screening Study 
Pooled and meta-analyses
Boyd et al. 
Smith-Warner et al. 
UK Dietary Cohort Consortium 
Turner et al. 
25 cohort studies
19 cohort studies
16 cohort studies
Cao et al. 
20 cohort studies
17 cohort studies
Alexander et al. 
8 cohort studies
* Includes 8½ years of intervention and 11 years of post-intervention follow-up
† Postmenopausal women only
‡ Relative risk per 5 percent increase in dietary fat intake
§ Relative risk among women over 50 was 0.45 (0.25-0.99)
║ Combined cohort study results
¶ Animal fat only
- Linos E, Willett WC, Cho E, Frazier L. Adolescent diet in relation to breast cancer risk among premenopausal women. Cancer Epidemiol Biomarkers Prev. 19(3):689-96, 2010.
- Chlebowski RT, Aragaki AK, Anderson GL, et al. for the Women’s Health Initiative. Dietary modification and breast cancer mortality: long-term follow-up of the Women’s Health Initiative Randomized Trial. J Clin Oncol. 38(13):1419-1428, 2020.
- Sieri S, Chiodini P, Agnoli C, et al. Dietary fat intake and development of specific breast cancer subtypes. J Natl Cancer Inst. 106(5), 2014.
- Park SY, Kolonel LN, Henderson BE, Wilkens LR. Dietary fat and breast cancer in postmenopausal women according to ethnicity and hormone receptor status: the Multiethnic Cohort Study. Cancer Prev Res (Phila). 5(2):216-28, 2012.
- Kim EH, Willett WC, Colditz GA, et al. Dietary fat and risk of postmenopausal breast cancer in a 20-year follow-up. Am J Epidemiol. 164(10):990-7, 2006.
- Byrne C, Rockett H, Holmes MD. Dietary fat, fat subtypes, and breast cancer risk: lack of an association among postmenopausal women with no history of benign breast disease. Cancer Epidemiol Biomarkers Prev. 11(3):261-5, 2002.
- Thiébaut ACM, Kipnis V, Chang SC, et al. Dietary fat and postmenopausal invasive breast cancer in the National Institutes of Health-AARP Diet and Health Study cohort. J Natl Cancer Inst. 99(6):451-62, 2007.
- Farvid MS, Cho E, Chen WY, Eliassen AH, Willett WC. Premenopausal dietary fat in relation to pre- and post-menopausal breast cancer. Breast Cancer Res Treat. 145(1):255-65, 2014.
- Löf M, Sandin S, Lagiou P, et al. Dietary fat and breast cancer risk in the Swedish women’s lifestyle and health cohort. Br J Cancer. 97(11):1570-6, 2007.
- Sczaniecka AK, Brasky TM, Lampe JW, Patterson RE, White E. Dietary intake of specific fatty acids and breast cancer risk among postmenopausal women in the VITAL cohort. Nutr Cancer. 64(8):1131-42, 2012.
- Wolk A, Bergström R, Hunter D, et al. A prospective study of association of monounsaturated fat and other types of fat with risk of breast cancer. Arch Intern Med. 158(1):41-5, 1998.
- Sellem L, Srour B, Guéraud F, et al. Saturated, mono- and polyunsaturated fatty acid intake and cancer risk: results from the French prospective cohort NutriNet-Santé. Eur J Nutr. 58(4):1515-1527, 2019.
- Howe GR, Friedenreich CM, Jain M, Miller AB. A cohort study of fat intake and risk of breast cancer. J Natl Cancer Inst. 83:336-340, 1991.
- Boyd NF, Stone J, Vogt KN, Connelly BS, Martin LJ, Minkin S. Dietary fat and breast cancer risk revisited: a meta-analysis of the published literature. Br J Cancer. 89(9):1672-85, 2003.
- Smith-Warner SA, Speigelman D, Adami HO, et al. Types of dietary fat and breast cancer: a pooled analysis of cohort studies. Int J Cancer. 92:767-774, 2001.
- Key TJ, Appleby PN, Cairns BJ, et al. Dietary fat and breast cancer: comparison of results from food diaries and food-frequency questionnaires in the UK Dietary Cohort Consortium. Am J Clin Nutr. 94(4):1043-52, 2011.
- Turner LB. A meta-analysis of fat intake, reproduction, and breast cancer risk: an evolutionary perspective. Am J Hum Biol. 23(5):601-8, 2011.
- Cao Y, Hou L, Wang W. Dietary total fat and fatty acids intake, serum fatty acids and risk of breast cancer: A meta-analysis of prospective cohort studies. Int J Cancer. 138(8):1894-904, 2016.
- Alexander DD, Morimoto LM, Mink PJ, Lowe KA. Summary and meta-analysis of prospective studies of animal fat intake and breast cancer. Nutr Res Rev. 23(1):169-79, 2010.