Does a low-fat diet help prevent breast cancer?

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Clinical Inquiries

Does a low-fat diet help prevent breast cancer?

J Fam Pract. 2007 July;56(7):583-584

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References

1. Willett WC. Diet and breast cancer. J Intern Med 2001;249:395-411.

2. Bingham SA, Luben R, Welch A, Wareham N, Khaw KT, Day N. Are imprecise methods obscuring a relation between fat and breast cancer?. Lancet 2003;362:212-214.

3. Mattisson I, Wirfalt E, Wallstrom P, Gullberg B, Olsson H, Berglund G. High fat and alcohol intakes are risk factors of postmenopausal breast cancer: a prospective study from the Malmo diet and cancer cohort. Int J Cancer 2004;110:589-597.

4. Sieri S, Krogh V, Muti P, et al. Fat and Protein Intake and subsequent Breast Cancer risk in Postmenopausal Women. Nutr Cancer 2004;42:10-17.

5. Velie E, Kulldorff M, Schairer C, Block G, Albanes D, Schatzkin A. Dietary fat, fat subtypes, and breast cancer in postmenopausal women: a prospective cohort study. J Natl Cancer Inst 2000;92:833-839.

6. Holmes MD, Hunter DJ, Colditz GA, et al. Association of dietary intake of fat and fatty acids with risk of breast cancer. JAMA 1999;281:914-920.

7. Low-Fat Dietary Pattern and risk of Breast Cancer, Colorectal Cancer, and Cardiovascular Disease: The Women’s Health Initiative randomized Controlled Dietary Modification Trial. Available at: www.whi.org/findings/dm/dm.php. Accessed on June 14, 2007.

8. 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 2003;89:1672-1685.

9. Rock CL. Diet and breast cancer: can dietary factors influence survival? J Mammary Gland Biol Neoplasia 2003;8:119-132.

10. Rowan T, Chlebowski GL, Blackburn CA, et al. Dietary Fat Reduction and Breast Cancer Outcome: Interim Efficacy Results From the Women’s Intervention Nutrition Study. J Natl Cancer Inst 2006;98:1767-1776.

11. Mosca L, Appel LJ, Benjamin EJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women. Circulation 2004;109:672-693.

Since the late 1990s, several meta-analyses, a systematic review of these cohort studies, and the Women’s Health Initiative Randomized Controlled Diet Initiative have largely concluded that there is no difference in breast cancer incidence between women with a low-fat diet (<20% of total calories from fat) and women with average or high-fat diets (>40% total calories from fat).^1,3,6,7

The meta-analysis performed by Boyd et al did find a statistically significant difference, with relative risks ranging from 1.11 for overall to 1.19 for high-saturated-fat diets.⁸ The upper limit of all confidence intervals was no higher than 1.35, however, suggesting a lack of clinical significance. The best-designed studies also evaluated dietary composition with regard to key types of fat (saturated, mono- and poly-unsaturated; animal vs vegetable vs marine) and found no significant differences based on type of fat consumed.¹

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The WHI showed that women with breast cancer who reduced fat intake had a lower hazard ratio for relapse

Preliminary evidence indicates that lowering dietary fat consumption may help with secondary prevention of breast cancer, but no large studies have been performed to date.⁹ Recently, a nested study within the Women’s Intervention Nutrition Study did show that women with breast cancer who decreased their fat intake to a median of 33 g/day had a hazard ratio of 0.76 for relapse over 60 months (compared with controls who ate a median of 51 g/day).¹⁰

Recommendations from others

There are no evidence-based or specific recommendations for the primary prevention of postmenopausal breast cancer for women through dietary fat reduction. In particular, neither the American Academy of Family Physicians, American College of Surgeons, National Institutes of Health, American College of Obstetricians and Gynecologists, American College of Physicians, US Preventive Services Task Force, or the Centers for Disease Control and Prevention provide any guidelines on dietary fat restriction for primary prevention of postmenopausal breast cancer.

The American Heart Association does have guidelines for coronary artery disease prevention for women, which include a low-fat diet.¹¹ The USPSTF has no specific guidelines regarding dietary fat consumption for the general population.

Evidence-based answers from the Family Physicians Inquiries Network

Does a low-fat diet help prevent breast cancer?

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