Meat, Eggs, or Dairy Intake Not Consistently Linked to Risk for Breast Cancer

Laurie Barclay, MD

June 18, 2009

June 18, 2009 — Intakes of meat, eggs, or dairy products are not consistently linked to risks for breast cancer, according to the results of a prospective study reported ahead of print in the June 2 issue of the American Journal of Clinical Nutrition.

"Meat, eggs, and dairy products — prominent features of the Western diet — have been consistently associated with increased breast cancer incidence and mortality in ecological studies; moreover, there has been an ecological trend of increasing breast cancer mortality coincident with the increase in consumption of animal products that occurred after World War II," write Valeria Pala, from Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy, and colleagues. "The 2007 World Cancer Research Fund report concluded that observational epidemiologic studies do not consistently implicate consumption of any animal food in breast cancer risk."

Using data from the European Prospective Investigation into Cancer and Nutrition, the investigators studied the association of meat, egg, and dairy intake with breast cancer risk among 319,826 women who provided dietary information between 1992 and 2003. Multivariate Cox proportional hazard models allowed estimation of disease hazard ratios (HRs).

During median follow-up of 8.8 years, 7119 cases of breast cancer were diagnosed. There was no consistent association between the risk for breast cancer and dietary intake of any of the food groups studied, with use of either categoric or continuous exposure variable models.

In the categoric model, high intake of processed meat was linked to a small increase in breast cancer risk (HR for highest vs lowest quintile, 1.10; 95% confidence interval [CI], 1.00 - 1.20; P for trend = .07). In premenopausal women only, subgroup analyses suggested an association of breast cancer risk with butter consumption (HR for highest vs lowest quintile, 1.28; 95% CI, 1.06 - 1.53; P for trend = .21).

Findings for red meat intake (beef, veal, pork, and lamb) were heterogeneous between countries (Q statistic = 18.03; P = .05), which was explained (P = .023) by the proportion of meat cooked at high temperature (eg, frying, deep frying, roasting, barbecuing, and grilling).

Limitations of this study include possible errors generated by differences in the dietary assessment, collection of dietary information only at baseline, and lack of information on early-life eating habits of participants.

"We have not consistently identified intakes of meat, eggs, or dairy products as risk factors for breast cancer," the study authors write. "Future studies should investigate the possible role of high-temperature cooking in the relation of red meat intake with breast cancer risk."

Funding for this study was provided by a large number of international research foundations, as detailed in the original article. The study authors have disclosed no relevant financial relationships.

Am J Clin Nutr. Published online June 2, 2009.

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