A large scale study involving 88,803 premenopausal women (aged 26 to 45) has linked the consumption of red meat to an increased risk of breast cancer in a dose dependent effect. The researchers specifically investigated the association between dietary protein sources in early adulthood and risk of breast cancer over a 20 year follow up study.
Participants completed a survey which had nine categories of intake ranging from “never or less than once per month” to “six or more per day.” The survey included factors such as age, height, weight, race, family history of breast cancer, history of benign breast disease, smoking, menopausal status, hormone and oral contraceptive which were taken into account. Medical records identified 2,830 cases of breast cancer during 20 years of follow-up.
Red meat items included unprocessed red meat (beef, pork, or lamb and hamburger) and processed red meat (such as hot dogs, bacon and sausage); poultry included chicken and turkey; fish included tuna, salmon, mackerel, sardines; legumes included beans, lentils and peas; and nuts.
The researchers evaluated the data statistically to estimate breast cancer risks for women with different diets. They estimated that, for each step-by-step increase in the women’s consumption of red meat, there was a step-by-step increase in the risk of breast cancer over the 20 year study period.
The model estimated that there would be 493 cases of breast cancer over 306,298 person years among women with the lowest intake of red meat. This compared with 553 cases per 31,169 person years among women with the highest intake and associated the statistical risk of breast cancer to red meat consumption to 22%.
The researchers recommended further research and that women should replace protein sources with poultry, fish or legumes.
M. S. Farvid, E. Cho, W. Y. Chen, A. H. Eliassen, W. C. Willett. Dietary protein sources in early adulthood and breast cancer incidence: prospective cohort study. BMJ, 2014; 348 (jun10 3): g3437 DOI: 10.1136/bmj.g3437