Researchers examined the association dietary protein sources in early adulthood and risk of breast cancer.
The study was a prospective cohort study – A prospective cohort study follows over time a group of similar individuals (cohorts) who differ with respect to certain factors under study, to determine how these factors affect rates of a certain outcome.
The study was based on data from nearly 90,000 premenopausal women from the Nurses’ Health Study II who completed a questionnaire on diet in 1991.
2830 women developed invasive breast cancer cancer during 20 years of follow-up.
The study found that higher intake of red meat was associated with an increased risk of breast cancer overall.
However, higher intakes of poultry, fish, eggs, legumes, and nuts were not related to breast cancer overall.
The recommendation from this study is very clear: restrict consumption of red meat, especially during the teenage and early adult years.
Replace red meat with a combination of legumes, poultry, nuts and fish. We recommend tofu and tempeh. Compounds found in soy, known as isoflavones, have additional anticancer properties. Some people are concerned about possible negative effects of soy on the thyroid gland. As long as you are not iodine deficient, soy has no negative effect on the thyroid.
Cancer risk reduction
Substituting one serving per day of legumes for one serving of red meat was associated with a 15% lower risk of breast cancer among all women and a 19% lower risk among premenopausal women.
Also, substituting one serving per day of poultry for one serving of red meat was associated with a 17% lower risk of breast cancer overall and a 24% lower risk of postmenopausal breast cancer. We of course recommend free range, organic chicken to avoid cruelty and hormones.
Furthermore, substituting one serving of combined legumes, nuts, poultry, and fish for one serving of red meat was associated with a 14% lower risk of breast cancer overall and premenopausal breast cancer.
Farvid Maryam S, Cho Eunyoung, Chen Wendy Y,Eliassen A Heather, Willett Walter C. Dietary protein sources in early adulthood and breast cancer incidence: prospective cohort study BMJ 2014;348:g3437