A new prospective study has reported that dietary beta-carotene may reduce the risk of lobular breast cancer and dietary vitamin E may reduce the risk of hormone receptor positive (ER+/PR+) breast cancer, whereas dietary folate may increase the risk of ER+/PR+ breast cancer in postmenopausal women. The study was designed to investigate the associations between vitamin C, vitamin E, folate, and beta-carotene intake from diet and supplements and the risk of postmenopausal breast cancer. Few studies on micronutrients and breast cancer have investigated the associations with the histology (ductal/lobular) and hormone receptor status of the tumors. The study included 26,224 postmenopausal women who provided information concerning diet, supplements and lifestyle through questionnaires. During follow-up, 1,072 cases of breast cancer were diagnosed among the study participants.

No associations were found between total risk of breast cancer and vitamin C, vitamin E, folate, or beta-carotene intake. However, when the results were analyzed according to breast cancer subtypes, some effects were found. Dietary (but not supplemental) beta-carotene had a protective effect against lobular breast cancer, reducing risk by approximately 28%. Dietary vitamin E was associated with lower risk of estrogen receptor positive (ER+) and progesterone positive (PR+) breast cancer. On the other hand, dietary folate was associated with higher risk of ER+/PR+ breast cancer. The authors conclude that while no effect of micronutrients was found on overall risk of postmenopausal breast cancer, the results indicated possible effects of micronutrients in subgroups of breast cancer.