Differences in plasma and nipple aspirate carotenoid by lactation status.

Background: Dietary antioxidants, such as provitamin A carotenoid, have a protective effect against breast cancer. The transport of carotenoid from the blood into the breast microenvironment may be enhanced by lactation.

Objective: To examine the association between plasma and nipple aspirate carotenoid levels by lactation and post-wean status.

Methods: The sample consisted of 43 women, ages 18-45, who were at least 12 months postpartum. Women who had breastfed their last infant were at least 3 months post-wean. Women collected breast fluid every other day for 17 days and had a venipuncture for total nipple aspirate and plasma carotenoid, and completed a written health assessment.

Results: The association between plasma and nipple aspirate carotenoid levels was significant for breastfeeding women (r =.39, p=.03), but not for non-breastfeeding women (r =.31, p =.27). However, while the association between plasma and nipple aspirate carotenoid levels was significant for women at or less than 9 months post-wean (r =.65, p = .01), the effect for women after 9 months post-wean (r = .21, p =.45) was not significant.

Conclusion: Lactation may be protective by enhancing the delivery of chemopreventive substances available in the blood to the cell level of the breast, even after breast involution has occurred post lactation.