A recent medical study has found that breastfeeding enhances the immune system in women and provides protection against breast cancer, especially the triple-negative type known for its aggressiveness.
Published in Nature and reported by The Guardian, the research shows that breastfeeding activates specialized immune cells known as CD8⁺ T cells, which play a crucial role in defending the body against cancer.

Professor Sherene Loi, a clinical scientist at the Peter MacCallum Cancer Centre in Melbourne, explained that these adaptive immune cells respond not only to viruses and bacteria but also to cancerous cells, emphasizing that women with higher levels of these cells experience better outcomes and stronger immune protection.

Researchers analyzed non-cancerous breast tissues from over 260 women from diverse backgrounds who had undergone breast reduction or preventive surgery. The findings revealed that women who had experienced pregnancy and breastfeeding had higher levels of these protective immune cells, which remain active for more than 30 years after childbirth.

In laboratory experiments using mice, tumors grew much slower in those that had given birth and breastfed compared to those that had not, suggesting that breastfeeding leaves a long-lasting immune imprint.

The study also found that women who breastfed had better recovery rates from triple-negative breast cancer, with their tumors containing a greater number of immune-resistant cells, indicating ongoing immune activity that suppresses tumor growth.

According to the findings, each year of breastfeeding reduces a mother’s lifetime risk of breast cancer by 4%, as both pregnancy and breastfeeding cause lasting biological changes in immune and breast cells that strengthen natural defenses against cancer.