According to the study "Being Breastfed in Infancy and Risk of Colorectal Cancer and Precursor Lesions" published in Clinical Gastroenterology and Hepatology, rates of young-onset colorectal cancer have been on the rise since the early 1990s.

This study, led by researchers at Dana-Farber Cancer Institute, investigated potential links between being breastfed as an infant and having colorectal cancer later in life. The team evaluated data collected by the Nurses' Health Study and the Nurses' Health Study II for 158,696 women aged 27-93 years.

The study found that having been breastfed as an infant was associated with a 23% increased risk of colorectal cancer later in life. Among people in the Nurses' Health Study II, a study that enrolled a younger group of female nurses born between 1947 and 1964, having been breastfed was associated with increased risk of high-risk colorectal adenomas before age 50 and colorectal cancer before age 55. Further research is required to understand the underlying mechanisms.

These findings should not discourage breastfeeding, which offers numerous advantages for both mothers and infants. Rather, this study underscores a need for research into the biological mechanisms underlying the association between being breastfed and colorectal cancer risk, including the role of the microbiome or other pathways as well as the formulation of potential risk-reducing interventions.