The Association Between Maternal Dietary Intake and the Risk of Heavy Metals in Human Breast Milk in Korea

Heavy metals (HMs) persist in the environment and enter the human body via various pathways. Once stored in adipose tissue, they can be transferred to breast milk, posing risks to infants. Moreover, maternal diet plays a key role in influencing HM levels in breast milk. The aim of this study was to measure the concentration of HMs, including lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As), in the breast milk of Korean mothers, assess their potential health risks, and identify maternal dietary factors influencing HM concentration in breast milk. Survey data on maternal-infant pairs and breast milk samples from 209 healthy lactating mothers were collected between January and March 2023. Trained nurses manually expressed the breast milk to prevent external contamination, and maternal dietary intake was systematically assessed using the 24 h recall method. The concentrations of Pb, Cd, Hg, and As were measured, and a risk assessment was conducted using the estimated daily intake hazard quotient. A multiple linear regression model was employed to evaluate the association between the HMs in breast milk and maternal dietary factors. Cd was detected in 99% of the breast milk samples, and high detection rates were observed for Hg (97%), As (89%), and Pb (79%). Arsenic was the largest contributor to the potential health risks of HM-contaminated breast milk. Positive associations were observed between Pb concentration and legume and seaweed consumption, Cd concentration and vegetable and seaweed consumption, Hg concentration and sugar intake, and As concentration and meat intake. This study highlights that maternal dietary intake is closely linked to HM concentrations in breast milk, and elevated As levels potentially pose health risks to infants. These findings underscore the importance of adopting a healthy diet to reduce HM exposure in breast milk and to promote safer breastfeeding practices.