Can your diet and lifestyle put heavy metals in your breast milk?

What's actually in it

Breast milk can contain lead, mercury, cadmium, and arsenic. These metals accumulate in a mother's body over her lifetime from food, water, air, and household products. During breastfeeding, stored metals get released into the milk along with all the good stuff. The baby gets both the nutrition and the contaminants.

What the research says

A 2026 review in J Nutr examined what determines how much heavy metal ends up in breast milk. The researchers looked across dozens of studies to identify which maternal factors matter most.

Diet was the biggest factor. Mothers who ate more rice had higher arsenic levels in their milk. Those who ate more large fish, like tuna and swordfish, had more mercury. Smoking added cadmium. Living near industrial areas or using lead-glazed pottery for cooking increased lead levels.

Other factors included age, number of pregnancies, and body weight. Older mothers and those with more pregnancies had accumulated more metals over time. The metals stored in bones and fat get mobilized during breastfeeding, released into the milk as the body draws on its reserves to feed the baby.

None of this means you should stop breastfeeding. Breast milk is still the best food for infants. But you can lower the metal levels by eating a varied diet, avoiding high-mercury fish, filtering your water, and staying away from cigarette smoke.