A small but growing market exists on the internet for human breast milk. Now a study finds that buyers should really beware—some purveyors of breast milk appear to be adulterating their product with cow’s milk.

Such bovine contamination is more than just a scam: it can be a health risk for infants who are allergic to or intolerant of cow’s milk. The study, the first to document this milk fraud, is in the journal Pediatrics. (Sarah A. Keim et al, Cow’s Milk Contamination of Human Milk Purchased via the Internet)

Researchers purchased 102 samples of supposed human breast milk online. Tests found that ten of these samples had enough bovine DNA to indicate that at least 10% of the milk in the sample actually came from cows. 

Human milk is an ideal source of nutrients for infants—when it’s safe. Prior studies on breast milk purchased online have revealed dangerous amounts of bacterial growth that make it unsuitable for infant consumption. Since no one typically screens these internet-sold milk products for pathogens or other contamination it’s up to consumers to protect themselves. Some human milk banks do voluntarily screen their products. So it’s best to check with local departments of health to find safe products.

—Dina Fine Maron 

[The above text is a transcript of this podcast.]