Presented By
Getty Images

Ever since the FDA warned women that buying breast milk online came with certain serious health and adulteration risks, research about the Internet breast-milk market has been backing up the warnings. Now, a new study published in the journal Pediatrics finds that 10% of breast milk samples bought online are mixed with cow’s milk.

The research team bought 102 bottles of breast milk online, then analyzed the samples for human DNA or bovine DNA from cows. While all the samples had human DNA, 11 of the samples, or 10%, also contained cow DNA.

“We think the [online-purchased breast milk] people would have in their household would be cow’s milk you can get from a carton at the store or infant formula. Most baby formula is made from cow’s milk,” says Dr. Sarah Keim, principal investigator at Nationwide Children’s Hospital in Columbus, Ohio. “Both of those substances would look a lot like human milk.”

MORE: I Bullied Myself Into Breastfeeding

The researchers found far more than trace amounts of cow DNA, suggesting that the adulteration wasn’t the result of accidental contamination—the kind that might occur after re-using a container that had once held cow’s milk, for example. The adulterated samples had enough bovine DNA that they could realistically contain half breast milk, half cow’s milk from the carton, Keim says. One of the samples was almost half breast milk, half infant formula.

Women pay a premium for breast milk online—sometimes $2 an ounce, Keim says—which makes it a prime target for fraud. Adulterating and diluting liquids is easy to get away with; in fact, alcohol was the most adulterated product in a recent global food fraud investigation by Interpol.

Next, the team hopes to look at some of the other risks the FDA warns against, like illicit drugs that could lurk in the Internet-sold milk.

The growing online breast milk market is almost wholly unregulated, according to an editorial in The BMJ last month, which cited Keim’s 2013 study that found 74% of Internet milk samples had growth of Gram-negative bacteria, the kind resistant to multiple drugs.

More Must-Reads From TIME

Write to Mandy Oaklander at

You May Also Like