Human breast milk bought on the Internet is not always pure human breast milk according to a new American study. Parents purchase human breast milk from the Internet to help supplement their supply, and in some cases the parents are purchasing milk for infants with sensitivities to cows milk or formula.

Researchers tested 102 samples advertised as human breast milk which had been purchased anonymously. They found that 11 samples contained cow DNA and that 10 of these samples were at least 10 per cent cows’ milk.

Previous research in 2013 showed that human milk purchased online grew dangerous bacteria (such as E. coli) leaving the milk unsafe for infant consumption.

A copy of the original research paper published in Pediatrics on April 6, 2015, is available upon request.

Names and affiliations of selected authors

Sarah A. Keim, The Research Institute at Nationwide Children’s Hospital, Ohio, U.S.A.