It’s not your typical viral photo: a collection of bacteria-containing petri dishes. But in the middle of each petri dish is a disc soaked in breast milk—and around each disc, there is a distinctly visible ring where the microbes have died off.
In other words, the image captures the antibacterial power of breast milk in action, and the Internet’s going crazy for it.
The picture was posted on Facebook by Vicky Greene, a first-year biosciences major at South Devon College in the U.K. In the caption, Greene explained that the petri dishes are part of an experiment comparing the effects of two samples of breast milk—one from a mom feeding a 15-month-old, and one from a mom feeding a 3-year-old—on the bacterium M. luteus.
“See that clear bit around the discs—that’s where the proteins in the milk have killed off the bacteria!” she wrote. “It also worked with E. coli and had a fairly good go at MRSA too.” (MRSA stands for methicillin-resistant Staphylococcus aureus, a drug-resistant germ.)
Next Greene plans to repeat her experiment with colostrum, the liquid rich in antibodies that new moms produce before their milk comes in.
Since Greene posted the image on Monday it’s racked up more than 22,000 likes, and 3,000 comments. Greene didn’t say whether she used controls in her experiments—such as samples of infant formula—but some commenters have suggested she include them. One woman pointed out that seeing control samples “would add strength to the image.”
Of course Greene’s project isn’t the first to reveal the bacteria-fighting properties of breast milk. It’s long been known that breast milk contains antibodies that protect babies from infection. And a study published last year found that a protein in breast milk, called lactoferrin, may prevent pneumonia and meningitis in premature newborns.
But there are other claims about breast milk that haven't been conclusively proven by science. An Ohio State University study, published in 2014, looked at families in which one baby was fed formula and the other was breastfed. The researchers found no "breast-is-best" advantage when it came to the intelligence or IQ of children who were given breast milk.
While experts agree that breast milk is the best thing to feed your baby, check out our myths and facts about breastfeeding for more information on the benefits that are supported by science, and those that need more research to confirm one way or the other.