Human milk is a body fluid just like saliva, blood, and semen.

By Amanda MacMillan
Updated July 28, 2017

A viral Facebook post has raised eyebrows—and turned a lot of people off of bake sales forever—after a mother claims she made brownies for a school function with her own breast milk.

“I didn’t have time to run to the store and didn’t think it was a big deal,” the mom wrote in the post, which was screengrabbed and shared by the Facebook group Sanctimommy. “[S]ome of those kids could use the nutrition let’s be honest,” the woman added.

Other moms found out about the ingredient swap and are “blowing it out of proportion,” the mom wrote, as she asks for advice about what to do now.

Whether this really happened or not has yet to be confirmed, People reports. But the post itself, and the debate it sparked in the comments section, brings up an interesting question. Sure, drinking someone else’s breast milk is kinda weird, and there are definitely ethical issues with sneaking it into baked goods unannounced. But is it safe?

It’s certainly not a good idea, says Sarah Keim, PhD, associate professor of pediatrics in The Ohio State University College of Medicine and of Epidemiology. “Human milk is a body fluid like saliva, blood, or semen, so it can transmit infectious diseases,” says Keim—including HIV and hepatitis C and B. “Human milk can also carry with it any drugs or pharmaceuticals that donor might be taking,” she adds.

But what about the baking process? “High heat theoretically should kill most viruses,” says Keim, “although I’m not aware that anyone has directly tested this for baked goods with human milk.”

The potential for contamination and illness transmission is also why doctors warn against buying breast milk off the Internet. It's marketed to women who can’t make milk themselves for their babies, but also to a subset of adult consumers who drink breast milk for its apparent “superfood” qualities.

“Online forums are replete with posts boasting about the immune, recovery, nutritional, and muscle building benefits of human milk,” wrote the authors of a 2015 editorial in the Journal of the Royal Society of Medicine. “It is purported to lead to ‘gains’ in the gym, to help with erectile dysfunction, to be more digestible, and to contain positive immune building properties.”

But those claims don’t stand up to evidence, the authors wrote; breast milk doesn’t even has as much protein as other milks like cow’s milk, and no studies have shown that drinking it provides adults with any benefits beyond a placebo. (So much for Facebook mom's point about providing kids with much needed nutrition!) The authors also cite research that found detectable bacteria in 93% of samples purchased online.

Keim has studied Internet sales of breast milk as well, and in 2015 published a paper in Pediatrics that found that 11 out of 102 samples sold online as breast milk tested positive for both human and bovine DNA—suggesting the samples were topped off with cow’s milk. Not only is that dishonest, Keim and her colleagues wrote, but it could be dangerous for infants with a dairy allergy or intolerance.

The Food and Drug Administration also recommends against feeding babies breast milk acquired directly from individuals other than a child’s mother. If parents do decide to feed their child human milk from another source, they should “only use milk from a source that has screened its milk donors and taken other precautions to ensure the safety of its milk.” One of those sources is the Human Milk Banking Association of America, which pasteurizes and screens all donor milk for viruses and bacteria.

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But back to this bake-sale scenario, which—if it really did happen—apparently freaked out other parents at the school. Luckily, the overall health risk of eating a small cooked brownie made with breast milk is “probably not super high,” says Keim. “[But] I don’t think anyone wants to eat food that contains someone else’s body fluids,” she adds, “just like you wouldn’t want to eat food someone else has spit in.”

And one more thing, while we’re on the subject: Yes, the consistency of breast milk might be similar enough to cow’s milk that it could technically work in a brownie recipe. But Keim cautions that, to a baby, the two are very different. “Cow’s milk is not appropriate for young infants,” she says.