Some women turn their placentas into smoothies, jerky, and even pills, hoping that ingesting the birth organ might ward off post-partum depression, increase milk production, and promote health.
Now reality TV star Kim Kardashian is one of those believers.
"So, I'm really not this holistic person or someone who would have ever considered eating my placenta," Kardashian wrote in a new a blog post, before explaining why she decided to do just that.
Kardashian, who recently gave birth to her second child, decided to try out the trendy home remedy that many new moms swear by — in spite of little to no scientific support.
While we can't say for certain that eating your own placenta is not helpful, there is little reason to think that it could be.
Mark Kristal, a University of Buffalo researcher who has studied the subject, called it "a New Age phenomenon" and told New York Magazine that it is a "fad" and "not based on science." A benefit may be possible, but is essentially completely untested.
There have been only a handful of small studies examining human placenta-eating (what scientists call placentophagy) since 1950, and the results of these have been "inconclusive" at best, noted a recent review of the research by scientists at the Northwestern University Feinberg School of Medicine.
The risks are similarly unknown, though some could exist.
"Because the placenta contains enzymes that perform all of the major processes of metabolism ... and operates as a filtering mechanism as well, environmental toxins directly (filtered) or indirectly ... may render ingested raw afterbirth tissue [placenta] a toxicological, endocrinological, or immunological threat to some women," warned one recent paper on the subject.
The risks and any possible benefits also likely vary depending on how the placenta is being consumed. It's not at all standardized, and a dehydrated, ground up placenta-in-a-pill is not the same as placenta jerky.
Eating placenta "raw seems dangerous. Cooking it would be the safest bacteria wise, but might destroy any potential active ingredient," the gynecologist Dr. Jennifer Gunter wrote, in a blog post earlier this year that cited infection as one likely risk.
"Without studies one can't really say anything including are there even active ingredients?" Dr. Gunter wrote.
—Kim Kardashian West (@KimKardashian) December 14, 2015
"If you expect a therapy will help you it is more likely to do so," Dr. Gunter explained. "Placebos can have an amazing impact, which is a big reason we need studies."
In other words: If we don't compare placenta pills to sugar pills, it's impossible to know if it's something in the placenta that makes some moms feel better, or just the act of taking a pill and expecting to get a boost.
Other animals eat their placentas — and that's without any celebrities telling them to do so, feelings of disgust be damned. But wild mammals are dealing with a different situation than we are.
"If [animals] don't eat the placenta, then scavengers and predators will come around and see or smell the blood," Weill Cornell's Rebecca Baergen told Scientific American. "It's kind of an issue of cleanup for those animals, so they don't leave behind a signature for predators that can prey on the young."
That's not really an issue for Kim Kardashian, or for most moms who seem to be warming to the fad. In fact, a study of 179 different human societies found that placenta-eating was not traditional practice for mothers in any of them.
As Kristal wrote in 2012, if placenta-eating is not something humans do, "we should assume that there must be a good adaptive reason for its elimination."
