Should new mothers be eating their afterbirth? Many moms may be asking themselves that question, now that Kim Kardashian has made her placentophagy public.

Many — including a growing subset of celebrity moms like Kardashian West — say the answer is yes, praising potential health benefits like improvement in mood, nutritional fortitude, increased energy and better milk production.

"I heard so many stories when I was pregnant with North of moms who never ate their placenta with their first baby and then had postpartum depression," Kardashian West wrote in a blog (well, in her personal app), "but then when they took the pills with their second baby, they did not suffer from depression! So I thought, why not try it? What do I have to lose?"

But according to a recent paper examining all previous studies on the subject, there isn't any real evidence to support those potential benefits. Perhaps more importantly, there's no research on what the potential risks of consuming a human placenta might be.

The study, published earlier this year in Archives of Women's Mental Health, came about when author Crystal Clark had some patients ask her opinion on the practice. Clark is assistant professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and a psychiatrist specializing in reproduction-related mood disorders at Northwestern's Asher Center for the Study and Treatment of Depressive Disorders, and her patients wanted to know if placental capsules — ostensibly taken to improve their mood — would interact with the antidepressants Clark had prescribed them.

"I found myself really confused by the question," Clark said.

She — and her colleagues in obstetrics, who she asked about the practice — knew of no clinical studies on this.

"Many of my colleagues in obstetrics were more aware of it than I was," she said. "They'd seen it talked about on TV, so they knew it was happening, but they didn't think any of their own patients were doing it. That was interesting, since I knew for a fact that some of their patients were considering it."

That got Clark thinking: Where were the women getting their information on placentophagy, and what was the evidence in support of it? When she went looking, there wasn't much to be found. Her attempt to have an informed conversation with her patients led to a full-blown study of all the available literature. And Clark's conclusion is that it's all bunk.

In a post on her blog, actress Mayim Bialik (who has a doctorate in neuroscience but has come out in favor of alternative medicine and against vaccination) makes all of the common arguments: Tons of non-human mammals eat their placentas immediately after giving birth, so it must be a healthy step that humans have learned to ignore.

"Of all the studies available, only one showed potential for benefit," Clark said. "and it showed the potential for pain reduction immediately after labor. But that particular study, although quite rigorous and convincing, suggested that the placenta had to be eaten right after birth, completely, in its entirety, and that it couldn't be stored or heated," she said. "That's not what human women are doing."

Indeed, most celebs in the news for consuming their placentas aren't praising the benefits of scarfing down a raw organ in the delivery room. Most eat it over time -- sometimes even months postpartum -- after having it dehydrated or cooked, often by a midwife.

"The animal practice that we see simply isn't what humans are doing," Clark said. "So you really can't compare the two."

And as it happens, most of the evidence cited in support of placental consumption is based on studies showing benefits in animals, not humans. Across all available studies, Clark said, only one worked with humans.

This single study is often cited by supporters of the practice as proof that placental consumption increases milk output. The study does conclude this, but it did so without having a control group — women who believed they were consuming placenta but weren't — so there could have been a strong placebo effect. Indeed, a survey of women who'd consumed their placentas found high levels of satisfaction, so the question isn't whether or not women feel good after taking the capsules — it's whether the contents of the capsules are really to thank.

Clark found other methodological holes in the milk production study, now over 60 years old, as well. And in those 60 some years, its results have never been reproduced.

The other studies Clark found all worked with animals, and after combing through them she says their findings don't convincingly translate to human use.

Clark hopes that more rigorous research will come soon, allowing women to make decisions informed by evidence instead of tabloid buzz. But she's more concerned about the lack of data on the potential risks of placentophagy. Most women seek the help of a midwife or doula in preparing the organ, Clark said, and there's no regulation — or even data — on how to do that safely. The idea of a woman eating a fresh, raw organ troubles the study authors even more

"There are no regulations as to how the placenta is stored and prepared, and the dosing is inconsistent," lead author and psychologist Cynthia Coyle said in a statement. "Women really don't know what they are ingesting."

Ironically, many of these women are otherwise incredibly careful about what they put into their bodies. But because they believe eating the placenta is "natural," they're quite unskeptical about the practice.

We now know that placentas actually contain a whole host of bacteria — which is a good thing for baby's developing microbiome, but should perhaps give women pause when considering a raw organ meal. And since it's the placenta's job to protect a baby in the womb, it's possible for it to contain dangerous heavy metals like lead and mercury.

Clark and her colleagues are working on further research to see how widespread the practice has become and how patients and doctors feel about it. They understand their work won't stop many new mothers from wanting to take placenta capsules, so they hope that the research can catch up to the growing trend.

"I hope there’ll be more evidence based research," Clark said. "If this continues to be a practice for women, I'd hope that we could start to say what might actually be beneficial about it, and what might be harmful."

This post was originally published in June 2015. It has been updated. 

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