Blend it in your smoothie, cook it in lasagna or even dehydrate it and pop it into pills… how do you like your placenta served?

An increasingly popular “superfood” that promises to protect against postpartum depression, it seems like people just can’t get enough of placenta lately.

Kourtney Kardashian is a big fan, January Jones has said it gave her “so much energy” and Alicia Silverstone was “really sad” when her placenta pills were finished.

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But a new study has found that not only does eating the placenta (or “placentophagy”) offer no proven, science-backed health benefits, it could also be dangerous. (Post continues after gallery.)

Published in Archives of Women’s Mental Health, the Northwestern Medicine reviewed 10 current published research studies on placentophagy and found no human or animal data to support any of the purported health benefits.

These included no supporting evidence to the claims of boosting energy, help with lactation, promoting skin elasticity, replenishing iron in the body, enhancing maternal bonding or protecting against postpartum depression or post-delivery pain.

Worryingly, researchers found no studies that examined the risk of eating the placenta.

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“Bacteria and elements such as mercury and lead have been identified in the post-term placenta,” corresponding study author Dr. Crystal Clark told CBS News.

“So if the theory is that we retain nutrients and hormones such as oestrogen and iron that could be beneficial, then the question becomes what harmful substances can also be retained that could harm the mother or the baby if she is breastfeeding,” she said.

"There are a lot of subjective reports from women who have perceived benefits, but there hasn't been any systematic research investigating the benefits or the risk of placenta ingestion," says Dr Clark.

"The studies on mice aren't translatable into human benefits," she says.

Lead author Cynthia Coyle says its worrying that so little is known about the risks.

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"Our sense is that women choosing placentophagy, who may otherwise be very careful about what they are putting into their bodies during pregnancy and nursing, are willing to ingest something without evidence of its benefits and, more importantly, of its potential risks to themselves and their nursing infants," she says.

"There are no regulations as to how the placenta is stored and prepared, and the dosing is inconsistent. Women don't really know what they are ingesting."

The study reports that although almost all non-human placental mammals ingest their placenta after giving birth, the first documented accounts of postpartum women eating placenta were in the 1970s, but has gained significant popularity in recent years.

"Our sense is that people aren't making this decision based on science of talking with physicians. Some women are making this based on media reports, blogs and websites," says Dr Clark. (Post continues after gallery.)

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