By Tracy G. Cassels

The act of eating one’s placenta after birth, placentophagia, seems to be becoming more popular than in previous years.  Though many women cite hormonal or emotional benefits to ingesting the placenta, very few are aware of the science looking at this practice.  Who does this?  Why?  And does science support the practice?

Placentophagia in Other Animals

What most women refer to when deciding to engage in placentophagia is that almost all placental animals do it

[1].  And as we know, evolution works that such an act would either have a benefit to these mothers or, at the very least, cause no harm.  Mark Krystal from the University of Buffalo has spent nearly 40 years studying placentophagia in animals.  Specifically, he has spent this time studying six different hypotheses as to why animals engage in this practice:

  1. It keeps the nest area clean;
  2. It reduces odours that would attract predators;
  3. It replenishes nutritional loss from pregnancy;
  4. It allows mom to acquire needed hormones;
  5. It is simply a response to hunger after birth;
  6. It expresses a tendency towards carnivorousness post-birth.[1][2]

All of these are possible causes of placentophagia in animals, and depending on the research, it may mean it is relevant or not for humans.  In a review of the research examining these six hypotheses, Krystal and colleagues immediately dismiss numbers 5 and 6 due to the evidence of animal behaviour that would contradict this[3].  However, of the remaining, none explained the behaviour for all groups of animals who partake in this, suggesting that there are multiple reasons animals eat the placenta.  For example, if an animal eats the placenta for the nutritional value, it also serves to reduce odours that might attract predators, even if that reduction is not the actual cause of the behaviour.  As such, it seems that the first four hypotheses may be seen as possible causes for groups of animals, even though not all will apply to each animal.


Importantly, though, they mention some of the effect that may reinforce the behaviour as beneficial to animals.  That is, although these are secondary consequences, they are benefits that also reinforce the act of placentophagia:

  1. The act increases attraction to and caring for the neonate.  The attraction of the placenta and amniotic fluids means the mother interacts with her baby sooner than a cleaned neonate[4] which elicits maternal caretaking behaviour[5].
  2. The act results in a neurochemical increase of the pain threshold.  The ingestion of the placenta both increases opioid production[6] and enhances morphine-mediated pain relief[7].  Importantly, this effect actually raises pain relief without interfering with maternal caretaking behaviour, which would be disrupted if the pain relief source was not from the placenta but from a drug[8].
  3. The act increases neurochemical maternal behaviours.  The opioid activity mentioned above also serves to increase activity in the “maternal neural substrate” (the area of the brain associated with caregiving and maternal behaviours), even in nonpregnant animals[9].

Given the benefits in terms of causes and consequences, it shouldn’t be surprising to see humans attempt to gain these benefits.  But do we?

Placentophagia in Humans

placentaLet us first be clear: Placentophagia is an exception in human cultures despite being a norm in mammals.  There is no evidence that this practice was ever widespread or is routinely practices in any culture, including small hunter-gatherer tribes, remote cultures, etc.[1][10].  In fact, the modern emergence of placentophagia seems to be the most widespread practice uncovered for humans, though it has appeared in the past in Chinese medicine (though not as widespread as some seem to believe) and some smaller cultures.  So why do people do it?  Research seems to suggest three main reasons:

1.  People believe there are general health benefits;

2.  People believe there are specific health benefits;

3.  The idea that it is “natural” given that animals do it and we are animals.[3]

Does evidence support any of these reasons as being reasons why people should engage in placentophagia?  It’s hard to say because there is so very little well-done research on it.  Though there are studies that purport things like benefits to breastfeeding[11] (and for a review, see [1]), the studies are not of a quality that allows for conclusions to be made.  Research on animals has found health benefits, though (as mentioned above) though there are caveats to that as well.  For example, the beneficial effects of the opioids wane if the placenta is left at room temperature for 24 hours, but if frozen immediately, the effects are preserved[3].  Again, though, these may not apply to human placentas and we don’t even quite know where to begin to measure the effects of placentophagia as we have no idea what part of the placenta might be helpful, when does it have to be ingested, does the placenta need to be frozen, and so on.  And perhaps most importantly, because there is no history of placentophagia in humans, we also have no baseline to compare it to.

The question we must be asking now is, “Why isn’t placentophagia common in humans?”  After all, if we accept that we evolved from mammals, why did the practice disappear?  (And if you don’t accept we evolved from mammals, perhaps it’s still an interesting question, but not as evolutionarily pressing.)  One possibility is culture[3].  One of the main reasons for placentophagia in animals is pain reduction via the increase in opioids, but what if the lack of pain reduction is what allowed other individuals, mainly women, to help the labouring mother before and after, strengthening social bonds between the community members.  This would also result in the transmission of information about birth between women.  And of course a second issue may be the view that placentophagia is a form of cannibalism, which was reported in a cross-cultural survey on the practice[10].  Furthermore, as humans became bipedal, we know that birth became safer when assisted versus unassisted (and remember this is historical assisted which means the inclusion of any other person there, not a medical professional)[12], any aspect of the birth that increased the likelihood of help would further serve the species, and increased pain would be one thing that would summon others.

As a slight aside, this raises an interesting question about why we are seeing a rise in placentophagia in modern, Western worlds: We are lacking the usual support that historically women had post-birth, might this be the reason women are turning to something that may offer pain relief and general health benefits, particularly for post-partum depression (a condition we know is linked to a reduction in support[13])?  Is this reduction in a village to support families driving the rise in animalistic practices in hopes they will have the same effect for us humans?  What does it mean for us as a species?  Just some thoughts to consider.


Well, we know that placentophagia is not common in humans, but rather a relatively new phenomenon in terms of any widespread use.  We have no idea if there are health benefits outside of the anecdotes of those who partake in it.  So far there does not seem to be reason to believe it is dangerous, but that is a possibility for why it is not common in humans[3] (though our understanding of culture would suggest it would be widespread knowledge if, in fact, it posed a danger).  Should you do it?  It’s a personal decision.  There is nothing suggesting you will be lacking if you don’t or receiving benefits if you do.  Although potentially, the cultural possibility for cessation of this act may suggest that people do receive some benefits if they are not in a caring, supportive community, especially with the increased rates of post-partum depression we see today.  But that’s pure speculation by yours truly and requires more research.  At the end of the day, whatever makes you happy.

Did you ingest your placenta?  Did you find it helped your or did you find no effect?

 [Image Credit: One Bode]

[1] Kristal MB.  Placentophagia: a biobehavioral enigma.  Neuroscience and Biobehavioral Reviews 1980; 4:141-50.

[2] Lehrman DS.  Hormonal regulation of parental behavior in birds and infrahuman mammals.  In Sex and internal secretions, vol 2, ed WC Young, 1268-1382.  Baltimore: Williams and Wilkins, 1961.

[3] Kristal MB, DiPirro JM, Thompson AC.  Placentophagia in humans and nonhuman mammals: causes and consequences.  Ecology of Food and Nutrition 2012; 51: 177-97.

[4] Kristal MB, Whitney JF, Peters LC.  Placenta on pups’ skin accelerates onset of maternal behavior in nonpregnant rats.  Animal Behavior 1981; 29: 81-5.

[5] Kristal MB.  The biopsychology of maternal behavior in nonhuman mammals.  ILAR Journal 2009; 50: 51-63.

[6] Kristal MB, Thompson AB, Grishkat HL.  Placenta ingestion enhances opiate analgesia in rats.  Physiology & Behavior 1985; 35: 481-6.

[7] Kristal MB, Thompson AB, Abbott P.  Ingestion of amniotic fluid enhances opiate analgesia in rats.  Physiology & Behavior 1986; 38: 809-15.

[8] Rubin BS, Bridges RS.  Disruption of ongoing maternal responsiveness in rats by central administration of morphine sulfate.  Brain Research 1984; 307: 91-7.

[9] Thompson AC, Kristal MB.  Opioid stimulation in the ventral tegmental area facilitates the onset of maternal behavior in rats.  Brain Research 1996; 743: 184-201.

[10] Young SM, Benyshek DC.  In search of human placentophagy: a cross-cultural survey of human placenta consumption, disposal practices, and cultural beliefs.  Ecology of Food and Nutrition 2010; 49: 467-84.

[11] Soykova-Pachnerova E, Brutar V, Golova B, Zvolska E.  Placenta as a lactogogon.  Gynaecologia 1954; 138: 617-27.

[12] Rosenberg K, Trevathan W.  Birth, obstetrics and human evolution.  British Journal of Obstetrics and Gynecology 2002; 109: 1199-206.

[13] Hagen EH.  The functions of postpartum depression.  Evolution and Human Behavior 1999; 20: 325-59.