Earlier this week, a friend forwarded a New York Times article to me, asking if I'd read it yet. It was an interesting read that focused on the microbiome of the placenta and whether or not it plays a role in the development of an infant's gut bacteria. I was almost inspired into writing up a blog post, but I got sidetracked, as usual.

A few days later, Sabine Wilms posted some thoughts about the placenta on a Facebook page.  She wanted "to clarify the use of human placenta in the context of postpartum recovery in classical Chinese medicine." She pointed out that placenta is not mentioned in the Jingui Yaolue (Han Dynasty, 25-220AD) nor the Beiji Qianjin Yaofang (Tang Dynasty, 618-907AD.) This got me to thinking about the many health care providers and mothers I know who recommend the practice.

I have heard and read many times that "maternal placentophagy" (whereby the placenta is eaten by the mother who birthed it) is a practice dating back thousands of years in China. These types of claims are repeated over, and over, and over and over, across the internet. In lesser cases, people or organizations claim that general placentophagy (which just means that the placenta was eaten by somebody, at some point, after the mother birthed it) has been going on for hundreds or thousands of years, implying that there was an ancient practice in which human mothers ate their placentas. With the veritable void of research on the topic, it seems easy enough for misinformation to spread across the human sphere like wildfire.

On the advice of my natural health care provider, I had my placenta encapsulated with my second son in 2012. I actually experienced negative effects while taking it, that included muscle fatigue, a minor tremor and mood swings. Taking it may have contributed to problems with my milk supply. In the time since, I've heard and read similar stories from other women, though of course, this is all anecdotal (and individuals respond differently to medicinals -which is why we individualize our treatments in EAM, right?) Even so, these types of experiences have prompted me to wonder:  In a mess of unreliable information combined with a lack of research around maternal placentophagy, how do we know how to best advise our patients on this matter?

Maternal placentophagy does not seem to be found in any of the Classical texts of East Asian medicine (that we have found so far). We have no record of it's use in the Shennong Bencao (~200 BC), Zhang Zhongjing's Jingui Yaolue (~200 AD) or Sun Simiao's Beiji Qian Jin Yao Fang (7th Century). Li Shizhen lists it in the Bencao Gangmu (1578) in his chapter on Renbu, but it appears to be used as a medicine, whereby it was thoroughly cleaned of blood, dried in the sun, pulverized and mixed with herbs (except in the case of an eye wash) and then served to somebody other than the mother.

I find no mention whatsoever about the use of placenta, postpartum or otherwise, in Fu Qingzhu's Gynecology text (17th/18th Century). It is mentioned in Miao Xiyong's Shennong Bencao Jingshu (1625and said to be "a medicinal that tonifies dual deficiency of yin and yang, with the ability to restore the root and return the primal [qi]" (Bensky, Clavey, Stoger). Zhang Luzhuan mentions it in the Benjing Fengyuan (1670) and Zhao Xuemin tells us in the Bencao Gangmu Shiyi (1800) that it treats emaciation and facial pigmentation. Again, none of these authors appears to mention a woman eating her own placenta. Instead, it is treated as a medicine that is used to treat disorders of people other than the mother. It is possible that a postpartum mother might be the recipient of one of these medicinals, but the point is that placenta is not a general tonic that is given to all postpartum women after birth. It seems that it is never mentioned as a substance for postpartum tonification in the Classical Chinese literature.

Mark Kristal has been studying maternal placentophagy since the 1970's. I am not very excited about the ethics in his research, since it involves torturing a vast number of animals. (I believe we can use more creative methods that define our human character in a more positive way.)  However, due to the lack of research in the field, I am including some of the more important points he has made here.

Kristal showedwith rats, that there is a biological mechanism behind their consumption of both amniotic fluid and the placenta. When rats lick their amniotic fluid during birth, they get a dose of something his team termed Placental Opioid-Enhancing Factor (POEF). The POEF works as an analgesic, reducing the pain that the animal is experiencing during labor. In addition to this, his team noticed that the consumption of amniotic fluid and placenta by the mother helped to initiate the mothering instinct towards the newborns. This idea can be used with rats who have never been pregnant, to help them initiate mothering behaviors (to adoptee rats) sooner than they normally would. The mechanisms of all of this are quite interesting and you can read more about them in the article, Placentophagia in Humans and Non-Human Mammals: Causes and Consequences. At the end of the article, Kristal tells us:

The complementary question to “Why do mammals eat placenta at parturition?” is “Why don’t humans eat placenta at parturition?” Strictly speaking, if placentophagia is not a biologically determined behavior in humans, we should assume that there must be a good adaptive reason for its elimination.

Wait, but haven't humans been eating their placentas for hundreds, if not thousands of years (in China) like all these people are saying? The answer is a big fat NO, according to Sharon Young and Daniel Benyshek. In 2010, they searched the Human Relations Area Files database that has been kept at Yale University since 1949. The purpose of the database is to contribute to an understanding of world cultures by offering a forum for the collection of cultural, behavioral and background information on peoples across the world. At the time that Young and Benyshek did their search, they looked at the 179 cultures currently in the database for any mentions of maternal placentophagy. Here's what they foundOnly ONE record in the entire search mentioned the practice of maternal placentophagy.

"One Anglo mother, known by two midwives, was reported to have roasted the placenta and supposedly received a surge of energy after its consumption." Given that the description of maternal placentophagy refers to an “Anglo” mother in the U.S.-Mexico borderland, and, due to the lack of additional corroborating accounts regarding the practice in the larger Chicano literature, the description may be a reference to the recent practice of placentophagy as advocated by some midwives in Mexico and the U.S. first noted in the 1970s, rather than a longstanding Chicano tradition.

Of course, Kristal pointed out William Cowper's observation that "Absence of proof is not proof of absence." Yet, why is it that the routine practice of fringe activities that go against major taboos (like cannabalism) can be found in the database without any other mention of maternal placentophagy? If some human culture on Earth had practiced it, would it not be easier to find than routinely practiced cannabalism? According to the search, what do humans do with their placentas? They bury it (55%), put it in a specific location (14.8%), incinerate it (9.4%), hang it in a tree (8.3%), discard it to be eaten by animals (7.7%), use it as medicine to be given to somebody other than the mother later (1.8%) or wrap, hang or or symbolize it in some other, unique manner (3%). Of the 4000 known land mammals, every species practices maternal placentophagy except for camelids and humans.

Although the placenta is known to be readily and eagerly ingested by nearly all other mammalian mothers, including our closest primate relatives, few, if any known human cultures appear to promote or allow its consumption, even in a ritualized context. We suggest that, in the face of many detailed ethnographic descriptions of cultural beliefs and practices regarding the placenta, including its proper treatment/disposal, the lack of a single unambiguous account of a well documented cultural tradition of maternal placentophagy is good evidence that it is absent (or at most, extremely rare) as a customary or learned practice in human societies cross-culturally, and that its postpartum consumption by the mother may even constitute something akin to a universal cultural avoidance.

Taboos against placentophagy seem to be more universal than taboos against cannibalism. Why would human beings have such a homogenous cultural avoidance to this behavior? Kristal put forward a possible theory in his article. It's based on Desmond Morris's theories in The Naked Ape. Morris argues that non-procreative sex in human beings happens to satisfy social bonds - those bonds being a large piece of why humans have known such success on the planet. Kristal postulates that perhaps by not utilizing the analgesic effects of the placenta through consumption, a mother makes herself more reliant on her social group for assistance during the birth, which has the additional benefit of helping to ensure the successful birth of an infant with a large head size (in comparison to other mammals.)

This theory is interesting, but in my (anthropologically uneducated) opinion, it's a big stretch. At this point, until we have more research into why human mothers have traditionally avoided eating their placentas, it can all be one whack theory after another. But, in a 2012 article, Young, Benyshek and Lienard put forward a pretty amazing supposition. I imagine that it took a few beers for them to come up with their idea, and it is also a pretty big stretch, but it's a more believable stretch, at least for me. More importantly, their idea brings with it some pretty strong potential health implications that health care providers need to consider.

THE FIRE HYPOTHESIS

(I am still lost in the awesomeness of this idea and imagining the three authors camping out next to a river somewhere. One of them is cooking a hot dog on a stick and the smoke keeps following her as she tries to find a nice place to breathe. And viola! The solution to why human women do not eat their placentas! Ha!)

The absence of human placentophagy, the maternal consumption of the afterbirth, is puzzling given its ubiquity and probable adaptive value in other mammals. We propose that human fire use may have led to placentophagy avoidance in our species. In our environment of evolutionary adaptedness, gravid women would likely have been regularly exposed to smoke and ash, which is known to contain harmful substances. Because the placenta filters some toxicants which then accumulate there across pregnancy, maternal placentophagy may have had deleterious consequences for the overall fitness of mother, offspring, or both, leading to its elimination from our species' behavioral repertoire.

While cooking with fire substantially increases the availability of energy and can eliminate many pathogens and toxins found in raw foods, open fires also increase exposure to specific environmental metals and other toxic substances through smoke inhalation.

If I go back to my college bio classes, I remember all those cool bits about natural selection and this theory starts to make some serious sense. It's simple, right? If we participate in a behavior that impairs our ability to reproduce (or more importantly, to live), that behavior will be eliminated through a die-off of those who practice it.

The placenta acts as a filter between mother and child and there are a few heavy metals that scientists know it tends to filter out completely. This means that it becomes a sponge for some types of toxicity. And, as we know, toxicity can affect the reproductive organs.

Unlike many other metals, cadmium, inorganic mercury, and trivalent chromium are trapped by the placental barrier in pregnant mothers and accumulate across pregnancy.

Due to natural processes in the prehistoric world, heavy metals were released and uptaken by plants that humans then burned for warmth and cooking. The authors surmise, from modern day scenarios, that women were particularly vulnerable to smoke inhalation and thus, incurred a build-up of heavy metals in their bodies. Cadmium buildup, in particular, can affect the reproductive fitness of an individual. The Fire Hypothesis paper lists several research studies showing cadmium to have a negative impact on the production and function of reproductive hormones. It also acts as an endocrine disruptor. Smokers tend to have high levels of cadmium buildup in their placentas and the authors have used smokers as a modern day analogue for their study.

Since cadmium has a long half-life of about 20 years, multiple births in which the placenta is eaten, in addition to accumulation from chronic smoke exposure, would cause increasingly higher accumulations of the metal before the mother’s body would have been able to excrete significant amounts of the toxicant.

Under such circumstances, consuming this now heavy-metal-laden organ could then have caused damage to the mother’s health, and the health of her offspring through breastfeeding, since breast milk contains approximately 10% of maternal blood levels of cadmium, and eventually threaten the long-term reproductive fitness of mother, offspring, or both.

Regardless of whether The Fire Hypothesis is true, it points us to some problems around the consumption of human flesh, especially when we are talking about an organ that acts as a filter. We live in a world where even healthy people cook in teflon coated pans, use new PVC piping for our water transfer, have lead paint chipping off into our outdoor soils, drink from bleached paper coffee mugs, eat foods stored in BPA coated cans and go inside buildings that are off gassing chemicals. While we may not cook over wood fires anymore, we do live in close proximity to roads and freeways, where we are subject to the pollution spewing out of automobiles. And from over us, jet fuel rains down into our water and soil.

Harvard published a study in 2011 that measured 87 environmental chemicals in 2000 pregnant women in the Faroe Islands (Denmark). Almost all of the chemicals were found in both maternal and fetal tissues. The same year, UCSF looked at almost 300 American women, and found BPA, lead, cadmium, flame retardants, rocket fuel  (perchlorate) and other chemicals in their tissues. We still don't understand the full role of the placenta, nor all the constituents that it includes. What is highly likely is that human beings have avoided maternal placentophagy for a good reason. In the modern day, it's more important than ever that we look at the toxicity in the foods we are eating. In addition to our toxic exposure, we are at the top of the food chain, eating animals who have concentrated any chemicals that plants are up taking.

Is it really in the best interest of mother and child for a woman to consume human flesh, in particular, a filtering organ, while she is attempting to recover from pregnancy and breastfeed a child? Based on the information that I was able to find, combined with the number of food, lifestyle and medicinal tools that we have at our disposal, I really can't justify recommending the practice. As we begin to understand more about the role of the placenta and why humans have avoided it (until the 1970's in America), I may change my opinion.

How can we address postpartum tonification through food, diet and lifestyle?  I investigated the topic more in the week following this post and you can find those additional thoughts here.