Can You Eat Your Own Poop?

Hello, it is time for "Hey, Science," our nauseatingly scientific weekly feature in which we have your most provocative scientific questions answered by real live scientists (or related experts). No question is too smart for us to tackle, which will be our downfall. This week, medical experts answer the question: Can you eat your own poop?

THE QUESTION: This week's query comes from Gawker writer Max Read (not a joke, I want it to be perfectly clear that this question came from Max Read): Can you eat your own poop? We've all heard of people who claim that drinking your own urine has health benefits (vitamins, etc). Why not poop? Would there by any benefits to eating your own poop? Since it's already been fully processed by our own bodies, how could there be any dangers? Might it even be GOOD for us?

A big difference between urine and poop is that urine is sterile while poop is, well, you know, smelly and full of bacteria.

That said, those are the same bacteria that live in your gut and play many healthy roles in your body, so coprophagy [Ed.: this means "eating poop," write it down] is not necessarily unhealthy unless the poop originates from an unhealthy individual.

In fact, a recent article published in the prestigious New England Journal of Medicine showed that fecal transplants, where poop from one individual is infused into another individual's intestines, have performed better than regular antibiotics in treating certain bacterial infections that cause severe diarrhea.

Parul Agarwal MD, assistant professor of Gastroenterology & Hepatology, University of Wisconsin:

Thank you for this interesting inquiry. Drinking your own urine and eating your own poop is perfectly safe. Urine is sterile, poop is not, but they are your own bugs. There are no positive effects of eating your own poop that I know of. Hope this helps. [Ed.: it does help Max Read, in particular.]

Lars Eckmann, PhD, professor of medicine at UCSD Medical School, Division of Gastroenterology:

Interesting question. In theory, ingesting your own stool should not be harmful, as long as it "clean" (i.e., not contaminated with stool from others, as might occur by contact in a toilet bowl, etc). Furthermore, there may be a theoretical minor health benefit in doing so. Bacteria in the colon can metabolize non-absorbed food materials (fiber) and generate useful nutrients (e.g. vitamins such as biotin, or sugars and amino acids from fiber and other undigested materials) that are only partly absorbed during initial production, the rest is excreted with the stool. Re-uptake of these nutrients by ingestion of stool would give a second opportunity for absorption in the gut. In fact, coprophagy in mice (a normal behavior) helps to extract extra energy from food compared to mice that are prevented from coprophagy.

However, any theoretical biological benefit is heavily outweighed by our strong aversion to coprophagy. The primary reason for that is probably the unconscious awareness that stool is often a source of infections in humans (because we do not get to ingest "clean" stool, but rather mixed stool from other people). Practically all food-borne infections are ultimately transmitted through the stool (fecal-oral), so we have very good reasons to stay away from stool as much as possible by hygienic measures (toilet construction, separate drinking and waste water systems, etc).

Having said that, an increasing medical interest exists in "stool transplantation", where normal, "healthy" stool gets ingested by patients who suffer from certain forms of diarrheal disease caused by use of antibiotics. The challenge is to standardize the stool preparations and formulate them in ways that are acceptable to patients.

P.K. Newby, ScD, MPH, MS nutrition scientist and food writer:

Bottom line: the human body is a wondrous machine, with complex systems designed to extract nutrients from food and, during metabolism, excrete the waste products in the form of both liquids (urine) and solids (feces). The body is not 100% efficient, however (no machine is), so there could be some residual nutrition left in the waste.

That said, whatever small amount of nutrition that remains, which can have utility in some cases—-a likely explanation why certain species do eat their poop, like dogs; why poop from some species provides nutrients for others; etc—-it's not a terribly efficient way of obtaining energy and nutrition for humans. Your body has excreted this waste, and reconsuming it is literally a waste of energy and, further, could be harmful; there's a reason your body is excreting this waste, after all, and no reason to further tax your excretory and digestive systems with remetabolizing it.

There is likely some innate biological proclivities at play here that would lead a human to want to consume his/her waste, likely going back to days of hunting and gathering when food was scarce. But that is no longer the case in many places (like the US setting), thus there are certainly healthier, safer, and tastier ways of obtaining nutrition for our bodies in the 21st century.

In summary,consuming foods naturally rich in vitamins, minerals, and other things the body needs, like vegetables, fruits, whole grains, nuts and seeds, for example, are a better way to go than, say, consuming the waste of those (or whatever) foods.

THE VERDICT: Assuming you are a healthy person, eating your own poop would probably not harm you. Eating someone else's poop could make you sick if they were unhealthy, but eating poop from the right person could cure your diarrheal disease. But generally speaking, Max Read should stick to eating real food.

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