The idea of having a fecal transplant sounds like the ultimate sign of a culture obsessed with wellness.

But unlike so many discredited or ineffective alternative medicine concepts, fecal transplantation actually works. It's a well-studied method approved by the FDA for fighting one of the deadliest superbugs in the world, and is currently being studied as a potential therapy for a wide range of other illnesses.

It's technically known as "FMT" for fecal microbiota transplantation, but is also called a microbiome transplant, a poop transplant, or even poop pills. It involves taking stools from a healthy donor, straining them in a saline solution, and implanting them in the colon of the recipient. It can be done a variety of ways, including surgically, through an enema, or by swallowing a capsule of freeze-dried material.

As the advocacy group the Fecal Transplant Foundation writes, the scientific basis behind FMT is that a stool from a healthy donor can "replace good bacteria that has been killed or suppressed, usually by the use of antibiotics, causing bad bacteria ... to over-populate the colon." Basically, the healthy bacteria takes over for the dead bacteria, and quickly begins replicating itself.

And done as a treatment for the superbug Clostridium difficile infection (CDI), FBT has a success rate of as high as 90 percent. CDI is an infection of the large intestine (also called the colon) that occurs as a reaction in about 3 percent of people who take heavy doses of antibiotics. Many CDI cases are extremely mild, and resolve themselves by just stopping taking the antibiotics. But in more severe cases, the colon can be severely damaged, leading to infection or death.

Easily spread and extremely infectious, CDI can cause diarrhea, fever, dehydration, and extreme abdominal pain. The rise of drug-resistant bacteria has fueled a major increase in CDI, and it's estimated by the New England Journal of Medicine that just in 2011, at least 500,000 people were sickened with CDI; with 29,000 deaths occurring.

FMT has become a standard therapy for these severe cases, showing a high success rate and few side effects. Many patients see their CDI permanently cured with just one transplant, when many rounds of antibiotics have done nothing, and possibly made the problem worse. The first randomized clinical trial comparing FMT to antibiotics as a treatment for CDI was so successful that it was ended early, and all participants given transplants.

Fecal transplantation to cure microbial illness has been around since at least the 4th century CE, when Chinese texts mention it as a treatment for food poisoning. But a number of issues have kept it on the fringe. One is the "ick factor" of having someone else's poop transplanted into you. But a far more serious barrier to widespread FMT use is its status with the FDA.

Because the FDA classifies human stool as a biological agent, it's seen as an investigational new drug (IND), and subject to a complex set of standards, including the need for approval every time a doctor wants to use it, as well as signed consent forms.

The FDA was lax in enforcing these rules until a new set of guidelines came down in 2016, mandating that FMT patients personally know their stool donor, and their doctor must oversee both the production and the transplantation of the material. This has had adverse affects on the few stool banks that provide screened material for transplantation, though hospitals can still produce and transplant material, as long as they follow other FDA regulations.

At this point, the only approved use for GMT is the treatment of CDI. All other uses are banned by the FDA. However, small scale clinical trials are underway to study FMT as a therapy for everything from Chron's disease and IBS to HIV and autism.

While many of these studies are extremely small, with results years away, if they do work, users might find the need for an actual transplantation supplanted by new pills designed to treat a range of illnesses.

But fecal transplantation is a long way from being a first line treatment for anything but severe CDI. As the New Yorker cautioned in a long article about the treatment, "among the desperately ill, FMT’s reputation as a wonder cure has outstripped the science supporting its use." While anecdotal stories claim it's a miracle cure for various illnesses, the few trials that have been carried out have had decidedly mixed results.

To get around FDA regulations and the reluctance of doctors to perform unproven procedures, some people suffering from serious diseases have gone to unlicensed illegal clinics, or given themselves transplants. Some websites even given instructions for a DIY poop infusion. Doctors and clinical journals have, unsurprisingly, recommended against this.

Until more studies are done, FMT likely will remain a treatment only for drug resistant CDI. But for patients suffering from CDI who can get past the inherent difficultly of undergoing a stool transplant, it could be the closest thing medicine has to a miracle cure for this particular illness.