The thought of transplanting another person’s feces into your colon may sound uncomfortable, and understandably so. Feces are a foul-smelling mixture of water, undigested food, dead and living bacteria, and other cells and substances. However, live bacteria in feces have proven their value in the treatment of diseases and ailments of the digestive tract. That’s why for years doctors have transferred feces from healthy donors to sick patients—usually by colonoscopy, enema, or pills—to restore gut health.
The concept is relatively simple: the good bacteria from the donated feces will colonize the patient’s gut if the recipient’s microbiome is out of balance and outcompete any problem-causing bacteria. For example, healthy fecal bacteria can be used to treat an infection Clostridioides difficile bacteria, which can infect the human colon and cause mild to life-threatening diarrhea. In clinical trials, fecal microbiota transplants are estimated to be more than 90 percent effective in clearing C. diff infections. And just last month, researchers from Norway wrote in the journal Gastroenterology that patients with irritable bowel syndrome (IBS) suffer less from bloating, stomach cramps and constipation after fecal transplant treatment – even three years after receiving it.
David Ong, a gastroenterologist at Mount Elizabeth Hospital in Singapore, sees even greater potential for these treatments as gut microbes interact with our brains and other organs. Ong, who in 2014 was the first doctor in Singapore to perform a fecal transplant on a patient infected with C. diff, says recent studies suggest the intervention could also help people with inflammatory bowel disease or obesity, or those on the autism spectrum with guts problems related to picky eating. There are currently more than 100 clinical trials investigating the effect of fecal transplants on conditions ranging from depression to epilepsy and Covid-19 to cancer.
“Genes are what you’re born with, and that’s what they are,” says Ong. “But the gut microbiome is something you can manipulate. And if you can manipulate that to a good outcome in terms of disease, that’s great.”
But there’s just the small matter of finding the right poo. In addition to working as a gastroenterologist, Ong co-founded the startup Amili, which currently houses the only fecal transplant bank in Southeast Asia. She has collected more than 1,000 stool samples over the past three years. However, most willing donors were excluded after completing a questionnaire and having their stool, blood and saliva tested in a laboratory.
Lifestyle, diet, medical history – including the use of antibiotics, which can kill gut bacteria – and the way someone was born can rule people out. (Infants born vaginally pick up their first gut bacteria from their mothers as they move through the vaginal canal and show greater microbial diversity than those born by caesarean section.) In the Norwegian trial, stool samples used to treat 87 patients with IBS came from one donor: a 36-year-old man who was born vaginally; breastfed; was a non-smoker; treated with antibiotics only a few times; exercise regularly; and consume large amounts of protein, fiber, minerals and vitamins. Generally, when a donor is deemed healthy enough, lab technicians will examine their stool sample. Technicians look for different microbiomes, especially bacteria known to compete with harmful bacteria.
