As Zain Kassam, the chief medical officer at OpenBiome, told me in an email conversation, a lot of testing has gone into ensuring that these stool samples have been optimized to contain just the right types of microbes. “Safety is OpenBiome’s number one priority,” he told me. “In fact, only 2.8 percent of candidate stool donors pass our robust safety protocols. Having graduated from Harvard, I can say it’s harder to be admitted to OpenBiome as a poop donor than to get into Harvard.”

But will the poop capsules really work when it comes to curing obesity?

The lead researcher conducting the clinical trial, Elaine W. Yu, an assistant professor at Harvard Medical School and a clinical researcher at Massachusetts General Hospital, told me that there has been encouraging scientific evidence that intestinal microbes might actually play a role in treating obesity.