"Butt Breathing" is back. Could help people who can’t get oxygen the regular way

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Takanori Takebe is on a mission to find out if people can breathe through their butts.

As a medical doctor and stem cell biologist, Takebe spends most of his time trying to develop lab-made livers to treat organ failure. His side quest to explore backside breathing began several years ago, when his father caught pneumonia and had to be put on a ventilator.

“I was really shocked by how invasive it is,” says Takebe, of Cincinnati Children’s Hospital Medical Center in Ohio and the University of Osaka in Japan. Takebe worried about how the procedure might affect his dad — who’d already had part of one lung removed due to a past infection — and his father’s lack of other options if the ventilator wasn’t enough. That got Takebe curious whether there was any way to help patients get oxygen into the body without involving the lungs.

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With his background in gastroenterology, Takebe knew that the human intestinal tract is rich in blood vessels. That’s why enemas can deliver medicine to the bloodstream. Takebe suspected that perhaps oxygen could pass from the intestines into the bloodstream, too.

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Takebe and his colleagues developed an enemalike treatment that sends a liquid called perfluorodecalin up the rectum. This liquid, which is already used in some medical procedures, can be loaded up with oxygen. As it releases that oxygen into the body, space in the liquid’s chemical structure opens to absorb “exhaled” carbon dioxide.

In experiments with mice and pigs, enemas of this super oxygen-rich liquid helped the animals survive low-oxygen conditions. Each 400-milliliter dose boosted pigs’ blood oxygen levels for about 19 minutes at a time. Takebe’s team shared those findings in Med in 2021. Further pig tests reported in 2023 showed the technique could improve animals’ oxygen levels for up to half an hour.

During these experiments, Takebe vividly remembers seeing samples of the pigs’ blood change from a muddy, low-oxygen hue to a brighter, oxygen-rich red. “That was my aha moment,” he says — an indication that this wild idea might actually work.

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Now, the researchers have tested the safety of butt breathing in people. Twenty-seven healthy male volunteers in Japan each took a dose of non-oxygenated perfluorodecalin up the anus and were asked to hold it for an hour. Those smallest dose group got a squirt of 25 milliliters. The biggest dose was a whopping 1.5 liters — the maximum approved for “contrast agent” liquids used in X-ray scans of the GI tract.

Four of the six men in the planned 1.5-liter group had to stop receiving liquid early due to stomach pain. But most of those who got up to 1 liter fared pretty well, bloating and mild tummy discomfort aside, Takebe’s team reports in the Dec. 12 Med. The research was funded by EVA Therapeutics, a start-up that Takebe cofounded to pursue the project.

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