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Takanori Takebe has a very specific and unusual mission. He wants to discover if people can breathe through their backsides. This is not his usual type of research. Takebe is a physician and scientist who spends most of his time growing lab-made livers. He does this to help treat patients with organ failure. However, his side quest to explore backside breathing began several years ago. It started when his own father became very sick with pneumonia.
At the time, Takebe’s dad had to be hooked up to a ventilator. This involved snaking a tube down his throat so that a machine could push air into his lungs. “I was really shocked by how invasive it is,” says Takebe, who works at Cincinnati Children’s Hospital Medical Center in Ohio. He also works at the University of Osaka in Japan.
At the time, Takebe's father had to be connected to a machine called a ventilator. This treatment involved a medical team snaking a tube down his throat. The machine then pushed air directly into his lungs. Takebe was shocked by how invasive the procedure was. He works at the Cincinnati Children's Hospital Medical Center in Ohio. He also works at the University of Osaka in Japan. He worried deeply about how the ventilator might affect his father. Doctors had already removed part of his father's left lung due to a past infection. Takebe was also concerned that his father had no other options. What if the ventilator did not provide enough oxygen? This question made the scientist very curious. He wondered if there was any way to get oxygen into the body without using the lungs at all.
The idea came to him when a student brought a book into his lab. The book described how some animals get oxygen through their skin or their guts. Freshwater fish called loaches are a good example. They can swallow air and absorb oxygen through their intestines. This trick helps them survive in the water. It happens when their gills cannot pull enough oxygen from the water. Takebe is an expert in the branch of medicine that deals with the digestive system. He knew that the human intestinal tract is rich in blood vessels. This is why treatments called enemas work. Enemas send liquid up a patient's bottom to get medicine into the bloodstream. It made Takebe suspect that oxygen could also pass from the intestines into the bloodstream.
Takebe's team devised an enema-like treatment for this goal. It sends a liquid called perfluorodecalin up the rectum. This liquid can be loaded up with lots of oxygen. As it releases that oxygen into the body, space opens up within the liquid's chemical structure. The liquid can then absorb carbon dioxide that is exhaled. The scientists first tested this idea in mice and pigs. The super-oxygen-rich liquid did help the animals survive low-oxygen conditions. Pigs received 400-milliliter doses. That is slightly more liquid than a 12-ounce can of soda. Each dose boosted the pigs' oxygen levels for about 19 minutes. Takebe's team published those findings in 2021. Later tests on pigs showed the technique could improve oxygen levels for up to half an hour.
During these experiments, Takebe vividly recalls seeing samples of the pigs' blood change color. It shifted from a muddy, low-oxygen hue to a bright, oxygen-rich red. That was his "aha" moment. He realized this wild idea might actually work. In 2024, the research won an Ig Nobel Prize. This is a fun award for science that makes people laugh, then think. "Thank you so much for believing in the potential of the anus," Takebe said at the awards ceremony.
Now, Takebe's group has tested the safety of butt breathing in people. Twenty-seven healthy men in Japan volunteered to take a dose of perfluorodecalin up the anus. They were asked to hold it there for an hour. The liquid was not loaded with oxygen as it would be for a real treatment. The scientists just wanted to see if people could hold this liquid in their guts without it harming them.
Volunteers received different amounts of the liquid. The smallest dose was a squirt of 25 milliliters, about 5 teaspoons. The biggest dose was a whopping 1.5 liters, about 1.5 quarts. That is the most amount currently allowed for other medical procedures that send liquid up the bum. Four of the six men in the 1.5-liter group had to stop receiving liquid early. It hurt their stomachs too much. But most of those who got up to 1 liter fared pretty well. Their worst complaints were bloating and mild tummy pain.
Takebe's team shared its findings on December 12, 2025, in the journal Med. The research was funded by EVA Therapeutics, a company Takebe cofounded to pursue butt breathing. The new results hint that this treatment could be safe for people. Still, that does not mean it is effective. Future studies will have to show whether this treatment actually gets oxygen into people's bloodstream.
Doctors and scientists have mixed reactions to this research. One serious skeptic is John Laffey. He is a doctor and scientist who specializes in lung failure. He works at the University of Galway in Ireland. Researchers should focus on improving treatments that support the lungs, Laffey says. They should not be trying to make other body parts do the lungs' job. The lung, even an injured lung, will always exchange gas way better than any other organ. That is what it is designed for. Even if people can get oxygen through the intestines, that would not make it practical. A liter of perfluorodecalin carries 500 milliliters of oxygen. We use 250 milliliters per minute. It is just very hard to see how this would work. At the very least, sustained oxygen support would require a lot of enemas, over and over.
Kevin Gibbs is more intrigued by the treatment. He is a critical-care lung doctor at Wake Forest University School of Medicine in Winston-Salem, North Carolina. "It definitely raised my eyebrows," Gibbs says of the butt-breathing idea. "As someone who treats a lot of people who have low oxygen levels, I tend to think of myself as an above-the-waist doctor. But sending oxygen in the back entrance, if it is shown to work, could be useful in a few cases."
One example is when doctors need to put a tube down someone's throat to hook them up to a ventilator. The process takes mere minutes. Yet in that time, patients can suffer dangerously low oxygen levels. If sending oxygen up the anus works, it might sustain patients for the short time it takes to get them on life support. That would be huge. Takebe also imagines intestinal oxygen as an add-on to other types of breathing support. It could also be a short-term solution when other treatments are not available. "Maybe we can apply this in emergency situations," he says. "For instance, when someone is on the way to the hospital. Or when they are being transferred from one hospital to another." But that future would still be many years and clinical trials away.
In the meantime, how does Takebe's father feel about butt breathing as a way to help patients like him? "Dad is pleased," Takebe says. "He is always offering to be our experimental subject." That would of course be a conflict of interest, Takebe adds. But he appreciates his dad's support.