There is no official cause for irritable bowel syndrome (IBS), but for one gastroenterologist, the answer has been right under our noses. A review published today in The American Journal of Gastroenterology posits that the all-too-common ailment is caused by the forces of gravity. The unconventional hypothesis suggests the human body has evolved to live with this universal force, and when our ability to manage gravity falters, it can have dire ramifications on our health.
“Our relationship to gravity is a little bit like a fish’s relationship to water,” says Brennan Spiegel, a gastroenterologist at Cedars-Sinai Medical Center in Los Angeles and author of the new paper. “The fish evolved to have a body that survives and thrives in water, even if it may not know it’s in water to begin with.” Similarly, Spiegel explains that while we aren’t always conscious of gravity, it’s a constant influence on our lives. For example, our early human ancestors evolved to become bipedal organisms, spending two-thirds of their lives in an upright position. But standing erect would cause gravity to constantly pull our body system down toward the ground, meaning organs and other bodily systems must have a plan in place to manage and resist gravitational forces. (For example, mammalian brains have evolved ways to sense altered gravity conditions.)
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Spiegel says he thought about the gravity hypothesis in relation to IBS when visiting a sick family member at an assisted living center. Lying in bed for most of the day, he noticed an increase in GI problems during her stay, including constipation, bloating, and abdominal pain, making him evaluate whether lying down all day changes a person’s relationship to the force of gravity. “Why is it that she’s not able to move her intestines as well as she could before,” he first questioned.
Think of the GI tract as a sack of potatoes. Humans internally lug around this sack their whole lives, though Spiegel argues that some people’s body compositions are better suited to carry that sack around better than others. But according to Newton’s Third Law (for every force in nature there is an equal and opposite reaction), because gravity is pulling our body down, our body’s must have “antigravity” mechanisms in place to stabilize organs. This support comes from musculoskeletal structures like the spine and mesentery that works as an internal suspension system to hold the intestines in place. What’s more, the rib cage along with the spine helps to secure the position of the diaphragm, which acts as a ceiling mount to suspend organs in the upright abdominal cavity. All together, these structures work as a crane to stabilize and keep the organs in place.
The gravity hypothesis is not meant to disprove other ideas on what causes IBS, but rather, a way to tie in all them into a concise explanation.
But what happens when the antigravity mechanisms in our body fail? You’ll see symptoms very similar to those who have IBS, according to the research paper. When the musculoskeletal system is not aligned with gravity, it’s not capable of completely resisting this force of attraction. The mismatched strain between attractive and repulsive forces would theoretically cause tension in the body, resulting in muscle cramping and pain from being unable to properly support the contents in the abdomen. Additionally, excess pressure on the spine from trying to stabilize sagging structures would cause intense back pain. Finally, if the abdominal crane starts to sag and loosens its hold, the pull of gravity would cause the organ to move out of place, pushing the GI tract forward and giving little space for food to move in and out of the tract. All of these changes may compound in IBS symptoms.
One point Spiegel emphasizes is that the gravity hypothesis is not meant to disprove other ideas—two popular ones being that IBS is caused by changes in the gut microbiome or from elevated serotonin levels—but rather, a way to tie in all them into a concise explanation.
“Intestines fall under the force of gravity, and they can develop a problem where they kink up almost like a twisted garden hose that makes it hard for water to get through,” Spiegel says. “As a result, they get bacterial overgrowth, and they get abdominal pain and gassiness.”
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Julie Khlevner, a gastroenterologist at the NewYork-Presbyterian Morgan Stanley Children’s Hospital who was not affiliated with the research, says that while the gravity hypothesis is less conventional than other prevailing theories for IBS, it has been previously used to explain other diseases like amyotrophic lateral sclerosis. “Although [it’s] thought provoking and theoretically compatible with the clinical manifestations of IBS, it remains in its hypothetical stage and requires further research,” she cautions. “For now, the currently accepted concepts in pathophysiology of IBS [alterations in the bidirectional brain-gut-microbiome interaction] will remain the pillars for development of targeted therapies.”
If Spigel is right about his rationale, he could be onto something bigger. Understanding how gravity alters our bodily functions could help find answers on why certain exercises, such as yoga and tai chi, can relieve GI symptoms by strengthening musculoskeletal muscles and the anterior abdominal wall. Or why people experience more stomach problems at high altitudes like when climbing up mountains, or more generally, why women are disproportionately affected by IBS. Spiegel already has an explanation for the last issue (he says women have more elastic internal structures than men, including floppier and longer colons that are more susceptible to the pull of gravity), but he’s hoping others will pursue the same line of work and help bring relief to the millions of people living with IBS everyday.
