HQ Team
December 2, 2022: Irritable bowel syndrome (IBS), a gastrointestinal disorder that affects up to 10% of the global population, may be caused by gravity, a new theory suggests.
The syndrome, and many other conditions, could develop due to the body’s inability to manage gravity, according to Brennan Spiegel, director of Health Services Research at Cedars-Sinai and author of the hypothesis.
“As long as there’s been life on Earth, from the earliest organisms to homo sapiens, gravity has relentlessly shaped everything on the planet,” said Spiegel, a professor of medicine.
“Our bodies are affected by gravity from the moment we’re born to the day we die. It’s a force so fundamental that we rarely note its constant influence on our health.”
Spiegel’s theory, published in the American Journal of Gastroenterology, describes how the intestines, spine, heart, nerves and brain evolved to manage gravity.
‘Pulled downward’
“Our body systems are constantly pulled downward,” Spiegel said. “If these systems cannot manage the drag of gravity, then it can cause pain, cramping, lightheadedness, sweating, rapid heartbeat and back issues—all symptoms seen with the syndrome.
“It can even contribute to bacterial overgrowth in the gut; a problem also linked to irritable bowel syndrome.”
Experts are still in the dark about how or why the syndrome develops. Some scientists say it is a gut-brain interaction disorder. Others suggest that abnormalities drive the syndrome in the gut microbiome.
Motility abnormalities
Another set of theories focuses on abnormalities in motility, gut hypersensitivity, abnormal serotonin levels or a dysregulated autonomic nervous system that can also cause the syndrome.
“There’s such a variety of explanations that I wondered if they could all be simultaneously true,” said Spiegel.
“As I thought about each theory, from those involving motility to bacteria, to the neuropsychology of IBS, I realized they might all point back to gravity as a unifying factor.
“It seemed pretty strange at first, no doubt, but as I developed the idea and ran it by colleagues, it made sense.”
“Gravity can compress the spine and decrease one’s flexibility. It can also cause organs to shift downward, moving from their proper position.
‘Sack of potatoes
The abdominal contents are heavy, like a sack of potatoes that we’re destined to carry our entire lives,” Spiegel said.
“The body evolved to hoist this load with a set of support structures. If these systems fail, then IBS symptoms can occur along with musculoskeletal problems,” he said.
Some have bodies that are more capable of carrying the load than others. Others have spinal issues that cause the diaphragm to sag or the belly to protrude, leading to a compressed abdomen.
These factors might trigger motility problems or bacterial overgrowth in the gut. This may also explain why physical therapy and exercise are effective for IBS because these interventions strengthen the support systems.
The gravity hypothesis also goes beyond the intestines.
“Our nervous system also evolved in a world of gravity, which might explain why many people feel abdominal butterflies when anxious,” said Spiegel.
G-force detector’
“It’s curious that these ‘gut feelings’ also occur when falling toward Earth, like when dropping on a roller coaster or in a turbulent aeroplane. The nerves in the gut are like an ancient G-force detector that warns us when we’re experiencing—or about to share—a dangerous fall.
“It’s just a hypothesis, but people with IBS might be prone to over-predicting G-force threats that never occur.”
“This hypothesis is very provocative, but the best thing about it is that it is testable,” said Shelly Lu, the Women’s Guild Chair in Gastroenterology and director of the Division of Digestive and Liver Diseases at Cedars-Sinai.
“If proved correct, it is a major paradigm shift in how we think about IBS and possibly treatment.”