It seems pretty strange, but new research published today reveals how gravity may cause irritable bowel syndrome or IBS and the overgrowth of bacteria in the gut.

Gravity may be to blame for irritable bowel syndrome (IBS), the most prevalent GI condition, according to a new theory.

Brennan Spiegel, MD, MSHS, who wrote the hypothesis and is the director of Health Services Research at Cedars-Sinai, says that IBS and many other conditions could be caused by the body’s inability to deal with gravity.

“As long as there’s been life on Earth, from the earliest organisms to Homo sapiens, gravity has relentlessly shaped everything on the planet,” explains Spiegel, who is also 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.”

The theory, which was published in the American Journal of Gastroenterology, explains how the intestines, spine, heart, nerves, and brain evolved to deal with gravity.

“Our body systems are constantly pulled downward,” adds Spiegel. “If these systems cannot manage the drag of gravity, then it can cause issues like pain, cramping, lightheadedness, sweating, rapid heartbeat and back issues—all symptoms seen with IBS. It can even contribute to bacterial overgrowth in the gut, a problem also linked to IBS.”

Since IBS was originally diagnosed more than a century ago, experts have been perplexed by its underlying mechanism. Even though the condition affects up to 10% of people worldwide, researchers are still unsure of how or why it occurs.

But there are a number of different theories that try to explain its clinical features. The first is that IBS is a condition of gut-brain connection and that neuromodulators and behavioral therapy are beneficial. Another theory says that IBS is caused by changes in the microbiome of the gut, which can be fixed with antibiotics or diets that are low in fermentable foods.

Other theories say that IBS is caused by problems with gut motility, gut hypersensitivity, abnormal serotonin levels, or a nervous system that isn’t working right.

“There’s such a variety of explanations that I wondered if they could all be simultaneously true,” adds 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 started to make sense.” 

Gravity can put pressure on the back and make it less flexible. Additionally, it may cause organs to move from their ideal positions and slide downhill. Spiegel described the abdominal contents as being like a bag of potatoes that we must carry about with us for the rest of our lives.

“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,” Spiegel adds.

Some people have stronger bodies than others, so they can carry more weight. Some have “stretchy” suspension systems that make the intestines hang down, for example. Some people have back problems that cause the diaphragm to sag or the belly to stick out, which makes the abdomen smaller.

These elements may lead to bacterial overgrowth or motility issues in the stomach. This may also provide light on the efficacy of physical therapy and exercise in the treatment of IBS, since these therapies work by strengthening the support networks.

But the gravity theory is not just about the intestines.

“Our nervous system also evolved in a world of gravity, and that might explain why many people feel abdominal ‘butterflies’ when anxious,” adds Spiegel. “It’s curious that these ‘gut feelings’ also occur when falling toward Earth, like when dropping on a roller coaster or in a turbulent airplane. The nerves in the gut are like an ancient G-force detector that warns us when we’re experiencing—or about to experience—a dangerous fall. It’s just a hypothesis, but people with IBS might be prone to over-predicting G-force threats that never occur.”

Some people can handle G-forces better than others. For instance, when descending on a roller coaster, one person may raise their hands and smile while another person grinds their teeth and moans. The difference between the first person’s amusement and the second person’s sense of fear reveals a range of what Spiegel terms “G-force vigilance.”

Serotonin may also play a role. It is a neurotransmitter that may have evolved in part to help the body deal with gravity. According to Spiegel, serotonin is essential for mood enhancement in both metaphor and reality. Without it, people couldn’t stand up, keep their balance, move blood through their bodies, or pump their intestines against gravity.

“Dysregulated serotonin may be a form of gravity failure,” Spiegel adds. “When serotonin biology is abnormal, people can develop IBS, anxiety, depression, fibromyalgia, and chronic fatigue. These may be forms of gravity intolerance.”

Testing this strategy and the potential therapies will need further investigation.

“This hypothesis is very provocative, but the best thing about is that it is testable,” adds Shelly Lu, MD, 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 the way we think about IBS and possibly treatment as well.”

Source: 10.14309/ajg.0000000000002066

Image Credit: Getty