Gravity could be the culprit behind irritable bowel syndrome (IBS), according to a new hypothesis. Yes, the force that keeps our feet planted firmly on the surface of the Earth could be responsible for a condition that is thought to affect up to 10 percent of the world's population.
It may seem out-there, but to author Dr Brennan Spiegel, director of Health Services Research at Cedars-Sinai Medical Center, the influence of gravity on our bodies is an untapped well of scientific discovery.
“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 said in a statement.
Despite the prevalence of IBS, and the fact that it was first described over 100 years ago, there is still no consensus on what actually causes it. One theory, backed up by the apparent effectiveness of psychological therapies, is that IBS results from dodgy communication between the gut and the brain. Another possible explanation implicates the gut microbiome, the unique collection of bacteria living within each of our digestive systems. There’s even been a suggestion that the pain that sufferers experience could all be down to itchy guts.
This lack of a unifying explanation is a source of frustration for those living with the often life-altering symptoms of IBS. Without a better understanding of the causes of the condition, there is little hope for a cure for the constipation, diarrhea, pain, bloating, and cramping that sufferers have to put up with.
So, the gravity hypothesis could be a welcome new avenue to explore.
“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 started to make sense.”
The collection of organs and tissues that make up the digestive system are a heavy load, and gravity can drag us down, causing some of these organs to shift from their normal positions. The body has an inbuilt suspension system that counteracts the worst of these effects, but some people are better adapted to cope with gravity than others. Failure of these suspension systems, the theory goes, could lead to a variety of musculoskeletal and digestive problems, including IBS.
It's not just about the physical, though. Take the example of a rollercoaster. Some people are the throw-your-hands-up, scream-in-delight types, while others are gritting their teeth and cowering in fear (me, I’m firmly in the latter camp). This spectrum of responses to the G-force we experience on rides or during a turbulent flight is what Spiegel has termed “G-force vigilance.”
“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.”
Spiegel even suggests that abnormal serotonin, another potential contributor to IBS, could be due to gravity intolerance.
Abdominal distress caused by one of the fundamental forces of the universe may not have been on your bingo card for 2022. However, the beauty of this new hypothesis, according to Women's Guild Chair in Gastroenterology and director of the Division of Digestive and Liver Diseases at Cedars-Sinai, Dr Shelly Lu, is that it can be tested experimentally. “If proved correct, it is a major paradigm shift in the way we think about IBS and possibly treatment as well.”
With the sheer variety of symptoms it causes, it’s possible we will never have one single explanation for IBS. It’s much more likely that a combination of factors are involved. But, if anyone does fancy running a clinical trial in the low-gravity environment of outer space, you can certainly sign me up.
The study is published in The American Journal of Gastroenterology.