Why Are Gut Problems So Common in hEDS? Connective Tissue and Motility
Gut symptoms are common in hEDS and HSD. What studies found about connective tissue, POTS and motility, the SIBO link, and what to bring to a GI visit.
Photo: Illia Bondar / Unsplash
Why are gut problems so common in hypermobile Ehlers-Danlos syndrome (hEDS)? hEDS is an inherited connective tissue condition whose main feature is joints that move further than usual. Connective tissue is the material that holds the body's structures together. The gut wall is built from it too, along with muscle and nerves that can work differently in hEDS. In a 2020 cohort, about six in ten people with hEDS already had gut symptoms at diagnosis. Of the ones who had motility testing, about three in four had a motility problem. Motility means the muscle contractions that move food and waste through the gut.
In that cohort, about two-thirds of those with a confirmed motility problem had it diagnosed before their hEDS. Half of those waited 39 months or longer, more than three years, between the motility diagnosis and the hEDS diagnosis.
How common are gut problems in hEDS?
Mohammad Alomari and colleagues at the Cleveland Clinic reviewed the charts of 218 people diagnosed between 2007 and 2017 who met the 2017 international hEDS criteria. At diagnosis, 136 of them (62.3%) had at least one gut symptom. The most common were abdominal pain (49.8%), nausea (49.5%), and constipation (45.4%), each affecting roughly half.
Only 42 had motility testing, and 32 of them (76.2%) had some form of dysmotility. Dysmotility means gut contractions that don't move contents along at a normal pace. Gastroparesis was the most common category, in 18 of the 42. Gastroparesis usually means the stomach empties too slowly without a blockage, although in this group's gastric emptying studies 12 people had slow emptying and 6 had emptying that was faster than normal. Five had esophageal dysmotility, five had altered transit through the small bowel or colon, and four had dysmotility along the whole gut. A third of the cohort (33.9%) also had a history of pelvic floor dysfunction, meaning trouble coordinating the muscles used to pass a bowel movement. The study had no comparison group, and the authors acknowledged in the paper's discussion that only a minority of the cohort had motility tests, so the true rate of dysmotility in hEDS couldn't be pinned down.
Ching Lam and colleagues ran a UK survey with a comparison group: 603 people with hEDS or hypermobility spectrum disorder (HSD), and 603 age- and sex-matched people from the general population. HSD is the broader term for symptomatic joint hypermobility, including people who don't meet the full hEDS criteria. In the hypermobility group, 98% met symptom criteria for at least one functional gut disorder, nearly everyone, compared with 47% of controls, a little under half. Functional gut disorders are recognized patterns of gut symptoms without structural damage to explain them. When the researchers accounted for how many symptoms each person had outside the gut and joints, the association was reduced by as much as fourfold and in some cases disappeared.
Why would connective tissue affect the gut?
In hEDS, connective tissue is usually more stretchy and less stable, well beyond the joints. In a 2022 review written for gastroenterologists, Phoebe Thwaites and colleagues at Monash University sorted the proposed explanations into three groups in their section on what contributes to these symptoms. The first is the physical effect of looser, weaker connective tissue, and the second is the change in gut function that follows from it. The third covers influences from outside the gut, including autonomic dysfunction, medication effects, and mental health conditions. Autonomic dysfunction means the nerves that control automatic functions like heart rate and digestion aren't working normally. The authors added that evidence for all three is still limited.
Where POTS and the nervous system come in
POTS stands for postural orthostatic tachycardia syndrome. The Cleveland Clinic authors defined POTS as the heart rate rising by 30 beats a minute or more within 10 minutes of standing, while blood pressure stays steady. Of their cohort, 40% had POTS, so two in five. It was the one factor still linked to dysmotility after the researchers accounted for the others, with 5.74 times the odds of a dysmotility diagnosis. Odds compare how often something happens with how often it doesn't, so the odds were nearly six times higher with POTS. The range around that estimate was wide, from about 2 to 17 times, and because this was a chart review, the study can't show that POTS causes the motility problem.
In my view, motility and the nervous system are a big part of the story once hypermobility is involved. When the body spends long stretches in a fight-or-flight state, digestion is not a priority, and gut motility can slow down a lot. Gut symptoms that get worse when you stand can be part of POTS, so it helps to know if you have both.
Thwaites and colleagues noted that inflammatory and body-wide symptoms are also reported in hEDS, and that these have been proposed to relate to mast cell activation. Mast cell activation syndrome (MCAS) is a condition where mast cells release inflammatory chemicals too easily, and how common MCAS is in POTS and hEDS is its own question.
Motility, and why SIBO can keep coming back
Small intestinal bacterial overgrowth (SIBO) means more bacteria live in the small intestine than should. I think motility is the most important part of treating SIBO. Slow motility gives bacteria a chance to build up, and the overgrowth can then slow motility further. Clearing the bacteria without improving motility usually means SIBO comes back. Between meals, the stomach and small intestine have a repeating cycle of contractions called the migrating motor complex (MMC), and eating interrupts it. In a 2012 review, Eveline Deloose and colleagues wrote that an absent MMC has been associated with SIBO, though its role is still incompletely understood. Stress affects the MMC as well. Small intestine and large intestine motility are separate systems, so a daily bowel movement doesn't mean the small intestine is clearing itself between meals.
Researchers haven't established that hEDS causes SIBO. In the Cleveland Clinic cohort, 16 people had a hydrogen breath test and 5 came back positive. The authors cautioned that breath testing has considerable limitations when someone has dysmotility.
What to bring to a gastroenterologist
Thwaites and colleagues wrote in their management section that evidence here is limited and no single approach fits everyone. I'd bring these to a GI visit:
- A symptom timeline: when your gut symptoms started, which came first, and how they've changed alongside joint pain, fatigue, or dizziness.
- Whether your gut symptoms get worse after standing for a while, since that can be part of POTS.
- Your hEDS or HSD diagnosis, who made it, and which criteria they used. hEDS has formal criteria, so being very flexible isn't a diagnosis on its own.
- Every gut test you've already had, with dates and results, such as breath tests, gastric emptying studies, endoscopies, and celiac blood work.
- Your full list of medications, since some of them can slow the gut.
The review's checklist also includes screening for celiac disease and inflammatory bowel disease, as for anyone with long-term gut symptoms, so it makes sense to check with your doctor that those have been ruled out.
If you want a structured walk-through of SIBO treatment, the SIBO Treatment Algorithm lays out the treatment options, what to do when symptoms don't improve or come back, gentler routes for people who are more sensitive, and the gut and motility repair that comes after.
FAQ
Does hEDS cause SIBO?
Researchers haven't established that hEDS causes SIBO. Motility problems are common in hEDS, and slow motility gives bacteria a chance to build up in the small intestine, so the two can be connected through motility. In a 2020 Cleveland Clinic cohort, only 16 people had a breath test, and the authors noted that breath tests have considerable limitations when motility is abnormal.
What kinds of motility problems are found in hEDS?
In a 2020 cohort of people meeting the 2017 hEDS criteria, 32 of the 42 people who had motility testing had some form of dysmotility. Gastroparesis was the most common category the authors reported, although their gastric emptying studies found slow emptying in 12 people and faster-than-normal emptying in 6. Others had esophageal dysmotility, altered transit through the small bowel or colon, or dysmotility along the whole gut, and about a third of the full cohort had a history of pelvic floor dysfunction.
Is POTS connected to gut symptoms in hEDS?
In that same cohort, POTS was the one factor still linked to dysmotility after the researchers accounted for the others, with 5.74 times the odds of a dysmotility diagnosis. The study was a retrospective chart review, so the researchers couldn't establish that POTS causes the motility problem.
What is the difference between hEDS and HSD?
Hypermobility spectrum disorder (HSD) is the broader term for symptomatic joint hypermobility, and it includes people who don't meet the full hEDS criteria. hEDS is at the more severe end of that spectrum. There is no genetic test for hEDS yet, so the diagnosis is made from clinical criteria.
Should I mention hypermobility to my gastroenterologist?
If you have joint hypermobility and ongoing gut symptoms, it's reasonable to bring it up. A 2022 review written for gastroenterologists suggests screening for hEDS with a short five-question questionnaire and considering the diagnosis in people with gut-brain interaction disorders and symptoms in several body systems.
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