New Study Suggests an Imbalance of Gut Bacteria Might Be Linked to Restless Leg Syndrome
Experts say treating the overgrowth of harmful bacteria might help people with the sleep disorder.
People with restless leg syndrome may have unusually high levels of bacteria residing in their gut. That’s the conclusion of a new Stanford University study, published in the April 2019 issue of the journal Sleep and presented yesterday, June 9, 2019, at SLEEP 2019, the annual meeting of the Associated Professional Sleep Societies.
A team from the Stanford Center for Sleep Sciences and Medicine in Redwood City, California, collected stool and breath samples from seven people diagnosed with moderate to severe restless leg syndrome (RLS). An analysis of those samples revealed that all seven people had a gut condition known as small intestinal bacterial overgrowth, or SIBO.
SIBO is a condition in which a person has an overabundance of bacteria in the upper portion of their gut. The excess bacteria also tend to be relatively uncommon types. Depending on the digestive functions these bacteria perform, having too much of them can cause a range of gut symptoms — from gas and bloating to diarrhea, stomach pain, and nausea, previous research has shown.
While estimates vary, SIBO normally turns up in just 15 percent of people. So the new study’s finding that SIBO was present in all seven of the patients with RLS was noteworthy.
“Restless leg syndrome is a condition that is often misunderstood by the public,” says Michael Grandner, PhD, director of the Sleep & Health Research Program at the University of Arizona in Tuscon, who was not involved with the new study. “It involves problems with discomfort in the legs that typically occur at night, and it results in the patient needing to move around in order to quiet these uncomfortable sensations.” (It’s this need to move that makes it hard for people with RLS to sleep.)
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Dr. Grandner says that during the past several years studies of the gut microbiome have uncovered numerous links between this complex ecosystem in the intestines and a large number of health conditions. “This study showed that some aspects of gut bacteria might be related to the symptoms of restless leg syndrome,” he says.
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Iron Availability in the Brain Might Explain This SIBO-RLS Relationship
“Chronic inflammation caused by SIBO or gut dysbiosis [when there’s an unhealthy balance of types of gut bacteria] in the colon may release additional hepcidin — a hormone that can decrease iron availability in the brain and contribute to RLS,” explains Daniel Jin Blum, PhD, first author of the new study and an adjunct clinical instructor at the Stanford University School of Medicine in California.
Past research has shown that iron deficiency in the brain is a major risk factor for RLS. “[RLS] involves the interface between the brain and muscle systems, and in many people it involves the biochemistry of how the body manages iron levels,” Grandner says.
While the relationship between RLS and iron deficiency isn’t well understood, there’s some evidence that low iron stores in the brain play a role in the function of its dopamine receptors, which in turn may affect brain communication and signaling in ways that contribute to RLS, according to resources from Johns Hopkins University.
Does that mean upping iron intake can help with RLS? Unfortunately, eating oysters or other iron-rich foods probably won’t do much for someone with RLS. Experts have found that, in patients with RLS, the brain’s iron stores can be depleted even if the person’s blood and dietary levels of iron are normal.
Could Rebalancing Gut Bacteria Help RLS?
The new Stanford findings suggest that, potentially, treating a person’s SIBO may help resolve the brain iron deficiency that contributes to RLS. But a lot more research is needed. “Since these are quite new findings, we will still need to see whether this relationship can be replicated, and whether it somehow interacts with the neuromuscular and iron-related pathways involved in restless legs syndrome,” Grandner says.
It's also important to note that this study was preliminary and only included a small number of study participants: seven people.
How do doctors treat SIBO? Dr. Blum says drugs that treat acid reflux, known as prokinetics, may help some people with SIBO. Certain eating patterns — including finishing the last meal of the day at least two to three hours before bedtime — may also help, he says. But he says these and other treatment options should only be tried with a doctor’s supervision. And it’s important to highlight that research has not yet made clear whether or not treating SIBO will help people with RLS. (The new findings simply suggest this treatment strategy could work, and is likely worth studying.)
Long story short, there are still a lot of unknowns when it comes to the interaction between the brain, the gut, and restless legs syndrome. This study may end up adding a piece to the puzzle, but the picture is far from complete.