With discussion around complex chronic illnesses like Mast Cell Activation Syndrome, POTS, Ehler’s Danlos Syndrome, Lyme Disease, Long COVID and others dominating the health landscape lately, including in my own clinical practice, long-recognized conditions like Irritable Bowel Syndrome (IBS) are slowly being pushed lower on the totem pole in conversation and in research.
Fortunately for the more than 11% of the global population who suffer from IBS, a new peer-reviewed literature review by Siraj et al, “Bacterial Histamine as a Therapeutic Target for Abdominal Pain in Irritable Bowel Syndrome” published in April’s edition of The Cureus Journal of Medical Science not only reminds us of the importance of keeping this notoriously nebulous condition on the forefront of our minds, but also makes a key link between the root causes of IBS and some of the aforementioned complex conditions. This is a major throughline as we continue to seek best treatment practices for debilitating gastrointestinal symptoms that span multiple diagnoses and tend to evade long-term relief.
It’s important to note that IBS is a functional GI disorder (FGID) of the brain-gut axis, as defined by Rome IV Criteria, that produces disruptive but not life-threatening symptoms like abdominal pain, intestinal gas, bloating/distention, and altered bowel habits. People who suffer from IBS, notably young women, typically endure a lower quality of life, increased depression, and poor body image.
Histamine, a chemical mediator secreted from immune cells in the body, including mast cells, in response to external stimuli, is responsible for a wide variety of actions across all organ systems, including the gastrointestinal system, where it regulates GI motility, gastric acid secretion, and mucosal ion transport through 4 distinct histamine receptors. The literature review notes that pharmacological inhibition of the H4R Receptor in the gut reduces visceral hypersensitivity (a hallmark of IBS) and decreases mast cell infiltration in the colon. The authors note, “Individuals with IBS have elevated levels of mast cells in the colon, often near enteric [intestinal] nerves, which correlates with the severity of abdominal pain. There is also a higher occurrence of histamine-producing bacteria.” In particular, gut-specific histamine-producing bacteria include Bacteriodes, Blostridium, Bifidobacterium, Fusobacterium, and Lactobacillus.
In a fascinating conclusion, the authors go on to say that, “These findings suggest that gas production and bowel distention are not the primary causes of pain in IBS patients on high fermentable diets [high-FODMAP diets],” but that it is instead the action of gut histamine activity that increases visceral hypersensitivity. In the eating disorder field, studies like this become key when implementing dietary strategies so that clients are not unnecessarily limited from eating foods that may not have a negative impact in the first place, and in fact may deprive them of key nutrients, like fiber, that are actually responsible for gut repair and optimal functioning.
While these correlations and connections provide rich material for developing treatment strategies for IBS and other conditions that span the GI-symptom/histamine continuum, it’s vital to keep in mind that this is emerging science. Anyone who tells you with certainty that simply following “3 easy steps” will rebalance your gut is likely optimistic at best and trying to sell you something at worst. It’s important to allow the science to catch up with practice and work closely with your clinician to determine the best dietary approach for you, with room for experimentation and patience along the way.
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