Irritable bowl syndrome impacts up to 16% of the US population. A syndrome is a collection of symptoms that regularly happen together. For instance, to be diagnosed with IBS, one mush have a few of the following: Pain, cramping, bloating, loose stools or constipation. Also, this has to go on for a few months to be “officially” IBS. And, your doc will have to have ruled out a structural- or disease-related cause. So it comes down to process of elimination. Beyond that, such symptoms can have many causes. And the ultimate cause of IBS isn’t known. Frustrating, huh?
A little clarification…IBD may just be one letter different than IBS, but IBD is quite different than IBS. IBD stands for Irritable Bowel Disease, and includes life threatening diseases such as Crohn’s Disease and Ulcerative Colitis.
OK, back to IBS. So, if we don’t know what causes IBS, does that mean there is nothing we can do? It used to be believed that IBS was caused by stress, and therefore, would be “cured” by chilling out. We know now that the gut and brain do communicate in numerous ways, such as through vagus nerve signaling and through neurotransmitters. We even have what’s regarded as a “second brain” in our gut: The enteric nervous system. So all those gut feelings you have? Perhaps that’s your second brain talking to you! So, maybe both brains need to chill out? Probably, but it has been shown that IBS is not just “in our head.”.
Although IBS isn’t life-threatening, it can be annoying and damned inconvenient when you’re trying to get out of the house and you have to keep running back to the bathroom.
Besides stress, other potential triggers for IBS include genetics, food sensitivities, environmental factors, and infectious gastroenteritis (“itis” means inflammation, the rest means digestive tract). Even Leaky Gut Syndrome <link to this blog post>, which we explored in an earlier post, may be a trigger.
Research is actually finding that this inflammation communicates with the brain via the vagus nerve we mentioned, and may even worsen or trigger anxiety or depression. Those feelings can heighten sensitivity to IBS, forming a vicious cycle of symptoms. In fact, some research is finding that about half of the cases of IBS start in the gut, and then cause psychological stress, rather than starting in the head and making their way down to the gut.
While a grad student and then a postdoctoral fellow, I was intimately familiar with IBS. I attributed it to the stress that went along with being in the research world, but now wonder how much the pasta, bread, coffee and wine diet I lived on drove the symptoms. And how much the anxiety I experienced originated in the gut rather than in the lab.
Some studies are finding that fiber in the diet may help with IBS symptoms. Fiber is the part of plant-based foods that we don’t digest (though our gut flora can). But, hold the bus….don’t run out and start swallowing huge amounts of chard, a high fiber food. You have to ease into it if coming from a low fiber diet. Also, whether fiber is helpful may depend on the type of fiber. For example, a study looking at insoluble fiber such as bran found that insoluble fiber may actually worsen some IBS symptoms. Unlike soluble fiber, which dissolves into a gel in the gut, insoluble fiber doesn’t dissolve. Insoluble fiber is important, in the long run, for our health so limiting it is not something you want to do forever. Just until the IBS eases up.
In contrast to insoluble fiber, soluble fiber may be helpful for IBS symptoms. But, the caveat is that foods rich in soluble fiber need to be those that are low in (ready for this?) “fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs). What the h-ll are these? They’re small carbohydrates that are readily fermented by our gut microbes and, as such, may worsen IBS symptoms. Sugars such as lactose (in dairy) and fructose (in fruits) are FODMAPs you may have heard of. You may have encountered the sweeteners mannitol and xyletol, these are FODMAPs of the polyol kind.
So, what are some foods high in soluble fiber but relatively low in FODMAPs? Quinoa, bananas, carrots, chickpeas, Brussels sprouts, eggplant, sunflower seeds, nuts (excluding cashews and pistachios) and potatoes (with peel). Tolerance of fiber is variable in people with IBS. As mentioned, go slowly when adding it in. The goal is 25-30 grams daily from food, but back off if it’s symptom provoking rather than symptom-relieving.
Red flags that may indicate something more serious than IBS is going on include fever, blood in stools, weight loss, recent antibiotic usage, symptom onset after 50 years of age, being woken from sleep due to symptoms, symptoms that get progressively worse, or a familial history of IBD or colon cancer.
Further reading for your nerding pleasure…
Pimental, M (2018) Evidence-Based Management of Irritable Bowel Syndrome With Diarrhea. American Journal of Managed Care. 24:S35-S46. https://ajmc.s3.amazonaws.com/
_media/_pdf/AJMC_A793_IBSd__ Evidence%20Based%20Management% 20of%20IBSd.pdf
El-Salhy, M, et al (2017) Dietary fiber in irritable bowel syndrome (Review). International Journal of Molecular Medicine. 40(3): 607–613. https://www.ncbi.nlm.nih.gov/
Thalheimer, JC (2016) Fiber & Irritable Bowel Syndrome — Strategies for Counseling Patients. Today’s Dietician. 18(8):34. https://www.todaysdietitian.