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IBS treatment is a topic hits close to home for me. Working on the gastrointestinal surgery floor as a nurse, I witnessed firsthand the struggles of dealing with chronic abdominal pain. At the same time, I was dealing with my own challenges related to IBS. It was not the same, but there were definitely nights when I wished I could swap my problems for a condition that could be sorted out with surgery. The tricky part with IBS is that, unlike some other conditions, there aren't specific problems that surgeons can cut out and fix. Plus, the reasons behind the pain aren't well understood enough for medications to target effectively. It's a tough journey that takes a toll on both individuals and society (1).
When I was trying to find a solution for my IBS, I kept bumping into recommendations for the low FODMAP diet. It seemed like the one thing in my doctor's toolkit that might offer some relief. So, I committed to this diet for a month, but to my disappointment, it didn't do much for me. Eventually, I learned more about its effects on the gut microbiome and overall health, and I'm now grateful I didn't stick with it.
Understanding Low-FODMAP Diets and Their Mechanism
Low-FODMAP diets are all about cutting down on fermentable carbs – think oligosaccharides, disaccharides, monosaccharides, and polyols. It's a mouthful, I know! These are the carbs that resist digestion in the small intestine and reach the large intestine, where they get fermented by bacteria, causing gas and bloating (2). The idea is to eliminate the trigger – no food for the bacteria to ferment means no bloating.
It sounds good for managing symptoms in the short term, but here's the catch: this diet might make underlying issues worse in the long run – things like dysbiosis, an overactive immune system in the gut, and enzyme deficiencies (1,3). This is a bigger concern when people aren't properly told that low-FODMAP diets are meant to be temporary. Some folks end up following them forever, or worse, they start removing more foods they think are causing issues, ending up with a diet even lower in dietary fiber (4).
The Pitfalls of Low-FODMAP Diets
Fiber-loving gut bugs play a crucial role in producing short-chain fatty acids (SCFAs), which are like superfood for the cells lining the large intestine (7). They make up to 70% of what those cells need to survive. And guess what? They're only produced when our gut microbes munch on fiber. So, by starving these microbes, we're inadvertently starving our own cells. These SCFAs are also important signalling molecules for our immune system, protecting us from infection and helping prevent food sensitivities, allergies, and autoimmune issues (13).
To make matters worse, when we starve these fiber-loving microbes, they can be replaced by protein-eating microbes, which can start to eat away at our intestinal lining (2). A significant shift from friendly to not-so-friendly microbes can happen in just two weeks on a low-carb diet (5). So now, our gut cells are not only hungry but also at risk of being eaten alive. That's not exactly a recipe for a healthy gut.
To add insult to injury, a combo of low gut cell food, attacks from protein-eating microbes, and low immune-calming SCFAs can lead to increased "leaky gut," opening the door to issues beyond gut health, like inflammation and autoimmune problems. Understanding the connection between gut function and our microbes makes it clear why IBS is linked to increased intestinal permeability (6).
So, are low-FODMAP diets really the best option for healing the gut in IBS? As a short-term tactic for symptom relief, this diet may be a useful tool, but in the long term, it is clearly not health-promoting.
A Better Approach
Instead of sticking to an indefinite elimination diet like low-FODMAP, a smarter approach is a gradual increase in fiber over time. This works to shift microbial populations in the gut towards supporting gut health. To ease digestive symptoms, the focus should be on feeding our gut microbes, not starving them.
And if you’re worried about digestion (which is 100% understandable), let me reassure you. Despite what you’ve been led to believe, fiber is truly a friend, not a foe in this department! Humans have a limited number of enzymes to break down complex carbs (only 17), and none of them can handle fiber. But guess who can? Our gut microbes! They produce thousands of digestive enzymes that can break down all sorts of complex carbs and fiber, releasing beneficial nutrients and compounds that we wouldn’t otherwise have access to (8). So, instead of starving these microbes, we should be feeding them to boost their numbers and help us out. Fiber, it turns out, is crucial to feed our gut bugs, which then help us with its digestion – Talk about a symbiotic relationship!
Once we get our fiber-loving microbes thriving, they'll produce more gut-health-promoting SCFAs for us. These SCFAs are anti-inflammatory, support our intestinal barrier, increase nutrient absorption, and help normalize gut transit time (9, 10, 11). They also make the colon slightly acidic, preventing harmful bacteria growth and dysbiosis - addressing the proposed root cause of IBS (11, 1, 3). By reducing inflammation, they even help decrease visceral hypersensitivity – targeting the nervous system component of IBS pain.
Need a Plan?
If you're grappling with IBS and want a plan that not only tackles your symptoms but also sets you on a path to long-term gut health, I've got your back! I'd love to help you understand the cause of your digestive symptoms and create a nutrition and supplement plan for a resilient gut. If you have any questions, feel free to reach out - I’m here for you.
To your health,
Karen
Research:
1 - Adriani A, Ribaldone DG, Astegiano M, Durazzo M, Saracco GM, Pellicano R. Irritable bowel syndrome: the clinical approach. Panminerva Med. 2018 Dec;60(4):213-222. doi: 10.23736/S0031-0808.18.03541-3. Epub 2018 Sep 24. PMID: 30257542.
2 - Spiller R. Impact of Diet on Symptoms of the Irritable Bowel Syndrome. Nutrients. 2021; 13(2):575. https://doi.org/10.3390/nu13020575
3 -Ford AC, Sperber AD, Corsetti M, Camilleri M. Irritable bowel syndrome. Lancet. 2020 Nov 21;396(10263):1675-1688. doi: 10.1016/S0140-6736(20)31548-8. Epub 2020 Oct 10. PMID: 33049223.
4 -Altomare A, Di Rosa C, Imperia E, Emerenziani S, Cicala M, Guarino MPL. Diarrhea Predominant-Irritable Bowel Syndrome (IBS-D): Effects of Different Nutritional Patterns on Intestinal Dysbiosis and Symptoms. Nutrients. 2021 Apr 29;13(5):1506. doi: 10.3390/nu13051506. PMID: 33946961; PMCID: PMC8146452.
5 - Mahesh S. Desai et al., “A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility,” Cell 167, no. 5 (17 2016): 1339-1353.e21, https://doi.org/10.1016/j.cell.2016.10.043.
6 - Olivier, C. E. (2022). Considering Intestinal Hyperpermeability and Immune-Inflammatory Metabolism in the Treatment of Food Allergy. European Journal of Clinical Medicine, 3(3), 13–18. https://doi.org/10.24018/clinicmed.2022.3.3.207
7 - W. E. Roediger, “Utilization of Nutrients by Isolated Epithelial Cells of the Rat Colon,” Gastroenterology 83, no. 2 (August 1982): 424–29.
8 - Abdessamad El Kaoutari et al., “The Abundance and Variety of Carbohydrate-Active Enzymes in the Human Gut Microbiota,” Nature Reviews. Microbiology 11, no. 7 (2013): 497–504, https:// doi.org/10.1038/nrmicro3050.
9 - Harry J. Flint, Karen P. Scott, Sylvia H. Duncan, Petra Louis & Evelyne Forano (2012) Microbial degradation of complex carbohydrates in the gut, Gut Microbes, 3:4, 289-306, DOI: 10.4161/gmic.19897
10 - S. Srinivasan and J. W. Wiley, “New Insights into Neural Injury, Repair, and Adaptation in Visceral Afferents and the Enteric Nervous System,” Current Opinion in Gastroenterology 16, no. 1 (January 2000): 78–82;
11 - Sylvia H. Duncan et al., “The Role of PH in Determining the Species Composition of the Human Colonic Microbiota,” Environmental Microbiology 11, no. 8 (August 2009): 2112–22, https://doi. org/10.1111/j.1462-2920.2009.01931.x.
12 - Valdes, A. M., Walter, J., Segal, E., & Spector, T. D. (2018). Role of the gut microbiota in nutrition and health. BMJ, k2179. doi:10.1136/bmj.k2179
13 - Pamela V. Chang et al., “The Microbial Metabolite Butyrate Regulates Intestinal Macrophage Function via Histone Deacetylase Inhibition,” Proceedings of the National Academy of Sciences of the United States of America 111, no. 6 (February 11, 2014): 2247– 52, https://doi.org/10.1073/pnas.1322269111.
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