An overview of Sourdough Bread and IBS

It’s just IBS

When I first had digestive issues with bread, the first thing my GP told me was that it was “just IBS.” Over thirty-five years later, I can still hear the sting of those words. It’s just IBS. It wasn’t the initial diagnosis — it felts dismissive after my GP had ruled out other things first. He’d ruled out colorectal cancer, although in those days it wasn’t something that affected young people to the same extent it does now. He’s tested for coeliac disease, and found no inflammatory bowel disease. And once those had been crossed off the list, my GP had nowhere really to go.

In the early 1990’s IBS was a dismissal. Even now it isn’t really a diagnosis at all. It’s a collection of symptoms, and I felt helpless. To make matters worse he prescribed me peppermint oil which exacerbated the flares, and it coincided with depression and exacerbated social awkwardness. I remember sense of frustration and disempowered.

My own IBS recovery

I’ve heard some bakers claiming that their bread has “cured IBS.” I’m afraid you cannot cure IBS, and when I read this I was filled with a sense of horror that someone could say such a thing and not really understand how very misleading this kind of language is. At the same time, my in-house GP quipped that if she had cured IBS she really deserved a Nobel Peace Prize, and of course we all fell about laughing. That said, IBS isn’t a laughing matter. It is painful, unpredictable, emotionally wearing and oddly at times humiliating, as well as being invisible. I remember that the constant vigilance about food and bathrooms was so wearing, in a way that healthy people rarely understand.

You can, however, recover from IBS. It can still flare and I am mindful of being respectful of my triggers, but learning to nourish my gut and lower inflammation and stress were key.

It took a long time, and rhythm and routine, to recover. A large part of this was a gentle and steady rebuild back to a healthy gut, using bread as a fibre delivery system and fermentation to predigest it. As I learned about myself, I began teaching others — in the first instance almost accidentally. It was very much pre-internet, and I had to work for a whole weekend to earn enough money to purchase the studies that of course are now free and instantly available. But I was determined to use evidence in my approach, and these origin papers had priceless laboratory findings which I would apply. I’d spend hours experimenting with starter refreshments, timings and flours, sourness levels, and how much the bread needed to ferment to be digestible. It built a phenomenal level of tacit knowledge, and I extended that understanding of grains, bread, diversity, fermentation and gut health week on week, year on year. Even now, this month a new study has been published which gives us an even better insight into IBS, and into understanding why some people suffer and why.

So perhaps one of the most important things about discovering I could eat sourdough was the ability to comfortably digest bread again. I cannot overstate the joy that this brought, and how this shaped the way I approach gut health. I learned how to gently predigest my bread and build in fibre and diversity slowly, and it is this deep understanding that is the foundation to how I work with people now: baking slowly and building fibre slowly.

Sourdough let me enjoy eating something I love

So in this article I want to lean back into that revelation — that sourdough let me enjoy eating something I love, and also enjoy eating something as ordinary as a sandwich. You wouldn’t believe how important it became to be able to just eat a sandwich, or have a piece of toast. When it was taken away from me it wasn’t simply about being able to eat it. My identity as a baker had been stolen from me.

What I am hoping you will discover as you read this is that not all sourdoughs are created equal. Some are better than others. In fact, some commercial loaves that call themselves sourdough are so horrendous that, frankly, you may as well not eat them, because there has been no real transformation whatsoever. They are sourdough in name only. So don’t be surprised if not all sourdough is digestible. Here is a little more of an explanation, and by all means leave comments — I respond to them. Here’s the rest of what I think you will find interesting.

Sourdough and IBS: A Holistic Approach to Gut Health

IBS is the subject I am most often asked about when it comes to bread and digestion. It is a common condition worldwide, contributing significantly to gastroenterology consultations in the UK (Staudacher & Whelan, 2016). I notice that more women ask me about this than men, though men do have bloating and IBS too, and they often seem less willing to identify it. That is my observation, and bloating is the symptom most often reported when eating bread.

The estimated global prevalence is approximately 10% of people, though in western countries including the UK it is reported to be up to 20% of the population. So it is no surprise that IBS is the most common condition people tell me clears up when they begin fermenting their bread.

What has changed in the past few years is our understanding of why some people are so much more vulnerable than others. Large genome-wide association studies, including a recent meta-analysis of more than 65,000 IBS cases, have shown that genetics play a far more significant role than we used to believe. Heritability estimates sit somewhere between 5 and 13%, depending on which diagnostic criteria are used, and the genes involved cluster around shared pathways: the gut-brain axis, bile acid metabolism, cholinergic signalling, and even thiamine (vitamin B1) handling. This matters for those of you who have struggled for years and been told it is just stress, or just diet, or just nerves. It is rarely just anything. Your biology is part of the picture, and the picture is becoming clearer.

I want to explain that when it comes to managing irritable bowel syndrome, the journey goes beyond the reduction of FODMAPs during the fermentation process — the breakdown of the carbohydrates that can make you uncomfortable and gassy. It involves recognising that your gut is compromised and addressing the emotional aspects that come with it. Understanding that IBS sits at the intersection of nourishment, digestion, and your ability to relax and de-stress is crucial. It is about communicating to your gut-brain axis that everything is calm. Learn more about the science behind this in our article The Science of Sourdough Fermentation.

Genetics, the Gut-Brain Axis, and Why Lifestyle Still Matters

IBS is polygenic, which means many small genetic variants add up to influence risk. What is striking in the recent data is how much overlap there is between IBS genes and those linked to anxiety and depression. The same biological pathways that make some people more prone to gut symptoms also shape how they experience mood. The architecture of the gut-brain axis is written into our DNA, and the GWAS work is now showing us, in detail, where the wiring runs.

There are also emerging links to carbohydrate digestion and to genes that influence stool frequency. Some people carry variants in pathways like sucrase-isomaltase that make them more sensitive to certain carbohydrates, which is one reason FODMAP reduction through long fermentation can be so transformative for them. If you have always felt that bread treats you differently from the way it treats your friends, you may well be right.

Here is the part I want you to hold onto. Genetic predisposition shapes the ground you start from, and lifestyle shapes what grows. Epigenetics — the study of how environment switches genes on and off — tells us that what you eat, how you sleep, how much you move, and how often you find moments of calm all influence how your genes are expressed. Sourdough, baked slowly and eaten mindfully, is one of the most practical ways I know to support the biology you were born with.

The Importance of a Calm Mindset in Baking

If you are new to baking sourdough and find yourself getting anxious, remember that anxiety can have the opposite effect on your health. I encourage my students to adopt a simple mantra: “It’s just bread.” This helps manage the stress response, allowing you to enjoy the baking process and letting the microbes in your sourdough starter do their job. These microbes break down sugars, particularly FODMAPs like fructose, which as I mentioned earlier are generally responsible for causing discomfort and gas. For more on this, read our article on Understanding the Gut-Brain Axis.

This calm mindset matters more than it might first appear. Research has shown that the parasympathetic nervous system, particularly through the vagus nerve, regulates gastrointestinal function and gut-brain interactions. When you bake with calm intention — flour on your hands, the rhythm of folding the dough, the smell of fermentation rising in your kitchen — you are doing something deeper than making bread. You are signalling to your nervous system that you are safe. That signal travels down the vagus nerve, into your gut, and across the very pathways the genetics research is now identifying as central to IBS biology. The microbes in your sourdough starter munch on the FODMAPs, and your nervous system gets a moment of tranquility. Both matter.

Tailoring Your Recipes and Taking It Slow

Not all sourdough recipes are suitable for everyone with IBS. Some ingredients included in bread, like seeds or dried fruit, may not be appropriate depending on your specific symptoms. Since IBS is a collection of different symptoms, including gas and varying stool consistency, it is essential to approach recipes with caution. My advice is to take it slow. Start with a small amount, and consider making a recipe and freezing portions to gradually introduce more fibre and diversity into your diet. For more personalised tips, check out my guide on Personalising Sourdough Recipes for IBS.

For your gut to adjust, it might take several weeks of slowly incorporating more fibre. This process helps transform fibre into short-chain fatty acids, calming your digestive system. IBS can be hard. It is debilitating, affecting your social life and emotional wellbeing, and so often people dismiss how difficult this can be. Starting with lower-fibre recipes and gradually increasing the fibre content will help your gut adjust. The fermentation will help predigest your bread, and you can discover the benefits of this process in our article on the Benefits of Long Fermentation.

There is now a genetic angle to this advice as well. People with variants affecting carbohydrate digestion may find that even healthy whole grains feel intolerable at first. Long fermentation — twelve hours, twenty-four hours, sometimes longer — does the work your enzymes are struggling to do. It is bread that has been pre-digested by microbes, and for genetically sensitive guts, that work makes all the difference.

References

1. Staudacher, H. M., & Whelan, K. (2016). Altered gastrointestinal microbiota in irritable bowel syndrome and its modification by diet: probiotics, prebiotics and the low FODMAP diet. Proceedings of the Nutrition Society, 75(3), 306–318. https://pubmed.ncbi.nlm.nih.gov/26908093/

2. Huang, W., Zhang, L., Ma, Y., et al. (2024). Unraveling the genetic susceptibility of irritable bowel syndrome: integrative genome-wide analyses in 845,492 individuals. International Journal of Surgery. https://pmc.ncbi.nlm.nih.gov/articles/PMC11745715/

3. Eijsbouts, C., Zheng, T., Kennedy, N. A., et al. (2021). Genome-wide analysis of 53,400 people with irritable bowel syndrome highlights shared genetic pathways with mood and anxiety disorders. Nature Genetics, 53, 1543–1552. https://www.nature.com/articles/s41588-021-00950-8

4. Alemany-Navarro, M., Diz-de Almeida, S., Cruz, R., et al. (2023). Genome-wide multi-trait analysis of irritable bowel syndrome and related mental conditions identifies 38 new independent variants. Journal of Translational Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10120121/

5. Henström, M., Diekmann, L., Bonfiglio, F., et al. (2018). Functional variants in the sucrase–isomaltase gene associate with increased risk of irritable bowel syndrome. Gut, 67(2), 263–270. https://pmc.ncbi.nlm.nih.gov/articles/PMC5563477/

6. Zheng, T., Eswaran, S., Photenhauer, A. L., et al. (2020). Sucrase–isomaltase 15Phe IBS risk variant in relation to dietary carbohydrates and faecal microbiota composition. Gut, 69(2), 397–398. https://pmc.ncbi.nlm.nih.gov/articles/PMC6839836/

7. Garcia-Etxebarria, K., Bujanda, L., D’Amato, M., et al. (2023). Genetic variants in carbohydrate digestive enzyme and transport genes associated with risk of irritable bowel syndrome. medRxiv. https://pmc.ncbi.nlm.nih.gov/articles/PMC10543038/

8. Bonaz, B., Bazin, T., & Pellissier, S. (2018). The vagus nerve at the interface of the microbiota-gut-brain axis. Frontiers in Neuroscience, 12, 49. https://pubmed.ncbi.nlm.nih.gov/29467611/

9. Laatikainen, R., Koskenpato, J., Hongisto, S. M., et al. (2017). Pilot study: comparison of sourdough wheat bread and yeast-fermented wheat bread in individuals with wheat sensitivity and irritable bowel syndrome. Nutrients, 9(11), 1215. https://pmc.ncbi.nlm.nih.gov/articles/PMC5707687/

10. Boukid, F., Comaposada, J., Ribas-Agustí, A., & Castellari, M. (2023). Enhancing bread’s benefits: investigating the influence of boosted native sourdough on FODMAP modulation and antioxidant potential in wheat bread. Foods, 12(19), 3574. https://pmc.ncbi.nlm.nih.gov/articles/PMC10572427/

11. Ziegler, J. U., Steiner, D., Longin, C. F. H., et al. (2021). FODMAP fingerprinting of bakery products and sourdoughs: quantitative assessment and content reduction through fermentation. Foods, 10(6), 1334. https://pmc.ncbi.nlm.nih.gov/articles/PMC8074121/