Can You Eat Sourdough on Low FODMAP? The Complete Guide

January 4, 2026 •

4 min read

According to Monash University, traditionally prepared sourdough made with certain flours is considered low FODMAP. This is welcome news for people following the low FODMAP diet who miss bread, as the fermentation process breaks down the fructans that can trigger IBS symptoms. But what exactly makes some sourdough safe while others are not?

Quick Summary

Traditionally prepared sourdough bread made with wheat or spelt flour undergoes a long fermentation process, reducing its fructan and GOS content to low FODMAP levels. Not all sourdough is created equal; authentic, slow-fermented versions are typically safe, while quick-rise varieties or those with high FODMAP additives may not be.

Key Points

Traditional Sourdough is Low FODMAP: Authentically fermented sourdough bread made with white wheat or spelt flour is low FODMAP due to the breakdown of fructans during the long fermentation process.
Avoid 'Sourfaux' Breads: Many commercial breads labeled 'sourdough' are not traditionally fermented and may contain high FODMAPs. Look for loaves without added baker's yeast or vinegar.
Flour Type Matters: While white wheat and spelt are safe, sourdough made with high FODMAP flours like rye or kamut should be avoided during the elimination phase.
Portion Control is Key: Even low FODMAP sourdough has a recommended serving size (typically two slices). Exceeding this can increase FODMAP intake and trigger symptoms.
Homemade is an Option: Baking your own sourdough allows for complete control over the ingredients and fermentation time, ensuring a truly low FODMAP result.
Check for Certified Products: For guaranteed safety, look for products that are officially certified and lab-tested by organizations like Monash University.

Understanding FODMAPs and Fermentation

FODMAPs are a group of short-chain carbohydrates that are poorly absorbed in the small intestine. For individuals with irritable bowel syndrome (IBS), these can draw excess fluid into the bowel and be rapidly fermented by gut bacteria, causing symptoms like bloating, gas, and abdominal pain. Wheat flour, a common ingredient in bread, is high in fructans, a type of oligosaccharide and a major FODMAP culprit.

Unlike commercially produced bread that uses fast-acting baker's yeast, traditional sourdough relies on a symbiotic culture of wild yeast and lactic acid bacteria (LAB). This culture, known as a sourdough starter, ferments the dough over an extended period, often 12 hours or more. During this slow process, the wild yeast and LAB consume and break down the fructans and other carbohydrates in the flour, which significantly reduces the final FODMAP content of the bread. This makes traditionally prepared sourdough, especially varieties made with white wheat or spelt flour, a viable option on a low FODMAP diet.

How to Choose a Low FODMAP Sourdough

It's crucial to understand that not all bread labeled "sourdough" is created equal. Many commercial options are "sourfaux," using flavorings and rapid fermentation to mimic the taste without achieving the necessary FODMAP reduction.

Prioritize Traditional Fermentation: Look for loaves made with only flour, water, and salt, fermented over a long period. Avoid products with additional baker's yeast or vinegar added for a sour flavor, as these indicate a quick-rise process.
Look for Certified Products: The most reliable way to find low FODMAP sourdough is to look for products certified by Monash University or FODMAP Friendly, as these have been laboratory-tested for their FODMAP content.
Consider the Flour Type: Monash University has tested and approved white wheat sourdough, wholemeal wheat sourdough, and spelt sourdough at specific serving sizes. Spelt is naturally lower in fructans and can be a good option. However, other flours like rye and kamut remain high in FODMAPs even after fermentation and should be avoided.

Can you eat homemade sourdough on low FODMAP?

If you have a home-baked sourdough, it can be low FODMAP, but the process is key. A long, slow fermentation time is what makes the difference. Many home bakers follow a process that involves a long bulk fermentation and then a cold proof in the refrigerator for 8 to 12 hours or more. This extended time allows the sourdough culture to thoroughly break down the FODMAPs in the flour. The type of flour used also matters significantly, with white wheat or spelt being the safest choices for a low FODMAP outcome.

Low FODMAP Sourdough Comparison Table


Feature	Traditional Sourdough (Low FODMAP)	Commercial "Sourfaux" Bread	Standard Yeasted Bread
Leavening Agent	Wild yeast and lactic acid bacteria (natural starter)	Combination of starter, commercial yeast, and flavorings	Commercial baker's yeast
Fermentation Time	Long, slow process (12+ hours)	Short, rapid process	Short, rapid process
FODMAP Content	Significantly reduced fructans and GOS	Often high in fructans	High in fructans
Best for IBS	Yes, if traditionally made and consumed within recommended serving sizes	No, likely to cause symptoms	No, likely to cause symptoms
Taste	Complex, tangy, and rich flavor	Often uses additives for a mild, sour taste	Milder, less complex flavor

Potential Pitfalls: What to Watch Out For

Even with a traditionally made sourdough, some factors can increase the FODMAP content.

Added Sweeteners: Some bakeries add sweeteners like honey or high fructose corn syrup to their bread, which are high in FODMAPs. Always check the ingredient list for hidden sugars.
Portion Size: While low FODMAP, sourdough is not FODMAP-free. Monash University has specific serving size recommendations (e.g., two slices of white wheat or spelt sourdough). Overeating can push you over your tolerance threshold and trigger symptoms.
Other High FODMAP Ingredients: Be aware of other potential high FODMAP additions, such as high FODMAP flours (like rye or kamut) or seeds (e.g., cashews).

The Role of Fermentation in Digestibility

The benefits of traditional sourdough fermentation extend beyond just lowering the FODMAP content. The long process helps to pre-digest components of the grain, which may improve overall digestibility for some individuals. The lactic acid bacteria also produce organic acids and bioactive compounds that may support gut health. This improved digestibility, combined with the reduction of fructans, is why many people with IBS find they can tolerate sourdough bread when they can't tolerate other wheat products.

Conclusion

Yes, you can eat sourdough on low FODMAP, but it's crucial to be selective. Choosing a traditionally fermented loaf made with white wheat or spelt flour is the best approach. By understanding the fermentation process and checking for hidden high FODMAP ingredients, individuals with IBS can enjoy this tasty and gut-friendly bread in moderation. The key lies in finding genuine sourdough and respecting the recommended serving sizes. Always consult with a dietitian to determine your personal tolerance, as individual reactions to food can vary significantly. For more comprehensive nutritional information, consider exploring the official Monash University Low FODMAP app for the latest tested foods and serving sizes.

Sourdough on Low FODMAP: A Quick Guide

Here’s a concise summary of the key points for incorporating sourdough into a low FODMAP diet:

Look for real sourdough: Seek out traditionally fermented loaves and avoid 'sourfaux' products that use commercial yeast.
Check the ingredients: Ensure the list is short and free of high FODMAP sweeteners or flavorings like vinegar.
Choose the right flour: White wheat and spelt sourdoughs are low FODMAP when prepared correctly.
Mind your portion size: Stick to the recommended serving size (e.g., two slices) to avoid exceeding your FODMAP tolerance.
Consider homemade: Making your own sourdough guarantees a long, traditional fermentation process that maximizes FODMAP reduction.
Consult a professional: If you're unsure, work with a dietitian to test your personal tolerance to sourdough.
Prioritize slow-rise: A slower fermentation time is a key indicator of a lower FODMAP content, as it gives the microbes more time to break down the problematic fructans.

Frequently Asked Questions

Authentic sourdough bread is made using a long fermentation process with a natural starter of wild yeast and bacteria. These microbes break down the fructans and other FODMAPs in the flour. In contrast, many commercial breads use a faster process with added yeast, which doesn't allow enough time for this breakdown to occur.

Yes, Monash University has certified white wheat sourdough as low FODMAP at a serving size of up to two slices (around 109g). The extended fermentation of traditional sourdough significantly reduces the fructan content.

Yes, traditionally made spelt sourdough is low FODMAP. Spelt flour is naturally lower in fructans, and the fermentation process further reduces the FODMAP content. Always check the Monash app for the latest serving sizes.

'Sourfaux' refers to commercial breads that use a quick process with commercial yeast, flavorings like vinegar, and minimal fermentation to imitate the taste of sourdough. To avoid it, check the ingredient list for added yeast or flavorings and look for traditionally made loaves.

Rye sourdough is generally high in FODMAPs and should be avoided during the elimination phase. While fermentation reduces some fructans, it's not enough to make it low FODMAP, unlike white wheat or spelt.

Not necessarily. A gluten-free sourdough is only low FODMAP if it is made with low FODMAP flours, like brown rice or sorghum, and undergoes a proper fermentation. Always check the ingredient list for high FODMAP additions.

Yes, always check the ingredient list. Honey and high fructose corn syrup are high FODMAP sweeteners that may be added to commercial breads, negating the benefits of fermentation. Look for sourdoughs made only with flour, water, and salt.

Yes. The length of the fermentation is critical for reducing FODMAPs. Shorter fermentation times, often seen in quick-rise commercial products, don't allow sufficient time for the microbes to break down enough fructans.

Besides checking ingredients for commercial yeast, look for loaves sold in the fresh bakery section. You can also ask the baker about their process. Some artisanal products may specify a long fermentation time on the label.