Does Sourdough Have Less Gliadin? A Detailed Breakdown

November 17, 2025 •

3 min read

According to scientific studies, the fermentation process in sourdough can break down significant portions of gliadin and other gluten proteins. This article investigates the extent to which sourdough has less gliadin and its implications for people with gluten sensitivities.

Quick Summary

The long fermentation process in sourdough, driven by lactic acid bacteria, reduces gliadin content by pre-digesting gluten proteins. This can improve digestibility for some with sensitivities, but it does not eliminate gliadin entirely. Sourdough is not safe for individuals with celiac disease.

Key Points

Gliadin Reduction: The natural fermentation process of traditional sourdough, facilitated by lactic acid bacteria, breaks down a portion of the gliadin proteins present in wheat flour.
Not Gluten-Free: Despite the reduction, wheat-based sourdough bread is not gluten-free and contains significant amounts of gluten, making it unsafe for individuals with celiac disease.
Improved Digestibility: For some people with non-celiac gluten sensitivity (NCGS) or IBS, this partial breakdown of gluten and fructans can make sourdough bread easier to digest.
Fermentation Time Matters: A longer, slower fermentation period, typical of traditional sourdough, results in a greater reduction of gliadin compared to commercial fast-fermented breads.
Verify the Process: Commercially produced sourdough bread may not be fermented traditionally. Check labels or ask bakers about fermentation time to ensure you are getting the real deal.
Listen to Your Body: Tolerance for sourdough varies among individuals with sensitivities. It is recommended to approach it cautiously and always consult a health professional for guidance.
Gluten-Free Options: For those who must avoid gluten entirely, sourdough can be made safely using a gluten-free starter and gluten-free flours.

Understanding Gliadin and Gluten Proteins

Gliadin is a primary protein component of gluten, along with glutenin. While glutenin provides elasticity, gliadin is often linked to celiac disease and non-celiac gluten sensitivity. Gliadin's structure, rich in proline, makes it difficult for the human digestive system to break down, potentially triggering immune responses in sensitive individuals.

The Science of Sourdough Fermentation

Sourdough relies on a natural fermentation process involving lactic acid bacteria (LAB) and wild yeast, unlike commercial yeast. This extended process allows microbes time to modify the dough. Enzymes produced by LAB and wild yeasts, along with activated flour proteases in the acidic environment, break down proteins and carbohydrates.

Protein Degradation: This enzymatic activity is shown to reduce gliadin concentration.
Fructan Reduction: The fermentation also reduces fructans, carbohydrates that can cause digestive issues for those with IBS.

The Truth About Gliadin Levels in Sourdough

Sourdough fermentation reduces gliadin but does not eliminate it. The extent of reduction varies with fermentation time, LAB culture, and flour type. Individuals with non-celiac gluten sensitivity (NCGS) might find this reduction improves tolerance. However, this is not the case for those with celiac disease.

Sourdough vs. Commercial Bread: A Comparative Look


Feature	Sourdough Bread	Commercial Yeast Bread
Leavening Agent	Wild yeast and lactic acid bacteria (LAB) from a starter	Packaged, fast-acting baker's yeast
Fermentation Time	Typically 12-48 hours, often with a long, slow proof	A few hours at most, designed for rapid production
Gliadin Breakdown	Substantial breakdown of gliadin into smaller peptides	Minimal breakdown of gliadin due to short fermentation
Fructan Content	Lower levels due to digestion by LAB	Higher levels, which can trigger digestive issues in some
Glycemic Index	Generally lower, leading to a smaller blood sugar spike	Higher, causing a faster rise in blood sugar
Digestibility	Often easier to digest for those with mild sensitivities	Can cause digestive discomfort in sensitive individuals
Celiac Safety	Not safe for celiac disease patients	Not safe for celiac disease patients

The Celiac Disease Warning

Despite reduced gliadin, wheat-based sourdough is strictly not safe for individuals with celiac disease. Celiac disease is an autoimmune disorder where tiny amounts of gluten cause intestinal damage. Testing confirms wheat sourdough exceeds gluten-free standards (20 ppm). Claims of safety for celiacs are dangerous.

Making Sourdough Work for You

For those with NCGS or other sensitivities, properly fermented sourdough can be beneficial. Ensure you obtain a genuine product, as some commercial loaves are faked with added yeast.

Read the Label: Look for a long fermentation time.
Inquire at Artisan Bakeries: Ask bakers about their fermentation process.
Bake Your Own: Control fermentation time (24+ hours) for maximum breakdown of gliadin and fructans. Resources like The Sourdough School can help: https://www.sourdough.co.uk/.
Consider Gluten-Free Flours: For celiac disease or severe sensitivity, use a gluten-free starter and flours like rice or sorghum.

Conclusion: A Nuanced Answer

Sourdough does have less gliadin due to extended fermentation by lactic acid bacteria. This can improve digestibility for individuals with NCGS by breaking down problematic proteins and fructans. However, gliadin is not eliminated. Wheat-based sourdough remains unsafe for celiac disease patients who must avoid all gluten. For those with milder sensitivities, traditional sourdough can be a more tolerable option, but consult a healthcare professional about dietary changes.

Frequently Asked Questions

No, traditional sourdough bread made with wheat flour is not completely gluten-free. While the long fermentation process reduces gliadin levels, it does not eliminate them entirely. For a truly gluten-free option, sourdough must be made with certified gluten-free flours.

People with non-celiac gluten sensitivity (NCGS) may tolerate sourdough better because the fermentation process partially breaks down gliadin and fructans, which are often triggers for digestive discomfort. This 'pre-digestion' by lactic acid bacteria can make the bread easier to handle for a sensitive digestive system.

No, wheat-based sourdough is not safe for individuals with celiac disease. Even with reduced gliadin content, the remaining gluten is sufficient to trigger an autoimmune response that damages the small intestine. Celiacs must strictly adhere to a gluten-free diet.

If you are not baking it yourself, look for bread from artisan bakeries that list a long fermentation time (12-48 hours) or avoid products that use commercial yeast. Many store-bought loaves labeled "sourdough" are fast-leavened and only contain sourdough flavoring.

Gliadin and glutenin are the two main protein components of gluten. Gliadin contributes to dough's viscosity and is primarily responsible for triggering immune reactions in gluten-sensitive individuals. Glutenin gives the dough its elasticity and strength.

Yes, aside from potential improvements in digestibility, sourdough fermentation can offer other benefits. The process can lower the bread's glycemic index, and the action of lactic acid bacteria can also increase the bioavailability of minerals by breaking down phytic acid.

Fructans are a type of fermentable carbohydrate that can cause digestive issues in people with IBS or other sensitivities. The long fermentation in sourdough bread effectively breaks down these fructans, which is another reason some individuals find it easier to digest.