Does Sourdough Have Gliadin? The Truth About Fermentation and Gluten

November 17, 2025 •

3 min read

While sourdough fermentation can significantly reduce the amount of gluten, and thus gliadin, present in wheat flour, studies confirm it does not eliminate it entirely. This means that for individuals with celiac disease, traditional wheat-based sourdough is still not safe to consume.

Quick Summary

Traditional sourdough bread made with wheat flour contains gliadin, a protein component of gluten. Although the long fermentation process breaks down gliadin, it does not remove it completely, making wheat sourdough unsafe for celiacs.

Key Points

Gliadin is Not Eliminated: Traditional sourdough fermentation reduces gliadin levels but does not remove it completely, making it unsafe for celiacs.
Fermentation Breaks Down Gliadin: Lactic acid bacteria and wild yeast in sourdough starters produce enzymes that hydrolyze gluten proteins, including gliadin.
Celiac Disease vs. Sensitivity: The amount of gliadin left in sourdough can still trigger a reaction in those with celiac disease, but may be tolerable for people with non-celiac gluten sensitivity.
Fructans Play a Role: Sourdough's improved digestibility for some is also due to the breakdown of fructans, carbohydrates that can cause digestive issues.
Choose Certified Gluten-Free: For individuals who must avoid gluten entirely, only sourdough made from certified gluten-free flours is safe.
Fermentation Time is Key: The longer the fermentation process, the more gliadin is broken down. This is why properly fermented sourdough differs from commercial bread.

What is Gliadin and Why Does it Matter?

Gliadin is a protein found in grains like wheat, barley, and rye, and is one of the two primary components of gluten. It contributes to dough's elasticity. For most, gliadin is harmless, but in individuals with celiac disease, it triggers an autoimmune response damaging the small intestine.

The Sourdough Fermentation Process and Gliadin Reduction

Sourdough uses a natural starter with wild yeasts and lactic acid bacteria (LAB) for leavening. This slow fermentation impacts gliadin through:

The Role of Lactic Acid Bacteria

Enzyme Production: LAB produce enzymes that break down gliadin and glutenin into smaller fragments.
Increased Acidity: The acidic environment activates native flour enzymes, aiding protein breakdown.
Gluten Network Alteration: Acidity and enzymes weaken the gluten network, leading to partial protein degradation. This can improve digestibility for those with non-celiac gluten sensitivity (NCGS) or IBS.

The Result: Partial, Not Total, Breakdown

Sourdough fermentation reduces gliadin levels but doesn't eliminate it. Wheat-based sourdough still contains gluten significantly above the 20 ppm 'gluten-free' threshold. Therefore, those with celiac disease must avoid sourdough made with wheat, rye, or barley flour.

The Critical Difference: Celiac Disease vs. Non-Celiac Gluten Sensitivity

Some with gluten sensitivity tolerate sourdough, while celiacs cannot. This is key to understanding gliadin's impact.

Celiac Disease: An autoimmune disorder where gluten, particularly gliadin, causes intestinal damage. Any amount of gliadin is problematic, requiring a strict gluten-free diet.
Non-Celiac Gluten Sensitivity (NCGS): Individuals experience symptoms from gluten without intestinal damage or an autoimmune response. The reduced gliadin and fructan content in sourdough may make it more digestible for some with NCGS, easing symptoms like bloating.

Sourdough's Effect on Fructans

Sourdough fermentation also breaks down fructans, carbohydrates in wheat that can cause digestive issues. This fructan reduction contributes to sourdough's improved digestibility for some.

Sourdough Gliadin vs. Conventional Bread Gliadin: A Comparison


Feature	Traditional Wheat Sourdough	Conventional Commercial Bread
Leavening Agent	Wild yeast and lactic acid bacteria (LAB)	Commercial baker's yeast
Fermentation Time	Typically long, 12-48+ hours	Short, often under 2 hours
Gliadin Breakdown	Significant partial degradation by LAB and flour enzymes	Minimal breakdown due to rapid process
Final Gliadin Content	Lower gliadin concentration, but still above gluten-free threshold	Higher gliadin concentration
Fructan Content	Reduced due to fermentation	Higher, as fermentation time is insufficient to break them down
Safety for Celiacs	Unsafe, as gliadin is not fully eliminated	Unsafe, due to high gliadin content
Potential for Sensitivity	May be better tolerated by some with NCGS or IBS due to reduced gliadin and fructans	More likely to cause digestive discomfort in sensitive individuals

Can Celiacs Still Enjoy Sourdough?

Yes, but only if made with certified gluten-free flour and a gluten-free starter. Gluten-free sourdough uses flours like brown rice, sorghum, or teff. Preventing cross-contamination with separate equipment is crucial.

Conclusion: Gliadin Exists, but Effects Vary

Traditional wheat sourdough contains gliadin, though reduced by fermentation. This reduction isn't enough for individuals with celiac disease, who must avoid gluten. However, the partial breakdown of gliadin and fructans can benefit those with non-celiac gluten sensitivity or IBS, making it easier to digest. The safety depends on the individual's condition and flour used. Consult a medical professional for dietary changes. For more information on celiac disease, visit the National Institutes of Health at https://www.niddk.nih.gov/health-information/digestive-diseases/celiac-disease.

Frequently Asked Questions

No, traditional sourdough bread made from wheat flour is not gluten-free. While the fermentation process breaks down some of the gluten, it does not eliminate it entirely. Food must contain less than 20 ppm of gluten to be considered gluten-free.

No, people with celiac disease should not eat traditional sourdough bread, even if it has been fermented for a long time. The residual gliadin is enough to trigger an autoimmune response and cause intestinal damage.

For those with non-celiac gluten sensitivity, the long fermentation process in sourdough reduces levels of gliadin and fructans. The breakdown of these compounds can make the bread easier to digest and reduce symptoms like bloating.

The lactic acid bacteria and wild yeasts in a sourdough starter create an acidic environment and release enzymes. These enzymes break down the gliadin protein into smaller, less complex pieces, which are easier to digest.

Yes, but it must be made with certified gluten-free flours and a dedicated gluten-free starter. These options use alternative flours like rice, sorghum, or teff to ensure no gliadin is present.

Not always. Some commercial 'sourdough' uses baker's yeast and added flavors, bypassing the long fermentation process that breaks down gliadin. True, long-fermented sourdough is necessary for maximum gliadin reduction.

Gliadin is one of the two main proteins that, when combined with glutenin, form the larger gluten complex. Gliadin is specifically recognized by the immune system in celiac disease.

If you are not making it yourself, it can be difficult to know for sure. Look for products that list a long fermentation time or ask the baker directly. Ingredients should typically include only flour, water, and salt, with no added yeast.