05/23/2026
The safety of Sourdough bread …
Informative article if you are wondering if all sourdough bread is gluten free, low gluten, etc.
Is Sourdough Actually Lower in Gluten? Registered Dietitians Explain
(TLDR - not low enough for those with celiac disease)
Takeaways:
•Sourdough may be slightly lower in gluten, but the reduction depends on fermentation time and ingredients—and it is never gluten-free unless made with gluten-free flour.
•Long fermentation improves nutrient absorption and may ease digestion by breaking down phytic acid and fructans.
•Many store-bought “sourdough” loaves are not actually fermented, so benefits vary widely based on how the bread is made.
Sourdough is easy to make at home and is often framed as a healthier alternative to white bread. But like most things in nutrition, not all sourdough is created equal—and when it comes to gluten, the baking process matters.
While sourdough loaves can be lower in gluten, they’re still not typically gluten-free. We asked registered dietitians to explain what actually happens to gluten during fermentation, why some people find sourdough easier to digest (and some don’t), and what to choose if you need a truly gluten-free option.
In general, sourdough is a more nutritionally dense bread option, especially when it’s made with whole-grain flour. And what makes it a “healthy” bread is largely due to the fermentation process.
“As wild yeast and bacteria work through the dough, they break down phytic acid, a naturally occurring compound in grains that binds to minerals like iron, zinc, and magnesium,” says Serena Pratt, RDN, a registered dietitian nutritionist and digestive health specialist. “With reduced phytic acid, those nutrients become easier to absorb.” Fermentation also helps lower gluten content (more on that later).1
Additionally, sourdough bread can support steadier blood sugar levels compared to many conventional breads. “Sourdough bread has a lower glycemic index, meaning it doesn’t make your blood sugar rise as quickly as regular bread,” says Antonella Dewell, RDN, registered dietitian nutritionist and IBS specialist. “This can be an advantage for people with insulin resistance or diabetes.”
⭐️Not All Sourdough Is Fermented⭐️
Unfortunately, not all sourdough undergoes a long enough fermentation process to matter—and some brands skip the process entirely.
👉🏻 “This is probably the most important thing to understand when evaluating sourdough's health claims and potential benefits,” says Pratt.
“Authentic sourdough requires a live starter (a culture of wild yeast and bacteria), a slow rise, and enough time for fermentation to actually take place, often 12 to 48 hours or more."
Pratt warns to beware of fake "sourdough" made with commercial yeast and acidifying agents, "without the fermentation that drives the nutritional benefits.” That’s where it gets confusing. “The bread tastes ‘sour’ due to the addition of vinegar, but it's made with baker's yeast,” says Dewell. “These are typically packaged breads found in the grocery aisle of the supermarket.”
For better digestibility and potential health benefits, Pratt and Dewell suggest choosing loaves without added baker’s yeast. Instead, look for simple ingredient lists that include just flour, water, salt, and a sourdough starter—but note that some fermented loaves may not include a starter or a sourdough culture. Dewell likes to pick up Trader Joe’s Pain Pauline, which is fermented and includes only whole-wheat flour, water, and salt. “I always go to a bakery or farmer’s market to buy authentic, fermented sourdough,” says Pratt.
So, where does sourdough stand in terms of its gluten content. Sourdough may have slightly less gluten than regular bread, as long as it’s actually fermented. “During the fermentation process, lactic acid bacteria in the starter culture can break down gluten proteins (mainly gliadin) into smaller molecules (‘peptides’), thus reducing the gluten content of the bread,” says Dewell.
There are several other factors that Dewell says can affect the overall gluten content of sourdough:
• Length of fermentation: The longer the fermentation period, the more time there is for the hydrolysis (breaking down) of the gluten proteins.
• Lower-gluten flours: Higher-gluten flours are often used in traditional bread making. Lower-gluten flours include pastry flour and French T55 flour.
• Dough kneading: Over-mixing or kneading can increase gluten development.
Another bonus, beyond the slightly lower gluten content, is that the fermentation process reduces carbohydrates that can be hard for some people to digest.
“Interestingly, during the fermentation process, the lactic acid bacteria also break down certain rapidly fermentable carbohydrates (fructans, a FODMAP),” says Dewll.“ This makes sourdough bread more tolerable to people who are sensitive to fructans, such as people suffering from Irritable Bowel Syndrome (IBS).”
Gluten may not be the main issue for everyone who experiences stomach distress.
“More and more research is identifying that fructans, not gluten, may be the culprit in self-diagnosed gluten intolerance,” says Dewell. This could explain why some people tolerate sourdough better than other breads, even though it still contains gluten.
Still, that doesn’t make it a safe choice across the board: “Sourdough is not gluten-free and is not safe for those with celiac disease,” says Pratt. “Additionally, most grocery store sourdough hasn't gone through this fermentation process at all. So, the amount of gluten in a sourdough loaf depends on how the bread was made.”
If any amount of gluten is a no for your body, there are plenty of alternatives that skip it without sacrificing texture. “For those who need to avoid gluten entirely, whether due to celiac disease or a confirmed sensitivity, breads made with a blend of rice flour, tapioca, and sorghum tend to have the most bread-like texture,” says Pratt. “Almond flour and cassava flour-based loaves are also widely available and tend to hold together well.”
🌟 Gluten-Free Sourdough 🌟
Dewell adds that some brands are now making sourdough-style bread with gluten-free flours, including BREAD SRSLY, Arise Bakery, Zukkee Kitchen, and New Grains.
As a reminder, gluten-free breads can vary significantly in quality. “For anyone with celiac disease specifically, the label needs to explicitly say ‘certified gluten-free,’ since cross-contamination during manufacturing is a concern, even with inherently gluten-free ingredients,” Pratt says. “I generally encourage clients to look for options that also include some fiber from seeds, psyllium husk, or whole grain gluten-free flours, since many gluten-free breads can be low in fiber.”
Author: Laura Thoman for Real Simple
Source: Arora K, Ameur H, Polo A, Di Cagno R, Rizzello CG, Gobbetti M. Thirty years of knowledge on sourdough fermentation: A systematic review. Trends in Food Science & Technology. 2021;108(1):71-83.
