Is Sourdough Bread Really Low in Gluten? Dietitians Explain

Many gluten-sensitive individuals turn to sourdough bread for their fix. However, nutritionists warn that not all sourdough products are created equally as it relates to gluten. Here is what you need to know.

Why Sourdough Bread is Generally Healthier Than Its Counterparts

Sourdough bread burst onto the scene during the COVID-19 pandemic when people found themselves with plenty of time on their hands to babysit those starters. The fact that sourdough bread is seen as nutritionally superior to regular bread was just a bonus.

People with gluten sensitivities also tend to gravitate to this type of bread. However, it is important to remember that while traditionally fermented sourdough products are lower in gluten, they are not usually gluten-free.

Nutritionists explain that sourdough bread is generally healthier when it is made with whole-grain flour. The longer fermentation process, driven by wild yeast and lactic acid bacteria, also sets sourdough apart.

According to Serena Pratt, RDN, a registered dietitian nutritionist and digestive health specialist, “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. With reduced phytic acid, those nutrients become easier to absorb.”

The fermentation process also works to lower the overall gluten content. Because it has a lower glycemic index, sourdough bread is better at supporting steadier blood sugar levels. Antonella Dewell, RDN, registered dietitian nutritionist and IBS specialist, said that this lower glycemic index "can be an advantage for people with insulin resistance or diabetes.”

Pratt cautions that not all sourdough products go through a long enough fermentation process to provide these benefits. She explains that “This is probably the most important thing to understand when evaluating sourdough’s health claims and potential benefits.” Pratt goes on to say that "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.”

As such, individuals with gluten sensitivities need to be careful about eating products that claim to be sourdough but are actually made with commercial yeast and acidifying agents. Dewell notes that "The bread tastes ‘sour’ due to the addition of vinegar, but it’s made with baker’s yeast. These are typically packaged breads found in the grocery aisle of the supermarket.”

How to Choose the Best Sourdough for Health Benefits

Dietitians recommend choosing sourdough without the added baker's yeast for better digestibility and health benefits. The best bet is to look for a simple ingredient list that includes just flour, water, salt, and a starter. Pratt recommends shopping at local bakeries or farmers' markets for authentic fermented sourdough products.

Fermented sourdough will naturally have less gluten. This is because the lactic acid bacteria in the starter serve to break down the gluten proteins, making them smaller and inherently reducing the gluten content in the bread.

Dewell explains that several factors influence the overall gluten content in a sourdough product. For instance, the longer the fermentation period, the fewer gluten proteins are likely to survive. The flour used in the recipe can also influence the amount of gluten. Lower-gluten flours include French T55 flour and pastry flour. Lastly, over-kneading or mixing the dough can boost the gluten profile.

Another factor is that the fermentation process used in authentic sourdough bread also reduces carbohydrates that some people find difficult to digest. Dewell notes that “Interestingly, during the fermentation process, the lactic acid bacteria also break down certain rapidly fermentable carbohydrates (fructans, a FODMAP)." She goes on to explain that "This makes sourdough bread more tolerable to people who are sensitive to fructans, such as people suffering from Irritable Bowel Syndrome (IBS).”

An emerging body of research details that it may be the fructans rather than the gluten that is a problem for some people. This could be the reason why some individuals can tolerate sourdough even though it has some level of gluten.

Limits of Sourdough Bread

Pratt warns that “Sourdough is not gluten-free and is not safe for those with celiac disease. 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.”

This does not mean that you are without options if you need to avoid gluten entirely. Breads made with ingredients such as rice flour, sorghum, and tapioca are the most likely to resemble traditional bread in texture. Other types of sourdough-style bread are also made with specific gluten-free flours. Good choices include Canyon Bakehouse, Arise Bakery, New Grains, BREAD SRSLY, and Zukkee Kitchen.

Registered dietitians also warn that there is a wide range of quality levels among gluten-free breads. People with celiac disease need to be intentional about finding products with a certified gluten-free label.

As for boosting the overall nutrition profile of the bread, Pratt recommends that clients "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.”

If you have celiac disease, a gluten sensitivity or IBS, talk to your doctor or a registered dietitian before making changes to your diet.

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