What Eating Sourdough Bread Does to Your Gut, Blood Sugar, and More

Sourdough undergoes natural fermentation rather than relying on additives found in baker’s yeast. For this reason, it might have more benefits than other types of bread. Here are three ways sourdough can positively impact your body:

The fermentation process used to create sourdough helps break down gluten, a protein found in grains like wheat, barley and rye that resists digestion.

Sourdough also contains lower levels of other compounds known to cause gastrointestinal problems, including:

• FODMAP
• Phytates
• Tannins
• Trypsin inhibitors

This means that sourdough may be easier to digest and cause fewer gastrointestinal symptoms compared to store-bought sourdough bread. A 2023 review of 25 studies showed that people who switched from baker’s yeast to sourdough bread reported significant improvements in their gastrointestinal comfort.

The fermentation process used to make sourdough produces organic acids, such as lactic and acetic acids, which help slow the absorption of starch in the digestive tract. When food is digested slowly, glucose is released more gradually into the bloodstream, preventing a significant rise in blood sugar levels after eating.

This means that compared to other breads, the leaven is weak the glycemic index, a classification system that ranks carbohydrate-rich foods on a scale of 0 to 100 based on their impact on blood sugar levels. The glycemic index estimates how quickly food is digested and absorbed into the bloodstream.

For example, the GI of a 30-gram serving of bread made from white wheat flour is 71, while the glycemic index of a 30-gram serving of sourdough bread is 54.

Antinutritional factors found in whole-wheat or grain breads, such as phytates, tannins, and trypsin inhibitors, can make it harder for your body to absorb nutrients from food. Phytates, in particular, can bind to minerals like magnesium, calcium, and iron, blocking their absorption in the digestive tract.

The fermentation process used to make sourdough breaks down anti-nutritional factors like phytates. In fact, some studies suggest that certain sourdough formulations can break down more than 96% of the phytic acid found in dough.

Here is the nutritional breakdown of a medium-sized 59 gram slice of sourdough made from enriched white flour:

• Calories: 188
• Crabs: 36.5 grams
• Fiber: 1.8 grams
• Protein: 7.67 grams
• Fat: 1.26 grams
• Iron: 2.28 milligrams, or 13% of the Daily Value (DV)
• Copper: 0.088 milligrams, or 10% of the DV
• Folate: 82.6 micrograms, or 21% of the DV
• Thiamine: 0.252 milligrams, or 21% of the DV
• Niacin: 3.17 milligrams, or 20% of the DV
• Riboflavin: 0.218 milligrams, or 17% of the DV
• Manganese: 0.33 milligrams, or 14% of the DV
• Selenium: 17.5 micrograms, or 32% of the DV
• Zinc: 0.619 milligrams, or 6% of the DV

Although sourdough contains less gluten than other breads made from wheat flour, it is not gluten-free and is not a good choice for people with celiac disease or those who are sensitive to foods containing gluten.

If you want to enjoy sourdough but can’t eat gluten, choose a gluten-free sourdough product. Gluten-free sourdough bread is made with gluten-free flours such as those made from millet, sorghum, teff, quinoa and buckwheat.

Gluten-free sourdough will have a different texture than sourdoughs made from wheat flour, because gluten adds a chewy, airy texture to baked goods.