Is Sourdough Really Good for You? Here’s What the Science Says

While sourdough might seem like just another type of bread you can make or buy, it actually used to be one of the only options. Until the development of commercial yeasts in the 1800s, sourdough, made with naturally occurring yeasts and lactic acid bacteria, was the main type of leavened bread consumed worldwide.

Sourdough undergoes natural fermentation rather than relying on additives found in baker’s yeast. This means that, compared to other breads, it is easier to digest, has a less significant impact on blood sugar, and is potentially more nutritious.

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

Sourdough also has lower levels of other compounds known to cause gastrointestinal issues, including:

• FODMAPs
• Phytates
• Tannins
• Trypsin inhibitors

This means that sourdough may be easier to digest and result in fewer gastrointestinal symptoms compared to commercially leavened bread.

Study Highlight: A 2023 review of 25 studies showed that people who switched from bread made with baker’s yeast to sourdough bread reported significant improvements in 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 spike in blood sugar levels after eating.

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

For example, the GI for a 30-gram (g) serving of bread made with white wheat flour is 71, while the GI for a 30g serving of sourdough bread is 54.

Anti-nutritional factors found in whole wheat or grain breads, such as phytates, tannins, and trypsin inhibitors, can make it harder to absorb nutrients from food. Phytates, in particular, are able to 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 degrade over 96% of the phytic acid in the dough.

Here’s the nutrition breakdown for a medium-sized, 59-gram slice of sourdough made with enriched white flour:

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

While sourdough contains less gluten than other breads made with wheat flour, it’s not gluten-free and isn’t safe for people with celiac disease or those who are sensitive to gluten-containing foods.

If you’d like 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 with millet, sorghum, teff, quinoa, and buckwheat. 

Note: Gluten-free sourdough will have a different texture than sourdoughs made with wheat flour, as gluten adds a chewy and airy texture to baked goods.

Sourdough is a tangy-tasting bread made with naturally occurring yeasts and lactic acid bacteria. 

Remember:

• Sourdough bread may be easier to digest compared to refined breads made with baker’s yeast.
• It has a less significant impact on blood sugar levels.
• Most sourdough provides a good source of several vitamins and minerals, including B vitamins and selenium. 
• Those who need to avoid or restrict gluten should opt for sourdough made with gluten-free flours.