Sourdough bread is one of my favorite types of bread.

Not only do I find it tastier than conventional bread, but it’s also arguably more nutritious. Sourdough bread is also less likely to spike your blood sugar than conventional bread, and many of my clients find it easier to digest.

In this article, I review the latest science behind sourdough bread, as well as the many reasons it could be a worthy addition to your diet.

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Sourdough is one of the oldest forms of grain fermentation.

Experts believe it originated in ancient Egypt around 1500 B.C. and remained the main method of leavening bread until baker’s yeast replaced it a few hundred years ago (1).

Breads can be categorized as either leavened or unleavened.

Leavened breads have a dough that rises during the bread-making process. This is caused by the gas that’s released as the grain in the dough begins to ferment (2).

Most leavened breads use commercial baker’s yeast to help the dough rise.

On the other hand, unleavened breads, such as flatbreads like tortillas and roti, do not rise.

Sourdough bread is a leavened bread. However, rather than using baker’s yeast to rise, it’s leavened by “wild yeast” and lactic acid bacteria that are naturally present in flour (3).

Wild yeast is more resistant to acidic conditions than baker’s yeast, which allows it to work together with lactic acid bacteria to help the dough rise (4, 5).

Lactic acid bacteria are also naturally found in several other fermented foots, including yogurt, kefir, pickles, sauerkraut, and kimchi (6).

The mix of wild yeast, lactic acid bacteria, flour, and water used to make sourdough bread is called a starter. During the bread-making process, the starter ferments the sugars in the dough, helping the bread rise and acquire its characteristic flavor (5, 7).

Sourdough bread also naturally contains varying levels of acetic acid bacteria, a group of bacteria that give sourdough bread its particular vinegar-like aroma.

Starters with high levels of acetic acid bacteria also take longer to ferment and rise, giving sourdough bread its characteristic texture (5, 8).

The yeast naturally found in sourdough bread is also thought to increase the bread’s nutrient content and make it easier for your body to digest than bread that’s made using baker’s yeast (4, 5).

Despite its ancient roots, sourdough bread making remains popular to this day — maybe even more so as a result of the surge in interest in home baking that has occurred during COVID-19 pandemic lockdowns throughout the world (9).

Keep in mind that not all store-bought sourdough breads are made using the traditional sourdough method, and this may reduce their health benefits.

Buying sourdough bread from an artisan baker or a farmers market increases the likelihood of it being “true” sourdough bread (2).

Summary

Sourdough uses an ancient form of bread leavening. It relies on a mix of wild yeast and lactic acid bacteria that are naturally present in flour, rather than baker’s yeast, to leaven the dough.

Sourdough’s nutrition profile is similar to those of most other breads and will be influenced by the type of flour that is used to make it — for instance, whether it’s made from whole or refined grains.

On average, one medium slice of sourdough bread made with white flour and weighing approximately 2 ounces (59 grams) contains (10):

  • Calories: 188
  • Carbs: 37 grams
  • Fiber: 2 grams
  • Protein: 8 grams
  • Fat: 1 gram
  • Selenium: 32% of the Daily Value (DV)
  • Folate: 21% of the DV
  • Thiamine: 21% of the DV
  • Niacin: 20% of the DV
  • Riboflavin: 17% of the DV
  • Manganese: 15% of the DV
  • Iron: 13% of the DV
  • Copper: 10% of the DV

Aside from its nutrient content, sourdough has some special properties that allow it to surpass the benefits of most other types of bread. I’ll be discussing these in the following chapters.

Summary

Sourdough’s basic nutrition profile resembles those of other breads and depends on which type of flour is used to make it. Sourdough also has a few special properties that make it more nutritious.

Although sourdough bread is often made from the same flour as other types of bread, the fermentation process used to make it improves its nutrition profile in several ways.

For one thing, whole grain breads contain a good amount of minerals, including potassium, phosphate, magnesium, and zinc (11).

However, your body’s ability to absorb these minerals is limited by the presence of phytic acid, also commonly called phytate.

Phytate is naturally found in several plant-based foods, including grains, and is often referred to as an antinutrient because it binds to minerals, making them more difficult for your body to absorb (11).

The lactic acid bacteria found in sourdough bread lower the bread’s pH, which helps deactivate phytate. Because of this, sourdough bread tends to contain less phytate than other types of bread (11, 12).

Research suggests that sourdough fermentation could reduce the phytate content of bread by more than 70%, with the lowest levels found in breads made from doughs with pH levels between 4.3 and 4.6 and fermented at 77°F (25°C) (13).

What’s more, the dough’s low pH, combined with the lactic acid bacteria it contains, tends to increase the nutrient and antioxidant content of sourdough bread (12, 13).

Finally, sourdough’s longer fermentation time helps improve the aroma, flavor, and texture of whole grain bread. So if you aren’t typically a fan of whole grain bread, a whole grain sourdough bread may be the perfect way to include whole grains in your diet (13).

Summary

Sourdough bread contains higher levels of vitamins, minerals, and antioxidants than other breads. It also contains lower levels of phytate and therefore allows your body to absorb the nutrients it contains more easily than those in regular bread.

Sourdough bread is often easier to digest than bread that’s been fermented with brewer’s yeast.

The lactic acid bacteria and wild yeast present during sourdough fermentation help neutralize the antinutrients naturally found in grains, which helps your body digest foods made from these grains more easily (12, 13, 14, 15).

Sourdough fermentation may also produce prebiotics, a type of indigestible fiber that feeds the beneficial bacteria in your gut, in turn easing digestion and improving your gut health (14, 16).

What’s more, the sourdough fermentation process also helps break down large compounds found in grains, such as gluten proteins, ultimately making them easier for your body to digest (13).

Gluten is a type of protein found in certain grains. It can cause digestive issues in people who are sensitive or allergic to it (11).

Gluten tolerance varies from person to person. Some people have no noticeable issues digesting gluten, whereas in others it can cause stomach pain, bloating, diarrhea, or constipation (17).

Sourdough bread’s lower gluten content may make it easier to tolerate for people who are sensitive to gluten.

This makes gluten-free sourdough bread an interesting option for people with gluten-related disorders.

However, keep in mind that sourdough fermentation does not degrade gluten completely. People with celiac disease or non-celiac gluten sensitivity should avoid sourdough bread containing wheat, barley, or rye.

Summary

Sourdough bread contains lower amounts of gluten, lower levels of antinutrients, and more prebiotics — all of which may help improve your digestion.

Sourdough bread may have a better effect on blood sugar and insulin levels than other types of bread, though scientists don’t fully understand the reason for this.

Researchers believe that sourdough fermentation may change the structure of carb molecules. This reduces the bread’s glycemic index (GI) and slows down the speed at which sugars enter the bloodstream (13, 14).

However, several factors can affect the GI response, and more research is needed on how sourdough affects it (18).

The GI is a measure of how a food affects blood sugar. Foods with a lower GI are less likely to produce a spike in blood sugar levels.

In addition, the lactic acid bacteria found in the dough produce acids during fermentation. Some researchers believe these acids may help prevent a spike in blood sugar (13, 19).

The sourdough fermentation process is often used to make rye breads because rye does not contain enough gluten for baker’s yeast to work effectively.

One study showed that participants who consumed rye bread had a lower spike in insulin levels than those who ate the same amount of conventional wheat bread (20).

In addition, several other studies have compared participants’ blood sugar increases after eating sourdough bread and bread fermented with baker’s yeast.

Generally, participants who ate the sourdough bread had lower blood sugar and insulin levels than those who ate the breads fermented with baker’s yeast (3, 21, 22, 23).

Summary

Sourdough fermentation produces changes in the bread that may help control blood sugar better than bread made using traditional baker’s yeast.

You can make fresh sourdough bread at home from three simple ingredients: water, flour, and salt.

Here is a quick overview of the steps required:

  1. Make a sourdough starter a few days beforehand. You can find many simple recipes online. Creating an initial starter takes less than 5 minutes.
  2. Feed your starter daily and let it grow for a few days. You will use part of this starter to make the bread and save the rest for future use.
  3. On the day you want to make your bread, mix part of your starter with flour and water and allow this mixture to rest for a few hours. Then add salt.
  4. Fold the dough a few times before letting it rest again for 10–30 minutes. Repeat the folding and resting steps a few times, until the dough becomes smooth and stretchy.
  5. On the final rest, let the dough rise at room temperature until it grows to about 1.5 times its original volume.
  6. Shape your bread loaf and bake it in a Dutch oven.
  7. Allow the bread to cool on a rack for 2–3 hours before slicing it.

Keep in mind that making your sourdough starter will take 3–5 days. Do not rush this process, as the quality of your starter is what will give your dough a good flavor and help it rise.

Also, note that you will use only part of the starter to make the bread. You can save the rest for future use as long as you refrigerate it and “feed” it at least once a week.

When you’re ready to make another loaf, simply take your starter out of the fridge 1–3 days ahead of time and feed it once a day until it strengthens again.

Summary

Follow the steps above to make your first loaf of bread. An online search will reveal many recipes for sourdough starter and bread that you can follow.

Sourdough bread is a great alternative to conventional bread.

It’s richer in nutrients, less likely to spike your blood sugar, and generally easier to digest.

Just remember that sourdough fermentation doesn’t degrade gluten completely. So if you have celiac disease or non-celiac gluten sensitivity, it’s best to avoid sourdough bread made from wheat, barley, or rye, all of which contain gluten.

Many people report that sourdough bread has a better aroma, flavor, and texture than bread made using baker’s yeast. All things considered, you may want to give sourdough bread a try.

You can make sourdough bread from virtually any type of flour. For the most benefits, choose a sourdough bread made from whole grains over one made from refined grains whenever possible.