Reviewed by Brunilda Nazario, MD on March 19, 2021
What Is Sourdough?

What Is Sourdough?


Many breads use baker's yeast to leaven the dough, or make it rise. But sourdough begins with a starter, a fermented mixture of flour and water. When flour and water are mixed together and left to sit, wild yeasts and bacteria from the flour -- as well as from your kitchen and your hands -- start to feed on the natural sugars in the flour.  Usually, the only other ingredients are flour, water, and salt.

What Makes It Unique?

What Makes It Unique?


Sourdough made with white flour has a complex flavor, a crispy crust, and a light, chewy texture. This is thanks to microbes like lactic acid bacteria in the starter.  It also has a longer shelf life than other types of bread. Plus, the microbes give sourdough some unique health benefits and help you absorb nutrients better.

It's Rich In Vitamins and Minerals

It's Rich In Vitamins and Minerals


Sourdough packs a hefty nutritional punch. You may be surprised to learn that a slice of it provides a hefty dose of B vitamins like folate, niacin, thiamin, and riboflavin. Sourdough is also rich in the minerals iron, manganese, and selenium.

Sourdough Is Healthier Than Yeast Bread

Sourdough Is Healthier Than Yeast Bread


If you're comparing nutrients, sourdough made with white flour isn't much different from regular white bread. But because it's fermented, sourdough has some unique health properties. For one thing, your body absorbs more of the minerals in sourdough, like iron and selenium. That's because fermentation breaks down phytic acid, a compound that blocks nutrient absorption.

It’s Easier to Digest

It’s Easier to Digest


Research has shown that people digest sourdough bread more easily than breads made with baker's yeast. Sourdough also helps people feel satisfied faster than baker's yeast breads. The lactic acid in sourdough can help break down gluten. This might make it easier for people with gluten sensitivity to enjoy the bread.

It Can Help with Blood Sugar Control

It Can Help with Blood Sugar Control


One small human study found that people who ate sourdough bread had a significantly lower blood sugar spike after 30 minutes, compared to people who ate bread made with baker's yeast. This could be because sourdough has more resistant starch, which takes longer to digest.

It's Heart-Healthy

It's Heart-Healthy


Sourdough fermentation boosts the number of polyphenols in flour. Polyphenols are plant compounds that may help fight conditions like cancer, heart disease, type 2 diabetes, and Alzheimer's.

Is Sourdough Gluten-Free?

Is Sourdough Gluten-Free?


No, sourdough isn't gluten-free unless it's made with gluten-free flour. But the typical flours used in baking -- like all-purpose flour and bread flour – have gluten. 

Making Your Own Starter

Making Your Own Starter


To make sourdough starter, you'll mix equal parts flour and filtered water in a glass jar and leave it on your counter for a couple of days. Then you'll remove some of it, put it into a new jar, and "feed" it with more flour and water. You'll continue to feed your starter and watch for signs of microbial activity, like bubbling and changes in height, texture, and smell. After a couple of weeks, your starter should be ready to bake with.

When To Toss Your Starter

When To Toss Your Starter


Surprisingly enough, gray, brown, or black liquid on the top of your sourdough starter isn't cause for concern. It's called "hooch," and it means that you need to feed your starter. But you'll definitely want to throw away your starter if you notice mold (which will look unmistakably fuzzy) or bad bacteria (usually seen as a pink or orange tint or streak).

Make It Even Healthier

Make It Even Healthier


To boost the nutrition of your sourdough even more, make or buy a whole-wheat version. You'll get more fiber, B vitamins, and minerals like potassium. You can also try it made with other grains, like rye or spelt. Just keep in mind that the more of these flours in the bread, the denser it will be, with less height and fewer air pockets.

Show Sources


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Foods: "Sourdough-Based Biotechnologies for the Production of Gluten-Free Foods."


Scientific American: "The Science of Sourdough: How Microbes Enabled a Pandemic Pastime."


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Journal of Agricultural and Food Chemistry: "Moderate decrease of pH by sourdough fermentation is sufficient to reduce phytate content of whole wheat flour through endogenous phytase activity."


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USDA FoodData Central: “Sourdough,” “White Bread.”