Is Sourdough Bread Better for You?

A listener writes with questions about sourdough.

I use homemade whole-grain sourdough daily. I am convinced it has exceptional health benefits but I can't find any nutritional info on it. It seems to me that it has to have probiotics, for instance.

With so many people stuck at home over the last year, bread baking in general, and sourdough in particular, have seen a big rise in popularity. And I think many people share this listener's conviction that sourdough must be somehow more nutritious than regular bread. But are these beliefs backed up by any science?

What is sourdough?

Sourdough is a traditional method of making bread that's a bit more time- and labor-intensive than modern methods. (Perhaps that's why we assume it must also be better for us.) A lot of bread these days is made with dried baking yeast, which is reanimated by combining it with warm water. When mixed with flour, the yeast start to digest the sugars in the flour, releasing carbon dioxide gas. This gas gets trapped in pockets in the dough and causes the dough to rise.  

Sourdough starter is a living, breathing colony that requires ongoing care.

Sourdough bread also uses micro-organisms to generate the gas that makes bread rise. But in this case, lactobacillus bacteria are doing the heavy lifting. These bacteria, along with some uncultivated (or "wild") yeasts, are naturally present in the flour as well as in the air. To make a sourdough starter, you combine flour and water and let it sit loosely covered for several days in a warm room and let nature do its thing. As the bacteria in the flour start to reproduce, they give off carbon dioxide and lactic acid. Eventually, you end up with a tangy, bubbly mixture with enough oomph to leaven a loaf of bread.  

Sourdough bakers will typically take a cup or two of starter out of the batch and then replace it with fresh flour and water. Unlike a packet of dried yeast, which you can store in the fridge for years before using, a sourdough starter is a living, breathing colony that requires ongoing care. If you don't periodically add more flour, the yeast will run out of food and die. (And this is how people end up hiring sourdough babysitters when they go on extended trips.)

What makes sourdough bread unique?

Bread made with sourdough, as opposed to baking yeast, has a characteristically sour or tangy taste that is one of its chief attractions. The texture of the bread is also usually a little denser, moister, and chewier than yeast-risen bread, which adds to its charms. The lactic acid also acts as a natural preservative, meaning that sourdough breads keep well without added preservatives. 

Because the specific micro-organisms...

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