Sourdough Bread? Nutrition & Fermentation Benefits

Using whole-grain flour makes sourdough bread, in particular, a healthier choice. The fermentation process is mainly responsible for making it a "healthy" bread.

Phytic acid is a naturally occurring compound in grains that binds to minerals like iron, zinc, and magnesium. As the wild yeast and bacteria work their way through the dough, they break it down, according to Serena Pratt, RDN, a registered dietitian nutritionist and digestive health specialist. "The nutrients are better absorbed when the phytic acid content is lower." As we'll see in a bit, fermentation is another tool for reducing gluten levels. 1

In comparison to many processed breads, sourdough bread can help keep blood sugar levels stable. Expert in irritable bowel syndrome (IBS) and registered dietitian nutritionist Antonella Dewell says that sourdough bread is better for you than regular bread because it has a lower glycemic index. "People who are diabetic or have insulin resistance may benefit from this."

The fermentation process isn't necessary for all sourdough, and some brands even skip it altogether. “This is probably the most important thing to understand when evaluating sourdough’s health claims and potential benefits," says Pratt. "For homemade sourdough, you need three things: a culture of wild yeasts and bacteria called a live starter, a slow rise, and plenty of time for fermentation to happen—usually twelve to forty-eight hours or more."

"Without the fermentation that drives the nutritional benefits," Pratt says, so be wary of "sourdough" that uses commercial yeast and acidifying agents. It becomes complicated at that point. The use of vinegar gives the bread a "sour" flavour, but according to Dewell, the secret ingredient is baker's yeast. "You can usually find these breads in their packaging in the grocery section of the store."

Pratt and Dewell recommend avoiding breads that have added baker's yeast for improved digestibility and possible health advantages. Try to find fermented breads that don't have a lot of ingredients, like a sourdough starter or a starter and water, but instead stick with the basics like flour, water, salt, and a starter. Pain Pauline, a fermented bread made with only whole-wheat flour, water, and salt, is a favourite of Dewell's from Trader Joe's. "Whenever I want to buy real, fermented sourdough, I always visit a bakery or a farmer's market," Pratt says.

Now we need to know how much gluten sourdough contains. If sourdough is fermented properly, it may contain slightly less gluten than white bread. Gluten proteins, primarily gliadin, can be broken down into smaller molecules called 'peptides' by the lactic acid bacteria in the starter culture during fermentation. This process reduces the gluten content of the bread, according to Dewell.

In addition to a slightly reduced gluten content, another perk is that fermentation lowers carbs, which some people have trouble digesting. The lactic acid bacteria also degrade fructans, a FODMAP, and other quickly fermentable carbs, according to Dewell, "interestingly", during fermentation. "For those with fructan sensitivities, like those with Irritable Bowel Syndrome (IBS), this makes sourdough bread more bearable."