Eating Sourdough Bread Every Day Has An Unexpected Effect On Your Blood Sugar

You might be limiting foods that raise your blood sugar for any number of reasons. For instance, maybe you're diabetic and unable to effectively process glucose. Or perhaps you haven't been diagnosed with diabetes, but you dislike the way you feel when your blood sugar rises and falls. (It's hard to enjoy a sugar crash when you experience hallmark symptoms like dizziness, sweating, trembling, headache, and confusion.)

Regardless of the reason, if you're trying to keep your blood sugar levels at an even keel, you'll probably want to examine the carbohydrates you've been eating. And what could be a more carbohydrate-loaded staple than bread? When you eat many types of bread, the bread's carbohydrates turn into glucose, which can send your system on a sugary rollercoaster ride.

This doesn't mean that you have to bid bread farewell, though. You just have to choose a type that's blood sugar-friendly, like sourdough bread. Thanks to its unique composition, sourdough bread is among the breads of choice for people who monitor their blood sugars.

Every loaf of sourdough begins with a starter, a mixture made of flour and water that's tended for many days or weeks. During that time, the mixture pulls bacteria from itself and its surroundings, causing it to ferment. As it ferments, it begins to take on a sour smell and frothy appearance. When the starter is ready, it becomes the catalyst that provides leavening for sourdough dough. In fact, the starter is the only leavening agent that's required for sourdough; no baker's yeast is needed to bake an airy, tangy, and slice-ready loaf of sourdough bread.

However, the starter doesn't just give sourdough bread its leavening or flavor. It also makes the bread more easily digestible, and therefore less likely to cause sugar overloads. In fact, sourdough bread is considered a low glycemic index (GI) food. As MedicalNewsToday notes, sourdough bread receives a GI ranking of 54, which is lower than other breads. The Glycemic Index Guide puts the GI of wheat bread at 70, white bread at 75, and gluten-free white bread at 90. By comparison, sourdough is much lower on the GI scale, making it a more practical choice if blood sugar maintenance is your goal.

Sourdough bread's positive effect on blood sugar has been documented in scientific studies, reviews, and experiments. For example, a 2022 review published in Critical Reviews in Food Science and Nutrition concluded that "sourdough is effective in reducing the increment of postprandial glycemia, especially when prepared with whole wheat flour." For context, the American Diabetes Association explains that postprandial glycemia is the phase when blood sugar begins to rise. Accordingly, sourdough bread may be able to tame the quickness of that rise, reducing spikes.

This blood sugar effect has been shown in non-human subjects as well as human ones. A 2021 study in the Journal of Agricultural and Food Chemistry explored the outcomes of different types of sourdough breads (based on their starters and ingredients) in rats. Ultimately, the rats who were fed San Francisco sourdough bread seemed to receive the most blood glucose and insulin response benefits. (Fun fact: San Francisco sourdough was highlighted by Bake Magazine, which noted that the secret to at least one San Francisco bakery's sourdough was its one-of-a-kind "mother starter" that had been used for generations.) With that said, sourdough bread isn't the only low-GI bread. You have other options, like whole rye, sprouted grain, and whole wheat bread.