Is Sourdough Bread Good for You?

Some claim it's healthier than conventional bread. We checked out the research.

a loaf of sourdough bread on a cutting board Photo: Getty Images

Sourdough bread has been around since the days of ancient Egypt, but even if you’ve never paid too much attention to it before, chances are sourdough is on your radar now. The tangy-tasting baked good achieved a near cult-like status at the beginning of the pandemic that continues to this day. A current search of #sourdoughbread on Instagram yields 2.3 million photos of users showing off their baguettes, boules, starters, and kitchen experiments.

Along with its, ahem, rise in popularity, sourdough has gotten a reputation for being so much more than just another white bread. It’s been described as magical, gorgeous, and, of course, delicious. But some people claim that sourdough is packed with probiotics, easier to digest, and better for your blood sugar, and is otherwise generally healthier for you than conventional white bread. What does the science show? We dug into the research and consulted experts to find out.

How Is Sourdough Made?

Until relatively recently, sourdough bread was the only leavened bread that existed. “Back in the day, there was no little packet of yeast one could use,” says Robert Hutkins, PhD, professor of food science at the University of Nebraska-Lincoln and an expert on fermented foods. (That product actually came into being during World War II, when Fleishmann’s developed and packaged active dry yeast.)

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To make sourdough, you need a starter—a mixture of flour and water that’s been left to ferment for several days. The wild yeasts and bacteria in the flour and the environment feed on the flour and water, multiplying and creating a mixture that bubbles and grows.

The bacteria and yeast produce acids and other compounds that make the bread rise and give sourdough bread its characteristic flavor. The longer the fermentation time, the stronger this sour flavor becomes, says Willow Jarosh, a culinary registered dietitian in private practice in New York City and an avid sourdough baker. The acids that are produced also kill any bad bacteria, which is why a sourdough starter can last many, many years if properly cared for.

Sourdough's Health Benefits

Sourdough’s long fermentation and rising time leads to changes in the bread that don’t occur in conventional yeast-leavened breads. These changes may have health benefits for some people, especially those with certain digestive issues.

The microbes in the starter break down some of the gluten, the main protein in wheat flour, so sourdough is somewhat lower in gluten than other breads. “It’s not reduced enough to allow gluten allergic or celiac patients to consume bread, but possibly enough for people with modest gluten sensitivities,” Hutkins says.

Sourdough may also be easier to digest for those who suffer from irritable bowel syndrome, or general gas, bloating, and other digestive problems after eating certain types of carbohydrates, often referred to as FODMAPs. “Traditional wheat bread leavened with baker’s yeast contains high levels of fructans, which can be a symptom trigger in many people with IBS,” says Kate Scarlata, a registered dietitian specializing in digestive health, and the author of "The Low-FODMAP Diet Step by Step" (De Capo Lifelong Books, 2017). “The process of slow leavening bread via sourdough culture reduces its fructan content by as much as a 92 percent,” she says. 

The bacteria and yeast also produce acetic and lactic acids, which slow your digestion of the bread’s carbohydrates. Therefore sourdough has a lower glycemic index—a measure of how much your blood sugar increases after eating a food—than other breads. Whether that has a significant effect for people with diabetes or other blood sugar issues is debatable. “Bread is rarely eaten alone, but rather with something like cheese, meat, or nut butters that will change the overall glycemic index of the meal,” Jarosh says. 

But don’t count on sourdough bread to get gut-friendly probiotics. “Although it’s a fermented food like yogurt or kimchi, the probiotic bacteria in sourdough bread is killed during baking, so it doesn’t provide healthy bacteria to your system,” says Jarosh.

Sourdough Nutrition

Like conventional bread, sourdough can be made with different types of flours. The nutrition profile of the loaf depends on which type is used, with white flours having less fiber and nutrients and whole-grain flours having more nutrition, mainly fiber and B vitamins.

Overall, the nutrition facts of white sourdough bread and white conventional bread are fairly similar.

• 1-ounce slice of sourdough white bread contains 77 calories, 3 grams protein, 15 g carbohydrate, and 1 g fiber.

• 1-ounce slice of white bread contains 75 calories, 2.5 grams protein, 14 g carbohydrate, and 1 g fiber.

You may get more nutrients out of a slice of sourdough, though. “Some flours contain phytic acid, which is considered an ‘anti-nutrient’ due to its ability to bind important minerals, like zinc, iron, and calcium,” Hutkins says. “Sourdough microbes degrade the phytic acid, enhancing the nutritional quality of the bread.”

If you have the desire and opportunity to make sourdough at home, using a whole-grain flour or a combination of white and whole grain in your recipe will increase the fiber and nutrients a bit. But Jarosh suggests playing around with the flour combination that creates the flavor and texture you like best. “You can always top the bread with foods that contain fiber and nutrients,” she says. “I personally prefer to use a combination of white flour because it creates a springier texture and some whole-wheat flour, for the nutty flavor.”

Packaged vs. Homemade Sourdough

All these benefits apply only to real sourdough, made in this traditional way, however—not to many commercial sourdough breads. “Many commercial bakeries have abandoned the traditional sourdough process due to long fermentation times,” says Hutkins. “Instead, they add an acidic agent, like vinegar, for sour flavor, and speed up the process by using yeast to leaven the bread.” This doesn’t impart the benefits that sourdough made the slow-leavened way does because the microbes don’t have time to work their magic. “If you want authentic sourdough bread, you’ll have to do some consumer research and shop around a bit, or make it yourself," he says.

How can you tell the difference? Check the ingredients list. Look for sourdough culture or starter and no yeast, says Scarlata. Or ask the bakery whether the bread is slow leavened for at least 8 to 24 hours.

Another distinction: Most packaged breads contain preservatives, but true sourdough naturally has a longer shelf life. That’s due in large part to the acids acting as antifungal agents, Hutkins says. “In addition, sourdough is resistant to staling, which often is the reason why people toss otherwise healthy bread into the trash.”

Stephanie Clarke RD

Stephanie Clarke

Stephanie Clarke, RD, is the founder of C&J Nutrition, a nutrition consulting, communications, and workplace wellness company. She lives in the Washington, D.C., suburbs of Maryland with her husband and two young daughters.