The rise of at-home bread baking during the pandemic may have seemed like sourdough’s peak popularity, but demand keeps growing. Supermarket brands, restaurants and bakeries are embracing sourdough well beyond bread, with everything from bagels and pizza to doughnuts, crackers and pastries. Some are also making claims that these products are easier to digest, help control blood sugar or support gut health.
Is sourdough actually healthier than regular bread, though? “I don’t think we have a lot of scientific evidence to say that it’s inherently healthier,” said Kate Scarlata, a Massachusetts-based registered dietitian specializing in digestive health who co-authored a review on dietary carbohydrates and irritable bowel syndrome (IBS).
Still, sourdough fermentation changes bread in ways that could have health benefits. Unlike bread leavened with baker’s yeast alone, sourdough is made with a starter containing yeasts and lactic acid bacteria. Fermentation gives the bread its characteristic tangy flavor and changes its chemical makeup, breaking down some carbohydrates and proteins.
But the extent of those changes depends on how the bread is made, and it’s unclear whether they translate into meaningful health benefits, according to Michael Gänzle, a food microbiologist and professor at the University of Alberta who co-authored a 2023 review on the topic.
The potential benefits of sourdough
That said, sourdough might have a few advantages for some people. The sourdough fermentation process can reduce FODMAPs, a group of poorly absorbed carbohydrates that can contribute to gastrointestinal symptoms (such as stomach pain, bloating or diarrhea) in those with IBS. “The yeast and the bacteria that are innate to the sourdough fermentation process will consume some of those carbohydrates, and break them down,” Scarlata explained.
However, fewer FODMAPs doesn’t necessarily mean people feel better. In a small 2017 clinical trial, long-fermented sourdough wheat bread contained 74 percent fewer fructans (a type of FODMAP) than yeast-fermented bread, but participants with IBS reported no significant difference in gastrointestinal symptoms.
Another trial compared traditional rye sourdough with a rye sourdough specifically designed to be low in FODMAPs, and found that the modified bread modestly reduced some digestive complaints. However, overall IBS severity and quality of life not differ significantly between the two breads.
The degree of FODMAP reduction can vary depending on fermentation time, the grain used, the specific microbes involved and the proportion of flour fermented.
Those potential digestive perks may not matter much for people without IBS or related symptoms. “There doesn’t really seem to be any health benefit from the FODMAP perspective of sourdough bread for the general person out there,” Scarlata said.
Similarly, sourdough fermentation can partially break down gluten proteins. Some people who report gluten sensitivity may tolerate sourdough better, but it’s unclear whether that reflects changes to the bread or expectations about how it will affect them, Gänzle said. (This doesn’t make wheat sourdough safe to eat for people with celiac disease or a wheat allergy.)
Some sourdough advocates also claim that it’s “gut healthy” because fermentation gives the bread probiotic or prebiotic benefits, but baked sourdough doesn’t contain live probiotics. “Even if you put a probiotic strain in to ferment it, we’re killing it when we’re baking it. And probiotics are alive,” Scarlata explained. Sourdough may contain prebiotics, substances that feed beneficial gut microbes, but that depends on the flour and other ingredients used in the bread, Scarlata said.
There’s also evidence that sourdough fermentation can make certain minerals more available for absorption. Phytate is a compound that binds to minerals in wheat, including iron, zinc, calcium and magnesium. The sourdough fermentation process helps to break down phytate, potentially allowing the body to absorb more of those minerals. However, even if sourdough increases mineral availability, it’s unclear whether this meaningfully helps people meet their daily needs, Gänzle said.
Finally, what about the blood-sugar claim? Some studies suggest sourdough produces a smaller rise in blood sugar after a meal than regular bread, but findings are inconsistent and don’t yet demonstrate lasting improvements in blood-sugar control.
So, is sourdough actually healthier?
In the end, the sourdough label alone doesn’t make a bread or baked good more nutritious. Most people shouldn’t feel they need to buy sourdough because of claims that it offers distinct perks that regular bread doesn’t. That’s especially relevant since long-fermented sourdough can be more expensive or harder to come by, depending on where you live, Gänzle said.
Generally speaking, longer fermentation allows more time for sourdough’s microbes to break down compounds such as FODMAPs and phytate, Gänzle explained. By allowing the bread to ferment over several hours, “you’re giving it the opportunity to interact with that bevy of yeast and bacteria to really do their magic,” Scarlata explained. Still, there’s no set fermentation time that guarantees a low-FODMAP bread or health benefit.
Fermentation time isn’t usually listed on a package. If you’re buying locally, Scarlata recommends talking to the baker about their process and asking if a product is long-fermented. While the addition of baker’s yeast on an ingredient list can sometimes signal a shorter fermentation cycle, it isn’t a reason to rule out a loaf. Gänzle said home bakers, especially, can consider combining sourdough fermentation with baker’s yeast to help make sure the dough rises.
With non-bread products, such as doughnuts, pizza and crackers, the effect of sourdough fermentation likewise depends on how they’re made. Otherwise, when it comes to nutrition, a sourdough doughnut is still a doughnut, and a sourdough bagel is still a bagel.
If you have IBS, a FODMAP sensitivity or non-celiac gluten sensitivity and want to try sourdough for its potential digestive benefits, pay attention to how your body handles it. Different breads and products may affect you differently depending on how they’re made. As Gänzle put it, “If it works for you and you like it, continue eating it.”
Ultimately, for overall health and more nutritional bang-for-your-buck, the more important move in the bread aisle is choosing a whole-grain product, Gänzle said. Whole grains provide dietary fiber, which promotes digestive health and helps reduce the risk of chronic disease. Around 95 percent of Americans don’t get enough fiber, Scarlata said.
Many sourdough products are made with refined grains, but there are sourdough breads made with whole grains, she added. If you do opt for non-whole-grain sourdough, you can get fiber elsewhere in your meal or snack. For example, add veggies to your sourdough sandwich or sprouts to your avocado toast. “It’s not like we can only get fiber from bread, but you’d want to pair it with things that would provide that nutrient that we’re all too low in,” Scarlata said.
Of course, if you want more control over your sourdough’s ingredients and fermentation, you can always make your own. Otherwise, enjoy sourdough without feeling obligated to choose it for its potential health benefits.
For Gänzle, it comes down to nutrition and preference: “Eat whole grain bread, and if you like the sourdough bread better, then eat it because it tastes better.”
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