Traditional sourdough bread has been around for thousands of years, but its potential health benefits have only recently been more widely explored. Researchers are learning that the sourdough fermentation process may improve digestion, promote better blood sugar control, and enhance nutrient availability.
1. Easier to Digest
Fermentation breaks down some of the nutrients in bread flour, which can make sourdough easier to digest. It reduces levels of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) by up to 75 percent. FODMAPs are carbohydrates that are not easily digested and may trigger gastrointestinal symptoms like bloating, constipation, and diarrhea in individuals with gastrointestinal sensitivity or when consumed in excess of 20 g per day.
“Sourdough bread is often easier to tolerate for people with digestive conditions like irritable bowel syndrome or nonceliac gluten sensitivity,” says Avery Zenker, RD, a nutritional counselor for MyCrohnsAndColitisTeam who is based in Ontario, Canada.
Fermentation also reduces the gluten content of the bread, which can make sourdough a better option for people with a gluten sensitivity. However, while fermentation lowers gluten levels, it doesn’t eliminate it entirely. For that reason, people with celiac disease should only choose sourdough bread made with gluten‑free flour.
In addition, fermentation with lactic acid bacteria reduces the phytic acid content of sourdough bread, which can further improve digestibility. High levels of phytic acid can interfere with digestive enzymes that help break down food and may contribute to abdominal discomfort or increased gas. By lowering phytic acid, traditional sourdough fermentation makes the bread gentler on the digestive system.
2. May Be Gentler on Blood Sugar
The sourdough fermentation process may result in bread with a lower glycemic index than other bread, which could be beneficial for blood sugar control. The glycemic index evaluates how quickly a food causes blood sugar to rise.
“Authentic sourdough tends to cause a slower blood sugar response than white bread, leading to more stable blood sugar levels,” Zenker says, adding that this is particularly notable for individuals with insulin resistance, such people with diabetes and metabolic syndrome.
However, the overall evidence is mixed, and results vary across studies. Some report little to no difference in glycemic response than with other bread, likely due to inconsistencies in starter strains, fermentation conditions, and recipes. Researchers have called for rigorous, standardized studies and consistency in how studies are designed to more clearly link sourdough to specific health benefits.
3. Provides Gut-Friendly Prebiotics
“Sourdough starters contain live bacteria known as probiotics, but when the dough is baked, the bacteria die, leaving behind prebiotics,” VanBeber says. “Prebiotics are fibers in foods that feed healthy bacteria that are in our gut.”
These prebiotics support gut health, aid digestion, and increase absorption of vitamins and minerals from our diet. Research shows that adequate prebiotic consumption can lower the glycemic index of foods, which may help stabilize blood sugar, support a healthy immune system, and even reduce the risk of colorectal cancer.
Fiber-rich foods like fruits, vegetables, beans, nuts, seeds, legumes, and whole grains are all good sources of prebiotics.
4. Increased Bioavailability of Minerals
Wheat naturally contains phytic acid, and the fermentation process in sourdough helps reduce its levels, which may improve mineral bioavailability.
“Phytic acid binds to minerals like iron, zinc, and magnesium, which are naturally present in bread,” Zenker says. “Sourdough fermentation activates the phytase enzyme, which reduces phytic acid content, making it easier to absorb more of the minerals from sourdough bread than from other types of bread, like white bread. The effect is small but present, especially in whole-grain sourdough.”
This reduction in phytic acid is one of the reasons that sourdough may offer a slight nutritional advantage over conventionally made bread. While the improvement is modest, it can be meaningful for people who regularly choose whole‑grain sourdough as part of their diet.
