Sourdough’s long fermentation and rising time leads to changes in the bread that don’t occur in conventional yeast-leavened bread. 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 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 butter 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,” Jarosh says.
