FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols—poorly absorbed sugars and fibers found in certain grains, fruits, and vegetables, along with some dairy products and artificial sweeteners. When these carbohydrates—like those found in wheat—are fermented by bacteria, they produce gas and attract water when they pass through the gut, causing the bowel to stretch, says Jane Varney, senior research dietitian at Monash University.
If you have a normal gut, this stretching and expanding isn’t a problem. But those with IBS sometimes have visceral hypersensitivity, Varney says. Simply put, if you have a sensitive gut, this extra water and gas can cause you more pain than your digestively blessed friend who just ate the same whole wheat sandwich.
What makes sourdough easier to digest?
The wild yeast and bacteria in a sourdough starter break down some of the carbohydrates and proteins found in flour, says Kate Scarlata, a Boston-based dietitian and author of The Low-FODMAP Diet book. When bread is made with fast-rising yeast, the bacteria don’t have time to do any pre-digesting.
“When you add baker’s yeast, that speeds the process of the rising of the bread, and it doesn’t give the fermenting event enough time to really happen,” Scarlata says. “It should be a 12-hour-plus process for best digestibility.”
The process also breaks down a carbohydrate found in wheat called fructan. “We know from our research that in a large proportion of people it’s the fructans in foods that they’re sensitive to as opposed to the gluten,” Varney says. When you limit foods containing gluten, you also limit exposure to fructans, which will help symptoms in those people.
What are the health benefits of sourdough?
Bacteria are often considered germs or disease agents, says Anne Madden, a researcher with the Sourdough Project at North Carolina State University’s Rob Dunn Lab. But often bacteria ward off other, harmful bacteria and help make some food more nutritious.
“Unlike standard yeast bread, sourdough has a community inside of it,” Madden says.
The process also increases the body’s ability to absorb vitamins and minerals from the bread. As the dough ferments, it produces enzymes that break down phytic acid. Phytic acid can lead to gas production in those with IBS and can inhibit the body’s ability to absorb nutrients, according to Kimbell in her new book The Sourdough School.
Basically, you poop out all the good stuff.
Last, if you’re trying to control your blood sugar, sourdough is a better option than fast-fermented breads. Research shows sourdough has higher levels of resistant starch than other breads, especially when whole grains are used. This means blood sugar levels spike less because it takes the body longer to digest the carbohydrates.