Hidden in the Crust: Why Your Bread Choice Matters

Your morning toast could be doing more than satisfying hunger. While most breads spike blood sugar and trigger digestive issues. Recent studies show sourdough bread, through its traditional fermentation process, may offer several health advantages, according to research published in the Journal of Nutrition.

"It's easy to incorporate sourdough into meals—top toasted sourdough with cottage cheese and tomato, mashed cannellini beans, or a runny egg," says Elizabeth Barnes, RDN, medical expert at at Verywell Health.

The fermentation process involves lactic acid bacteria and yeast, which produce prebiotic properties that enhance gut health, according to a 2023 study. While high baking temperatures eliminate most probiotic bacteria, the bread retains prebiotics supporting digestive function.

Medical research indicates the fermentation process breaks down non-digestible carbohydrates in flour, called FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). This makes sourdough potentially easier to digest than conventional bread for individuals with non-celiac gluten sensitivity or irritable bowel syndrome.

Nutritional analysis shows sourdough bread contains fewer antinutrients than other varieties. These compounds, including phytic acid, typically block absorption of minerals like iron, zinc, and calcium. The natural fermentation process reduces these antinutrients.

Blood sugar studies demonstrate sourdough bread has a lower glycemic index than other bread types. According to research from the University of Michigan, a 30-gram serving of sourdough measures 54 on the glycemic index, compared to 71 for whole wheat bread.

A standard slice of toasted sourdough bread (59 grams) contains:

• 188 calories
• 7.67 grams of protein
• 1.26 grams of fat
• 36.5 grams of carbohydrates
• 1.8 grams of fiber Source: USDA National Nutrient Database

The bread provides 13% of the recommended daily iron intake and contains significant amounts of B vitamins essential for red blood cell formation, according to the National Institutes of Health.

Health considerations exist for specific populations. Many commercial varieties contain high sodium levels, making them unsuitable for individuals on low-sodium diets. While fermentation reduces gluten content, people with celiac disease or wheat allergies should avoid traditional sourdough.

Research published in the Journal of Nutrition suggests whole wheat sourdough bread, when included in a Mediterranean-style diet, may help manage blood sugar levels and support digestive health. However, nutrition experts recommend portion control, particularly for individuals managing carbohydrate intake or weight.