While regular bread is fermented by a specific baker’s yeast (Saccharomyces cerevisiae), sourdough bread is fermented by a mix of lactic bacteria and yeast, which provides certain additional nutritional advantages.

Sourdough bread has a lower glycaemic index than regular bread(1,2). This means that it releases its energy more progressively over a longer period and requires less insulin. This effect produces a feeling of being full for longer, which makes it easier to avoid snacking between meals. Moreover, the vitamins and minerals in sourdough bread are more easily absorbed by the body, and the body can also make better use of them(3,4,5). The presence of microorganisms in sourdough suggests a beneficial influence on the intestinal flora (or microbiota), which results in some additional health benefits. It is often thought that sourdough bread is easier to digest, but this has not been clearly confirmed.

1. Adam et al, 2003. Les possibilités d'amélioration de la valeur nutritionnelle des pains. Cahiers de nutrition et de diététique, 38(5), 316-322.
2. Rizkalla et al., 2007. Effect of baking process on postprandial metabolic consequences - randomized trials in normal and type 2 diabetic subjects. European Journal of Clinical Nutrition, 61, 175–183
3. Lopez et al., 2000. Strains of LAB isolated from sourdough degrade phytic acid and improve calcium and magnesium solubility from whole wheat flour. Journal of Agriculture and Food Chemistry. 48, 2281-2285.
4. Lopez et al., 2001. Prolonged fermentation of whole wheat sourdough reduces phytate level and increases soluble magnesium. Journal of Agriculture and Food Chemistry, 49, 2657-2662.
5. Lopez et al., 2003. Making bread with sourdough improves mineral bioavailability from reconstituted whole wheat flour in rats. Nutrition, 19, 524-530.