Sourdough is just white bread

Friday, June 9th, 2017

I would have assumed that sourdough bread and ordinary white bread were nutritionally very, very similar, but wild yeast strains and bacteria that fill sourdough with sour acids purportedly reduce its glycemic index. Or so scientists thought, until a recent study found otherwise:

In a study led by students Tal Korem and David Zeevi, the Israeli team picked two extremes from the bread world. They hired a local baker to prepare artisanal sourdough from whole-grain flour. They also bought mass-manufactured loaves of white bread, made from refined flour and loaded with preservatives.

The team recruited 20 volunteers and asked half to spend a week eating the white bread and another eating the sourdough. The other volunteers did the same in the reverse order. Before and after each bread-filled week, the team took a census of the bacteria in each volunteer’s gut, as well as measured 20 variables including blood pressure, weight, blood sugar, cholesterol, triglycerides, and various hormones. They found that the bread the participants ate had no significant effect on any of these factors. Even the microbiome, which can shift quickly and extensively after a change in diet, was barely affected by the choice of breads.


  1. I thought sourdough was just the American term for white bread. (What Americans call white bread seems to be some kind of inferior cake).

  2. Steve MqCueen says:

    Sourdough is to bread as lambic is to beer. Both rely on wild yeast and bacteria to ferment the sugars in the dough or wort, rather than on cultivated yeast strains. The sourness in both is due to the presence of lactic acid, which is produced by the bacteria present.

  3. Abelard Lindsey says:

    There is sourdough bread and then there is San Francisco sourdough bread.

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