White or whole wheat bread? it all depends on your microbiota!
Researchers are revising our beliefs about the benefits of these two kinds of bread for the body.
Cardiovascular diseases, diabetes, cancer… White bread is continually accused of favoring the onset of these diseases, through elevated postprandial blood sugar (an increase in blood sugar after a meal), while whole wheat bread is praised for possessing every possible virtue. But these assertions have no real basis in fact, say the authors of a new study published in Cell Metabolism. Basing their work on a recent discovery--according to which there is an extreme interindividual variation in postprandial glycemic response--the researchers compared the effects of white bread and whole wheat bread on 20 volunteers according to a range of clinical parameters and disease markers, as well as the composition and function of their intestinal microbiota.
The researchers observed several things:
- Whether it be white or whole wheat, eating bread alters blood markers, but not enough to have a clinical impact.
- More surprisingly, the food didn’t change the composition of the microbiota, a testament to its impressive stability in the face of nutritional changes.
- Above all, the glycemic response didn’t depend on the food, but rather on the nature of the microbiota. As a result, it varies from one individual to another and is impossible to predict.
These discoveries contradict our received ideas that “whole wheat bread is good for you” and “white bread is bad,” and highlight the importance of personalizing nutritional advice.
Korem et al. 2017, Cell Metabolism 25, 1243-1253, June 6, 2017 http://dx.doi.org/10.1016/j.cmet.2017.05.002