Study suggests little dietary significance between white and whole wheat bread

A new study published in the scientific journal Cell Metabolism by Weizmann Institute researchers reports that that the type of bread that is best for you may have more to do with your own body than the bread itself.

In the randomized trial, 20 people each ate a certain bread and then switched to the other kind. Half were assigned to consume an increased amount of processed, packaged white bread for a week and half to consume an increased amount of whole wheat sourdough. They did this for one week, then took a two-week break. After the break, each participant switched bread types and consumed the other one for another week.

Before, during, and after the trial, health effects were monitored. This included weight, blood pressure, glucose levels, mineral levels, kidney and liver enzymes, and signs of inflammation or tissue damage.

The researchers did not find any significant difference between the two groups. In terms of health outcomes, it didn’t matter which bread was consumed.

“The initial finding, and this was very much contrary to our expectation, was that there were no clinically significant differences between the effects of these two types of bread on any of the parameters that we measured,” says Eran Segal, a computational biologist at the Weizmann Institute of Science and one of the study's senior authors. “We looked at a number of markers, and there was no measurable difference in the effect that this type of dietary intervention had.”

“These findings could lead to a more rational approach for telling people which foods are a better fit for them, based on their microbiomes,” says Eran Elinav a researcher in the Department of Immunology at the Weizmann Institute and another of the study's senior authors.