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Which bread is healthier? It may depend on you, says a new study

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The Weizmann Institute of Science released the results of a new study that looked at the health effects of white versus wholegrain bread

Cork, Ireland

Rehovot, Israel – White bread or whole grain? While one has received a bad rap in recent years, the other isn’t necessarily the best option for everyone.

A new study released by the Weizmann Institute of Science has found “that there is no difference between the health effects of” whole grains and white bread. In a statement, the Institute goes onto explain that choosing whole grain is “not necessarily the healthiest for everyone.”

The study had Weizmann Institute scientists compare two kinds of bread “on opposite sides of the health spectrum.” One of the breads was industrial-made white bread and the other was “sourdough-leavened bread made in an artisanal bakery from freshly stone-milled whole grain wheat flour and baked in a stone hearth oven.” This option was specially made for the study.

The scientists had 20 study participants consume about a quarter of their caloric intake in bread for a week. One group had the white bread and the other group had the sourdough bread.


The participants then took a two-week break and switched to the other bread option.

The statement says follow up tests “revealed that eating bread of any kind affected the blood levels of sugar, minerals, liver enzymes and other substances. But when the scientists compared the effects of the two types of bread, they were surprised.”

Eran Segal, a professor at the institute’s Computer Science and Applied Mathematics Department says the scientists were all taken aback by the results. They expected to find that the sourdough bread was the better option.

“… Much to our surprise, we found no difference between the health effects of the two types of bread,” says Segal.

The scientists say in the statement that our body’s response to bread is going to be different for everyone.

“…The body’s response to bread is a highly personal matter, so the differences between people in the study averaged themselves out,” says Dr. Eran Elinav of the Immunology Department, who headed the study with Segal and Avraham Levy, a professor in the Plant and Environmental Sciences Department.

In the statement, Levy adds: “We planned the experiment so that everyone would consume the same amount of available carbohydrates from both bread types. Because whole wheat bread contains relatively fewer carbohydrates, this meant that people ate more of it compared to the white bread. This difference in carbohydrate levels should also be taken into consideration when planning a diet.”


The study showed, for example, “that about half of the participants had higher blood sugar levels after eating white bread, whereas the other half had higher blood sugar after eating sourdough bread,” says the statement.

The scientists say that the difference in responses was due to “the individuals’ intestinal microbes – the microbiome. The composition of the microbiome in the people whose response to white bread produced high blood sugar levels differed from that of the people who responded to sourdough bread with high blood sugar.”

The statement says the scientists developed an algorithm connecting the microbiome’s composition with the person’s response to the type of bread.

“Using this algorithm, we managed to predict who will have high blood sugar after eating white bread, and who will have high blood sugar after eating the sourdough,” says research student Tal Korem in the statement.

Korem conducted the study with research student Dr. David Zeevi and other team members: Dr. Omer Weissbrod, Noam Bar, Maya Lotan-Pompan, Dr. Tali Avnit-Sagi, Noa Kosower, Gal Malka, Michal Rein and Dr. Adina Weinberger of the Computer Science and Applied Mathematics Department; and Dr. Niv Zmora and Jotham Suez of the Immunology Department.


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