Nav: Home

Bread and health: A personal matter

June 07, 2017

Bread occupies a unique place in our diet: it accounts for about one-tenth of the calories many people in the West consume and up to 40% of the caloric consumption in some non-Western countries - more than any other food product. In the past few decades, since white bread has acquired a bad name, bakeries have been going out of their way to produce high-quality whole grain breads. But a new study conducted at the Weizmann Institute of Science and published recently in Cell Metabolism reveals that these "wholesome" choices are not necessarily the healthiest for everyone.

The Weizmann Institute scientists compared two kinds of bread viewed as being on opposite ends of the health spectrum. One was industrial white bread made from refined wheat and considered less healthy. 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: It was prepared specially for the study and was assumed to possess superior properties.

Twenty study participants were divided into two groups and asked to consume large quantities of bread (supplying about a quarter of their caloric intake) for a week. One group ate the white bread, and the other, the "healthy" sourdough bread. After a two-week break, they switched, and for a week the group that had previously eaten white bread ate the sourdough bread, and vice versa.

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. "We were sure that the sourdough bread would come out a healthier choice, but much to our surprise, we found no difference between the health effects of the two types of bread," says Prof. Eran Segal of Weizmann Institute's Computer Science and Applied Mathematics Department.

"That's probably because 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 Prof. Segal and Prof. Avraham Levy of the Plant and Environmental Sciences Department. 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. It is possible that these different responses were due, in part, to the differences in 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 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, who 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.
-end-
Prof. Eran Segal's research is supported by the Crown Human Genome Center, which he heads; the Else Kroener Fresenius Foundation; the Adelis Foundation; Donald L. Schwarz, Sherman Oaks, CA; Jack N. Halpern, New York, NY; Leesa Steinberg, Canada; and the European Research Council.

Dr. Eran Elinav's research is supported by the Leona M. and Harry B. Helmsley Charitable Trust; the Adelis Foundation; the Else Kroener Fresenius Foundation; John L. and Vera Schwartz, Pacific Palisades, CA; the Rising Tide Foundation; Andrew and Cynthia Adelson, Canada; Yael and Rami Ungar, Israel; Leesa Steinberg, Canada; Jack N. Halpern, New York, NY; and the Lawrence and Sandra Post Family; the Bernard M. and Audrey Jaffe Foundation; the European Research Council; and the Estate of Bernard Bishin. Dr. Elinav is the Incumbent of the Rina Gudinski Career Development Chair.

Prof. Avraham Levy's research is supported by the Dr. Erhard, Emmi, and Fred Loewinsohn Center for Pediatric Health, which he heads; the Y. Leon Benoziyo Institute for Molecular Medicine, which he heads; the Tom and Sondra Rykoff Family Foundation Fund; the Leona M. and Harry B. Helmsley Charitable Trust; Dana and Yossie Hollander, Israel; and the European Research Council. Prof. Levy is the incumbent of the Gilbert de Botton Professorial Chair of Plant Sciences.

Weizmann Institute of Science

Related Eating Articles:

Face up to eating disorders, and seek help
A new study has found young people are leaving it 'too late' to seek help for eating disorders, citing fear of losing control over their eating or weight, denial, and failure to perceive the severity of the illness as reasons not to get professional advice.
Memory games: Eating well to remember
A healthy diet is essential to living well, but should we change what we eat as we age?
Eating disorders linked to exercise addiction
New research shows that exercise addiction is nearly four times more common amongst people with an eating disorder.
Review of 96 healthy eating studies finds 'nudges' yield best changes in eating habits
A gentle nudge in the right direction is sometimes all people need.
Why young men aren't eating their five-a-day
A new study reveals why young men aren't eating their five-a-day.
Unexpected nut eating by gorillas
Scientists from the Max Planck institute for Evolutionary Anthropology and Washington University in St.
Is 'clean eating' just dirty rhetoric?
Study looks at #cleaneating as a healthy or harmful dietary strategy and explores perceptions of clean eating and associations with disordered eating among young adults.
Eating healthily at work matters
A new study in the American Journal of Preventive Medicine, published by Elsevier, demonstrated that employees at a large urban hospital who purchased the least healthy food in its cafeteria were more likely to have an unhealthy diet outside of work, be overweight and/or obese, and have risk factors for diabetes and cardiovascular disease, compared to employees who made healthier purchases.
Eating later in the day may be associated with obesity
Eating later in the day may contribute to weight gain, according to a new study to be presented Saturday at ENDO 2019, the Endocrine Society's annual meeting in New Orleans, La.
Eating fish may help prevent asthma
A scientist from James Cook University in Australia says an innovative study has revealed new evidence that eating fish can help prevent asthma.
More Eating News and Eating Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.