Study Casts Doubt on Whole Grain Bread’s Edge Over White Bread

John Egan - The Upside Blog

by | Updated: September 1st, 2017 | Read time: 4 minutes

A new study has sliced through decades-long consternation over whether white bread or whole grain bread is better for you.

Research released recently by Israel’s Weizmann Institute of Science suggests white bread, which has earned fairly low grades for its dietary benefits, might be just as healthy as whole grain bread. However, some experts say it might be a half-baked idea to abandon whole grain bread altogether based on the findings of this study.

Person Waiting for Breakfast with Three Slices of White Bread Toast in Toaster |

In the Weizmann Institute study, published in the journal Cell Metabolism, scientists baked two types of bread: white bread made from refined wheat flour and sourdough-leavened bread made from stone-milled whole grain wheat flour.

Twenty study participants were split into two groups and asked to consume large quantities of the bread for one week. One group ate the white bread, and the other ate the whole grain bread. Then, the groups switched the kinds of bread they consumed for another one-week period.

What the researchers discovered was unexpected.

“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,” Eran Segal, a Weizmann Institute professor who co-led the study, says in a news release.

Eran Elinav, another Weizmann Institute professor and study co-leader, explains why there was no difference: How the body responses to bread “is a highly personal matter,” so any differences that showed up in the study “averaged themselves out.”

Segal, Elinav and their research colleagues say half of the study participants had higher levels of blood sugar after eating white bread, while the other half had higher levels of blood sugar after eating whole grain bread. They theorize that the disparity was due, in part, to variations in each participant’s gut bacteria.

“When it comes to nutritional science, this study shows that one size does not fit all,” says registered dietitian nutritionist Angel Planells, a national spokesman for the Academy of Nutrition & Dietetics.

But registered dietitian Beth Rosen suggests the “size” that fits most of us is whole grain bread, not white bread. The scale tips in favor of whole grain bread thanks to how the grains are processed, she says.

The difference between white and whole grain bread comes down to processing, Planells says. Each grain comprises three parts: bran, endosperm and germ. Whole grain bread includes all three parts, meaning it’s unrefined, while white bread includes only the endosperm, meaning it’s refined.

Due to the presence of bran and germ, whole grain bread contains fiber, whereas white bread does not. Scientific evidence shows the benefits of dietary fiber include the ability to reduce cholesterol levels, manage blood sugar levels and promote digestive health, according to Rosen.

“For the majority of people, eating at least half of your day’s intake of grain products from whole grain sources — whole wheat, brown rice, quinoa, oats, cornmeal — is beneficial to our health,” she says.

For those coping with digestive issues such as gastroparesis and diverticulitis, a low-fiber diet might be advisable, Rosen says. In that instance, white bread made with refined grains would be a wiser choice.

Jeff O’Connell, editor in chief of and author of “Sugar Nation,” says the study — if its findings are borne out — represents a “sea change” in how we view the health benefits of different kinds of bread. Based on the research, he notes, what’s good for one person’s glycemic level might not be good for another person’s, and vice versa.

In light of that, the study leaves bread-eating consumers with “greater uncertainty,” O’Connell says.

Typically, people who seek to consume “healthy” bread grab the whole grain bread at the grocery store and skip the white bread, he says. But unless you know your gut bacteria profile or your post-bread level of blood sugar — neither of which is simple to gauge — you can’t be certain that you’re buying the right bread, O’Connell says.

“For the time being, you’re left to guess,” he says.

Planells, the national spokesman for the Academy of Nutrition & Dietetics, says the study tells us that whether someone consumes white or whole grain bread, what may be more critical is what’s happening in your gut. Fortunately, according to Planells, plenty of “exciting and evolving” research on gut bacteria is coming out.

In the meantime, O’Connell recommends people pick whole grain bread rather than white bread.

“One study is not enough for me to completely upend a view of white versus whole grain that’s prevailed for decades,” he says.

The Cleveland Clinic points out that if you’re shopping for whole grain bread, you should pay close attention to the ingredient label. Primary ingredients such as wheat, oats, flax seeds, barley and buckwheat should be listed first, in order of the amount that the loaf contains, the clinic says.

Also, be wary of the terms “wheat” or “multigrain” plastered on packaging for loaves of bread, according to the Cleveland Clinic.

“They sound healthy, but they’re probably made with partially or mostly refined white flour,” the clinic says.

Regardless of whether you go with white or whole grain bread, experts warn against consuming too much of it; one slice of bread has roughly 15 grams of carbs. That advice is especially relevant for people who are struggling with obesity or diabetes, according to O’Connell, since overconsumption of carbs can exacerbate both conditions.

“Just be mindful of your portion sizes,” Planells says, “as it can be quite easy or tempting to polish off a large loaf of bread if you have some butter, olive oil or peanut butter lying around.