Is white bread really that bad for you? It depends on your gut bacteria

You always opt for whole wheat bread because you’re told it’s healthier for you. But is white bread all that bad?

A new study suggests that not all people respond badly to white bread – in some cases, it doesn’t lead to surges in blood sugar levels at all. It all depends on your gut microbiome.

“The findings for this study are not only fascinating but potentially very important because they point toward a new paradigm: different people react differently, even to the same foods,” Eran Elinav, one of the study’s senior authors said.

“To date, the nutritional values assigned to food have been based on minimal science, and one-size-fits-all diets have failed miserably,” he said.

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Elinav and his team out of the Weizmann Institute of Science worked with 20 volunteers to see how they’d react to processed white bread and artisanal whole wheat sourdough bread.

The study participants already ate about 10 per cent of their calories from bread daily. Half of the group ate packaged white bread for a week, making up about 25 per cent of their calories while the other half ate whole wheat sourdough bread baked especially for the study and delivered fresh to the participants.

After two weeks without bread, the diets for the two groups were swapped.

They had to eat the bread for breakfast every morning, sometimes with butter. They couldn’t eat the night before and they also had to abstain from food for about two hours after eating bread. They couldn’t even exercise because these are all factors that tamper with glycemic response.

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Before the study and throughout it, the researchers were monitoring glucose levels, intake of calcium, iron and magnesium, fat and cholesterol levels, and kidney and liver enzymes – all markers for inflammation and tissue damage.

Turns out, there wasn’t much of a difference between the two breads – some people didn’t even have a bad glycemic response to white bread.

“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,” Eran Segal, a biologist working on the study, said.

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Different people had different responses, though. Some people responded well to one bread, while others didn’t because of their gut bacteria. This is the collection of natural bacteria living in your intestines.

With their findings in tow, the researchers say you shouldn’t swear off specific foods, especially if not everyone responds to certain foods the same way. Dietary choices should differ by person, they say.

Don’t confuse multi-grain and whole wheat with whole grain either. Multigrain means that the product in hand has many different grains – corn, rice, wheat, barley, for example.

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Whole grain is what consumers should be looking for. In this case, the whole grain includes the outer skin of the kernel (the bran), the vitamin-packed, protein and fat-rich sprout (or the germ), and the endosperm, packed with minerals and carbohydrates.

Multigrain options could also include processed products that are stripped of the bran and germ.

Read the full findings in the journal Cell Press.

carmen.chai@globalnews.ca
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