It isn't clear what effect white or brown bread has on the well-being of those who eat it and people can respond in different ways to certain types
White bread could be just as healthy as trendy whole wheat for some people - depending on who you are, suggests a new study.
Researchers say that it isn't clear what effect different types of bread can have on the well-being of those who eat it.
Even more surprisingly, people can react differently to the same bread, meaning that for some of us, white bread could be the best choice.
The new study, published in the journal Cell Metabolism, was a comprehensive, randomised trial involving 20 healthy people, comparing differences in how processed white bread and artisanal whole wheat sourdough affect the body.
Most people believe brown bread is best (Photo: Dorling Kindersley)
The researchers found the bread itself didn't greatly affect the participants and that different people reacted differently to the bread.
The research team then devised an algorithm to help predict how people may respond to the bread in their diets.
All of the participants in the study normally consumed about 10 per cent of their calories from bread.
Half were assigned to eat an increased amount of processed, packaged white bread for a week - around 25 per cent of their calories - and half to consume an increased amount of whole wheat sourdough, which was baked especially for the study and delivered fresh to the participants.
After a fortnight without bread, the diets for the two groups were reversed.
Before the study and throughout the time it was ongoing, several health effects were monitored including wake-up glucose levels; levels of the essential minerals calcium, iron, and magnesium; fat and cholesterol levels; kidney and liver enzymes; and several markers for inflammation and tissue damage.
The researchers also measured the make-up of the participants' microbiomes before, during, and after the study.
Study co-senior author Professor Eran Segal, of the Weizmann Institute of Science in Israel, said: "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.
Three soft white bread rolls
Will you be switching back to white bread? (Photo: Shutterstock)
"We looked at a number of markers, and there was no measurable difference in the effect that this type of dietary intervention had."
Based on some of their earlier work, however, which found that different people have different glycemic responses to the same diet, the researchers suspected that perhaps the glycemic response of some of the people in the study was better to one type of bread and some better to the other type.
A closer look indicated that this was indeed the case.
About half the people had a better response to the processed, white flour bread, and the other half had a better response to the whole wheat sourdough. The lack of differences were only seen when all findings were averaged together.
Co-senior author Doctor Eran Elinav, of the Weizmann Institute, said: "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.
"To date, the nutritional values assigned to food have been based on minimal science, and one-size-fits-all diets have failed miserably."
He added: "These findings could lead to a more rational approach for telling people which foods are a better fit for them, based on their microbiomes."
But co-senior author Professor Avraham Levy added: "These experiments looked at everyone eating the same amounts of carbohydrates from both bread types, which means that they ate more whole wheat bread because it contains less available carbohydrates.
"Moreover, we know that because of its high fibre content, people generally eat less whole wheat bread.
"We didn't take into consideration how much you would eat based on how full you felt. So the story must go on."