However, further investigations based on previous work, which found that different people have different glycaemic responses to the same diet, found that glycaemic response of some of the people in the study were better to one type of bread, and some better to the other type.
The researchers measured glucose, fat and cholesterol levels, and discovered there were no clinically significant differences between the effects of the two types of bread.
Half of them were given increased amounts of fresh whole-wheat sourdough bread to consume for a week, while the rest were given the same portion of processed white bread.
They selected 20 healthy participants who were regular bread eaters - getting about 10 percent of their calories from the bread, a globally typical figure. They were then given a two-week break before the two groups' diets were reversed.
The team examined how quickly people's blood sugar levels rose when they ate white bread for a week versus when they ate sourdough bread, which had previously been billed as the healthiest of breads. It has been the long-held belief that processed and refined foods caused a high glycemic response while unprocessed did not.
But overall, there was very little difference between effect of the two types of bread.
"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", said Eran Elinav, another senior study author and a researcher in the department of immunology at the Weizmann Institute.
After years of being cast aside as the less healthy bread option, white bread may finally get its moment of redemption.
Researchers found that the glycemic response - the effect that food has on blood sugar - of some of the people in the study was better to one type of bread, and some better to the other type.
Surprisingly, the researchers found that different people responded to different breads in contrasting ways. Tthe study actually gave people more sourdough, however, since it was created to have equal amounts of carbohydrates in each two week period, and whole wheat has lower concentrations of available carbohydrates for a given weight.
Some will react better to white bread, while others will benefit more from whole wheat.
Segal said this approach makes a lot more sense than putting everyone on "one-size-fits-all diets [which] have failed miserably".
"Epidemiological research has shown that people who eat more whole grains, such as whole grain breads, crackers, cereals, brown rice and quinoa, have a reduced risk of type 2 diabetes, heart disease, inflammation, obesity and certain cancers", Heller noted.
Dr Elizabeth Lund an independent consultant in Nutrition and Gastrointestinal Health commented that it was interesting that the bacteria in the gut seemed to predict how individuals may respond to bread consumption.