Has any food (besides sugar, or course) been more maligned than white bread? Nutritionists have been telling us to eat whole wheat, pumpernickel, multi-grain... anything but white bread, for years. They tell us it'll make us fat, is nutritionally shallow, and how the bleaching process actually can make it toxic. Switzerland even taxes white bread more heavily to discourage its citizens from eating it. It is probably safe to say that if you are reading this, you have already written off white bread as anything beyond a sentimentally guilty pleasure served up with peanut butter and jelly.

But all that hasn't stopped researchers from researching it, and a recent investigation done by the Weizmann Institute of Science has thrown some new light – if not an out-and-out curve ball – into our understanding of your childhood lunchbox staple. The scientists discovered that the the bread itself didn't greatly affect the participants so much as different people just react differently to the bread.

The researchers pitted white bread against an artisanal whole wheat sourdough loaf. The metrics for comparison were extensive, and included: wakeup 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 scientists also measured the makeup of the participants' microbiomes before, during, and after the study.

"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," says Eran Segal, a computational biologist at WIS and one of the study's senior authors. "We looked at a number of markers, and there was no measurable difference in the effect that this type of dietary intervention had."

What's the science? The investigators suspect that 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. 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 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," says Eran Elinav, a researcher in the Department of Immunology at WIS and another of the study's senior authors. "To date, the nutritional values assigned to food have been based on minimal science, and one-size-fits-all diets have failed miserably."

Sound too good to be true, closet white bread lover? It might be. Avraham Levy, a professor in the Department of Plant and Environmental Sciences and another coauthor, added a caveat to the study: "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 fiber 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."

The research was published in Cell Metabolism.