Which bread is most healthful: artisanal whole wheat sourdough, or processed white? It depends apparently, on who’s eating it. Science Daily reports that researchers at the Weizmann Institute of Science divided a group of 20 healthy subjects in two, and gave half an increased amount of processed, packaged white bread for a week — around 25% of their calories — and half an increased amount of whole wheat sourdough. Two weeks later, the groups swapped bread type. Researchers monitored 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. They also measured the makeup of the participants’ microbiomes before, during, and after the study.
“The initial finding 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, 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 up with that? A closer look indicated that 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 point toward a new paradigm: different people react differently, even to the same foods,” says Eran Elinav, 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.”