Full disclosure: The research in this area is pretty limited. But the data we have is promising, says Means, who cites a 2015 study in the journal Cell. In this experiment, researchers put continuous glucose monitors on 800 healthy participants and gave them the same meals in terms of composition (aka, the same ratio of carbs to fiber to protein), assuming they would respond exactly the same.
“You would think that they would all respond exactly the same, because all the meals had the same number of carbohydrates in them,” Means recounts. But actually, people had varying responses across the board–from no spikes to gigantic jumps. When the researchers took a look at which factors could predict these wildly different levels, they found that microbiome composition seemed to dictate those responses.
“[This] is not surprising,” says Means. “The microbiome [does] a first pass on food. They’re the ones who break down some of those early carbohydrates before it actually goes into the body.” Perhaps that’s why she can eat “a can of beans” and see no glucose response, while others eat one serving and find their blood sugar sky-high. “I think that people who are used to eating lots of plant fiber probably have microbiomes that tend to process it a little bit more favorably,” she adds.