William Wade, an oral microbiologist at King’s College London Dental Institute, says the study is a “major technical achievement,” but takes issue with the analysis. He argues that changes to oral microbial communities are probably more the result of changes in oral hygiene practices than diet. “It might appear obvious that the food we eat is used as nutrients by oral bacteria, but, in fact, diet has remarkably little influence on the composition of oral microbiota,” he says—though sugars are an exception. “A more plausible explanation for the differences seen is the effect of modern oral hygiene, particularly the use of toothbrushes and detergent-containing toothpastes.” Such practices constantly remove plaque, says Wade, resulting in an immature microbial community that happens to provide the perfect environment for streptococci, a group whose numbers fall in overall proportion as plaque is allowed to build up.