The reason so much established nutrition info gets over-turned, often dramatically, is that so many nutrition study results are, well, let’s just say, faulty.
Because the findings are based on asking people to report what they eat (or ate) and besides the fact that people have very faulty memories for things that don’t matter that much to them (like what they need to remember for a survey they are taking), there’s also the fact that everyone – and I do mean everyone – lies in surveys in order to look better to the people doing the survey, and yes, this happens even in, perhaps especially in, surveys in which the person giving the answer is anonymous.
Anonymity, alas, does not make for a lot more honesty.
So whenever you read a study that was based on a food questionnaire, always use a great deal of caution before buying the results completely.
And yes, of course, I floss and brush my teeth three times a day.
And exercise at least 30 minutes a day.
Hey, would I lie to you?