For decades, dentists have drummed the same advice into Americans: Brush regularly and floss nightly because doing so helps prevent cavities and gum disease.
Then the Associated Press investigated the claims for floss and found: The evidence for flossing is “weak, very unreliable,” of “very low” quality and carries “a moderate to large potential for bias.”
Our favorite moment in this floss beatdown: The federal government has recommended flossing since 1979, lately in the Dietary Guidelines for Americans. But that recommendation must be based on scientific evidence. After AP inquiries, the feds removed the flossing recommendation from the guidelines this year … and admitted to the AP that “the effectiveness of flossing had never been researched, as required.”
So the floss spool now joins a long and growing list of modern medical (and dietary) pronouncements that have proven to be unsubstantiated.
Last year, the nation’s top nutrition advisory panel eased off its warnings about cholesterol, after years of warning egg-craving Americans to skip the omelet. Dietary cholesterol can no longer be considered a “nutrient of concern.”
The thinking on salt, too, has evolved. (The zealous drive to limit our salt intake has little basis in science.) On fats, too. (Those low-fat, high-carb diets may not prevent heart attacks. Even saturated fats in small amounts may be relatively harmless.)
In the realm of prevention, there are huge scientific battles over the benefits of mammograms and prostate screening for all.
Skepticism about everything from floss to fat is healthy.
Medicine often advances fitfully, but some prescriptions never change. For instance: The U.S. Surgeon General last year recommended a terrific pill-free way to improve your blood pressure, your mood and your overall health: Walk.
Twenty minutes a day helps older people maintain their mobility. A brisk walk every day helps people curb their weight.
Just 150 minutes of moderately intense physical activity a week — that includes brisk walking — is enough to bring health benefits that can reduce the risk of disease and death. That way, you’ll have many more years to decide every night: Should I floss or not?