The Star’s view:
Story of floss’s fall from grace offers much to learn about scientific studies,
The revelation this week that flossing may have limited dentalhealth benefits, if any, elicited a mix of regret and skepticism. Regret because why have we wasted so much time and energy either flossing or feeling guilty about not flossing? And skepticism because of the seeming inevitability that another study will emerge in the days or weeks to come that says precisely the opposite.
Wine, tea, milk, tomatoes, coffee, butter — these are among the many foods that have been shown by some scientific studies to cause cancer and by others to cure it. One day headlines declare salt a panacea, the next a poison. Now we are being asked to believe that our dentists’ endless floss-flogging has been based on mere tradition? The constant barrage of contradictory information is enough to shake one’s faith in science.
Except the problem isn’t really science, but what masquerades as it. Not every study is created equal and unrigorous or biased experimentation can produce just about any result. The website 538.com recently used the standard, if imperfect, methods of nutrition research to find several “statistically significant” correlations that were not real, for instance between drinking lemonade and believing that the film Crash deserved to win the best picture Oscar. No wonder multiple Coke-funded studies have concluded, wrongly, that exercise rather than diet is the best way to lose weight.
Meanwhile, scarce funding and the competitive academic job market have prompted many practitioners to exaggerate the significance of their findings in an effort to get attention. A recent study in the British Medical Journal found more than one third of 462 press releases from top U.K. universities contained exaggerations — a claim that’s at least 67 per cent believable.
And of course we in the media bear some of the responsibility. Too often we report studies out of context or without acknowledging their limitations. Too often in our search for sexy headlines, we forget that science is an incremental, fundamentally unsexy enterprise. A study is far more likely to provide another small piece in a vast, complex puzzle than it is to be “revolutionary.”
So how are we to sort the good from the bad, the true from the false? On this score, the floss story has something to teach us. In its reporting, the Associated Press looked at the 25 most robust studies, not just the latest one. These included several so-called “systematic reviews,” which bring together the best science on a particular issue and examine the aggregate data, thus mitigating the flaws and biases of any individual experiment.
The conclusion? Not that floss doesn’t work, but that the evidence that it does is weak. The story even quotes several medical professionals who say the potential benefits, though unproven, still appear to justify the low cost. Rigorous, cautious, qualified, even a bit boring: now that’s good science.