Benefits of Fluoride Aren't What They Used to Be

There was a time when adding fluoride to drinking water had very clear dental health benefits, but that time might have ended close to 50 years ago, researchers say. A study published by the Cochrane Collaboration found that before 1975, adding fluoride to tap water reduced the number of decayed baby teeth by 2.1 per child, the Guardian reports. But after fluoride toothpaste became more widely available in the '70s, the reduction in decayed teeth was an average of just under a quarter of a tooth per child. Researchers looked at 159 studies, covering almost 3,000 children in the UK and Australia, that compared areas where fluoride has been added to tap water with those that don't have fluoride-infused water.

"Adding fluoride to water may slightly increase the number of children who have no tooth decay in either their baby teeth or permanent teeth," researchers wrote. "However, these results also included the possibility of little or no difference in tooth decay." The Guardian notes that adding fluoride to drinking water, which began in the US in 1945, has long been considered a major public-health achievement. Study co-author Anne-Marie Glenny, however, says "it is important to think about the wider context and how society and health have changed over time."

• "Most of the studies on water fluoridation are over 50 years old, before the availability of fluoride toothpaste," says Glenny, a professor of health sciences research at the University of Manchester. "Contemporary studies give us a more relevant picture of what the benefits are now."

• The study comes as fluoridation is under increasing scrutiny in the US, CNN reports. A federal report recently linked high levels of fluoride—around twice the recommended maximum—to lower IQs in children. Last month, a judge ordered the EPA to step up regulation of fluoride in drinking water.
• Organizations including the American Academy of Pediatrics still support adding fluoride to water. The study's authors say municipalities shouldn't see their findings as a reason to end the practice, NBC News reports. "There's no evidence to suggest that where water fluoridation programs are in place, that they should necessarily be stopped," Glenny says.

(More fluoride stories.)