Does Fluoride Harm the Brain? Scientists Have a New Answer

For decades, adding fluoride to drinking water has been considered one of the most effective public health measures for preventing cavities and reducing tooth decay. In recent years, however, the discussion has expanded beyond dental health, with some researchers and members of the public raising questions about whether fluoride could affect brain development or long term cognitive function.

Now, a new review by the Davidson Institute for Science Education, based on decades of data from more than 10,000 participants in Wisconsin, found no evidence that standard levels of water fluoridation are associated with reduced cognitive abilities.

Why Is Fluoride Added to Drinking Water?

Our teeth are constantly undergoing a cycle of wear and repair. Bacteria in the mouth produce acids that gradually dissolve minerals from tooth enamel.

Fluoride, a naturally occurring mineral found in rocks and water, helps strengthen tooth enamel and supports the body's natural repair process, making teeth more resistant to decay.

The connection between fluoride and dental health was first identified in the early twentieth century. Since the 1940s, many countries have added controlled amounts of fluoride to public drinking water to reduce cavities.

The World Health Organization recommends fluoride concentrations of 0.5 to 1 milligram per liter for community water fluoridation, balancing the benefits for dental health while minimizing the risk of dental fluorosis, a condition that can cause mild discoloration of tooth enamel after excessive exposure.

What Did the New Study Find?

In recent years, several studies have explored whether fluoride exposure might affect the brain.

Some attracted significant public attention, but many researchers noted important limitations. Several were conducted in areas with unusually high natural fluoride levels and did not fully account for other factors that could influence cognitive development, including nutrition, environmental exposures, or socioeconomic conditions.

The new study sought to address those concerns by following more than 10,000 participants over several decades.

Researchers examined IQ scores from adolescence through approximately age 80 and found no association between growing up in communities with standard fluoridated drinking water and declines in memory, intelligence, or other measures of cognitive function later in life.

Important Limitations

Like all research, the study has limitations.

The researchers estimated fluoride exposure based on where participants lived rather than measuring fluoride levels directly in their bodies. As a result, individual exposure may have varied.

Even so, one of the study's greatest strengths is that it focused specifically on fluoride concentrations commonly used in public water fluoridation programs rather than unusually high natural levels.

What About Israel?

Fluoridation policy in Israel has changed several times over the years.

Following the widespread use of desalinated water and the cancellation of mandatory water fluoridation, fluoride levels in much of the country's drinking water are now lower than they were in the past.

Israel's Ministry of Health has expressed support for restoring community water fluoridation in accordance with the recommendations of many dental and public health professionals, but such a program has not yet been reinstated.