IF YOU’D LIVED in Grand Rapids, Michigan, in 1945, you’d have been one of the first people in America to sip fluoridated tap water. As of 2024, about 73 percent of us get the mineral in our water supply. And for almost 80 years, there’s been nonstop drama around that addition. In 1956, Clive McCay, a researcher at Cornell University, wrote that water fluoridation “is being considered as a panacea by one party and a poison by another.” Yes, it is. Last year, TikTok posts described the mineral as “toxic.” On X, Health and Human Services secretary appointee Robert F. Kennedy, Jr., called it an “industrial waste” associated with numerous diseases. Dentists and many public health advocates say it’s very important for your health.
The controversies haven’t always been just about concerns for your teeth and body. Some people object to the government putting anything in the water. “There is something about water and the necessity of it for our lives that makes people particularly protective of the water supply,” explains Catherine Carstairs, PhD, a professor at the University of Guelph in Ontario, who has researched the history of fluoride. “Also, there’s a concern that it simply isn’t natural to put fluoride in the water, even though, ironically, the benefits of fluoride were discovered because it naturally occurs in many water supplies.” So what exactly is it, and what does it have to do with our health?
What Fluoride Is
THIS MINERAL, A form of the element fluorine, was found to prevent tooth decay and cavities in the early 1900s. (A dentist in Colorado saw that people whose water naturally had high levels of fluoride also had exceptionally cavity-resistant teeth.)
Why it works: The protective outer layer of tooth enamel is made of hydroxyapatite. That starts to break down when it comes into contact with the sugar you eat and the bacteria in plaque that convert the sugar to acid. And that leads to tooth decay. Fluoride helps remineralize the tooth. “It forms what dentists call fluoridated hydroxyapatite. That is much more resistant to the acid,” says Howard Pollick, BDS, a former spokesperson on fluoridation for the American Dental Association. Fluoride is the only substance that’s been shown to do this. The mineral also occurs in trace amounts in many foods (oatmeal, potatoes), and, of course, in fluoridated toothpaste and mouthwash.
What It Does for Your Teeth
THE CENTERS FOR Disease Control and Prevention (CDC) calls fluoridated water “one of the greatest public health achievements of the 20th century.” Cavities are a bigger problem than you might think. In 1941, explains Carstairs, men had to have six opposing teeth to join the armed services. Almost 10 percent of recruits didn’t—making teeth the number one reason men were rejected. Add to that a shortage of dentists, and a large-scale solution started to look appealing.
“Fluoridated water not only reduces cavities by 25 percent in children and adults but has also contributed to decreasing pain, discomfort, and missed school/work,” explains Anthony J. Santella, DrPH, MPH, a professor of public health at Fairfield University. “Additionally, the science is clear: Poor oral health is linked to poor overall health, particularly with increased incidence of diabetes, heart disease, and pregnancy complications, to name a few.” He also points out that water fluoridation is “cost-effective and promotes health equity.”
Key dentist, physician, and public health groups, including the American Dental Association, the American Academy of Pediatrics, and the American Public Health Association, all support its use.
What About the Rest of Your Body?
BECAUSE FLUORIDE CAN stimulate new bone growth, researchers have looked at whether fluoride helps reduce bone fracture risk, but their findings are inconclusive. The CDC says that studies in peer-reviewed journals haven’t found evidence of links between water fluoridation and increased risks of cancer, Down syndrome, heart disease, osteoporosis, bone fractures, immune disorders, low intelligence, renal disorders, Alzheimer’s disease, or allergic reactions.
A 2024 National Toxicology Program monograph delved into research about fluoride and our brains. It didn’t express much confidence that “fluoride exposure is associated with adverse effects on adult cognition.” However, it had “moderate confidence” in findings that higher fluoride exposures “are consistently associated with lower IQ in children.” Its bottom line: More research is needed.
Holes in research tend to invite speculation, worry, and social media posts. The scientific process, in which evidence evolves and bottom lines change, can feel confusing. This creates an opportunity to promote doubt and mistrust in a field in which results just take a while. It’s hard to wait for answers but also not helpful to make them up.
“There is something about WATER and the NECESSITY of it for OUR LIVES that makes people particularly PROTECTIVE of the water supply.”
“Determining exactly what the consequences of small amounts of fluoride in the water are is a very difficult scientific question to answer,” says Carstairs. The decision to fluoridate water is up to the state or the community; it’s not CDC-mandated nor federally controlled. The U.S. Public Health Service recommends an optimal fluoride concentration of 0.7 milligrams per liter of water. It would take a lot more—about 5 milligrams of fluoride per kilogram of body weight (for a 165-pound person, that’s 375 milligrams)—to “cause serious systemic toxicity,” according to estimates cited by the National Institutes of Health. “The health risks associated with water fluoridation are related to studies with fluoride levels well above what’s used in most public health programs,” explains Santella.
What Happens if You Don’t Get Fluoride
ADULTS WITH HEALTHY teeth who suddenly stop using fluoride toothpaste likely won’t see any problems right away, says Kenneth Markowitz, DDS, an associate professor of oral biology and restorative dentistry at the Rutgers School of Dental Medicine. It can take years for tooth decay and cavities to develop.
If you don’t live in an area with water fluoridation, brushing with fluoride toothpaste is usually sufficient, says Cheryline Pezzullo, DDS, at the NYU College of Dentistry. It’s tempting to think that toothpastes containing hydroxyapatite—the stuff teeth are made of—might make a good fluoride-free alternative. But Dr. Markowitz says there’s little evidence to suggest that applying it that way can prevent tooth decay.
If you’re prone to cavities, you can consider using a fluoride mouth rinse. Dentists can also prescribe toothpaste with a higher amount of fluoride or apply a fluoride varnish or gel. People with gum disease or a dry mouth caused by health conditions or medications might also need extra fluoride, Dr. Markowitz says.
If you choose to use fluoride-free toothpaste and don’t have fluoride in the water, you would need to “restrict your sugar intake severely,” Dr. Pollick adds. That includes limiting beer, wine, fruit, and sweets. That’s a pretty high bar, and there’s this too: You also need to brush twice a day, floss, and see your dentist regularly.
