WASHINGTON — On Friday, the Food and Drug Administration (FDA) announced new restrictions on the use of fluoride supplements designed to fortify children’s teeth. This decision marks the latest initiative by Health Secretary Robert F. Kennedy Jr. and his team to scrutinize a chemical traditionally integral to dental care.

The FDA now advises against prescribing these supplements to children under the age of 3, as well as to older children who are not at significant risk of developing tooth decay. Previously, these supplements were recommended for children as young as six months old.

While the FDA had indicated in May that it might pursue a complete market withdrawal of these products, the agency has instead issued warnings to four companies, instructing them to adhere to the newly established guidelines for their products.

Fluoride tablets and lozenges have been recommended for children and adolescents who are at an elevated risk of cavities due to insufficient fluoride levels in their local water supply. Additionally, some companies offer fluoride drops specifically formulated for infants.

Accompanying Friday’s announcement, the FDA released a fresh scientific evaluation indicating that fluoride supplements offer limited dental benefits for children. The evaluation also raised concerns about potential safety issues, such as digestive problems, weight gain, and cognitive effects.

“The antibacterial properties of fluoride on teeth might also disrupt the gut microbiome, potentially leading to broader health issues,” the FDA stated in a press release.

The agency also sent a form letter to dentists and other health providers warning about the risks of the products.

Those claims have been disputed by the American Dental Association, which has said there are no significant health problems associated with fluoride when used at the levels prescribed by dentists. The supplements can cause spotting or discoloration of teeth due to the extra fluoride, a downside the FDA also noted.

Dentists have warned that restricting fluoride supplements may result in more cavities and dental problems in rural communities, which are less likely to have fluoridated water. Kennedy is also seeking to end the practice of adding fluoride to drinking water throughout the U.S.

Fluoride strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear, according to the Centers for Disease Control and Prevention. In 1962, the agency set guidelines for how much should be added to water.

Kennedy, a former environmental lawyer, has called fluoride a “dangerous neurotoxin” tied to a range of health dangers.

The FDA regulates most dental products, including fluoride-containing toothpastes, supplements, mouthwashes and rinses. The agency’s actions don’t affect toothpastes, mouthwash or fluoride treatments used by adults or those offered in dentists’ offices.

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