“Know what they always find in Alzheimer’s patients? Excessive aluminum in the brain. Know what makes your body hoard aluminum? Fluoride.”

A favorite boogeyman — fluoride — is at the center of social media claims that it can contribute to Alzheimer’s disease.

“Know what they always find in Alzheimer’s patients?” asks a July 26 post on Facebook. “Excessive aluminum in the brain. Know what makes your body hoard aluminum? Fluoride.”

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

But evidence does not support the claim that aluminum is increased in the brains of people with Alzheimer’s disease, or that aluminum is a cause of the disease, according to Alzheimer’s organizations. And fluoride that’s added to drinking water and toothpaste is safe and beneficial.

The idea that Alzheimer’s and aluminum might be linked first came to light in 1965, when “researchers found that rabbits injected with an extremely high dose of aluminum developed toxic tau tangles in their brains,” according to Alzheimer’s Society, a United Kingdom nonprofit. (Tau tangles are large accumulations of microscopic brain protein fragments that slow someone’s ability to think and remember.)

However, the result occurred only when the rabbits had extremely high exposures to aluminum that “far exceed the levels that can enter the body” through food or everyday sources such as aluminum cookware.

Since then, despite continuing research, “there is no solid evidence that aluminum is increased in the brains of people with Alzheimer’s disease,” the society reported. “No convincing relationship between (the) amount of exposure or aluminum in the body and the development of Alzheimer’s disease has been established.”

Other Alzheimer’s groups in the U.S., such as the Alzheimer’s Association and Bright Focus Foundation, concur, with the former noting, “Studies have failed to confirm any role for aluminum in causing Alzheimer’s.”

Fluoride, meanwhile, is considered safe in both drinking water and toothpaste, which are the main ways people consume it.

Our ruling

A Facebook post says, “Know what they always find in Alzheimer’s patients? Excessive aluminum in the brain. Know what makes your body hoard aluminum? Fluoride.”

However, evidence does not support the claim that aluminum is increased in the brains of people with Alzheimer’s disease, or that aluminum is a cause of the disease.

And fluoride is considered safe in both drinking water and toothpaste, which are the main ways people consume it.

We rate this claim False.