Man walks through a Walmart toothpaste aisle claiming nearly every brand is unsafe. Then he read the labels one by one

A man who posts on TikTok as Zach Iroz (@theoriginalzachiroz) said in a video that he was standing in a Walmart toothpaste aisle for what he called a field test. The clip has drawn about 6.1 million views, 912,900 likes, and more than 3,600 comments.

Iroz said most people do not know that teeth can fill cavities again through a process he called remineralization, if nutrition is good enough. He then asked what stops that process and answered his own question. “Glycerin. Glycerin does that,” he said.

He picked up boxes one by one and read ingredient lists on camera. He pointed to glycerin on Crest + Scope, Sensodyne Sensitive, Arm & Hammer, Colgate, Boka, Hello, Tom’s of Maine, and Listerine Essential Care. He said Aim Cavity Protection did not list glycerin but did list fluoride, “which calcifies the pineal gland.”

Dentists say the glycerin film claim comes from a 1997 book with no published experiment

Iroz said Close-Up Cinnamon Blast had Red 33 and Red 40 and sodium fluoride. “That pretty much exhausts all the toothpastes here at Walmart,” he said. “So, you know, the next time you go to buy your toothpaste, maybe don’t look in the big box stores.” Skepticism about big-box store products can extend beyond toothpaste, as one man’s price check on Reese’s in Walmart led him to boycott Halloween candy. 

Dr. Jennifer Eisenhuth, who writes as Dr. Jen, said glycerin is a humectant used to keep toothpaste from drying out in the tube. She said it mixes completely with water, so rinsing removes it. 

She wrote that the claim that a film blocks mineral traces dates back to a 1997 self-published book by retired chemistry professor Gerard Judd, with no journal paper or measurement to support the idea.

Eisenhuth said a 2023 Frontiers in Public Health trial compared a 10% hydroxyapatite toothpaste with 1,450 ppm sodium fluoride in 194 adults over 18 months. Mean DMFS increment was 0.02 in the hydroxyapatite group, 0.31 in the fluoride group, and 89.3% of the hydroxyapatite group showed no increase. 

Glycerin was the third ingredient in the hydroxyapatite paste. She said that the result would be hard to explain if glycerin sealed enamel against mineral uptake. She added that the trial is an inference, not a study designed only to test a glycerin film, and that glycerin is in the formula for texture and shelf life, not as an enamel treatment.

And according to Dr. Kami Hoss, current scientific evidence does not support the idea that glycerin harms enamel or blocks remineralization. He said glycerin is generally recognized as safe for oral use and has long been used to retain moisture and improve texture. He said there is no reputable evidence that it blocks fluoride or hydroxyapatite. Because glycerin is water-soluble, he wrote, saliva and the minerals it carries can still reach the tooth.

Hoss said glycerin has not been shown to be toxic for most people and that reactions, when they occur, usually involve the whole formula rather than glycerin alone. He said what matters more is the active ingredient, abrasiveness, pH, and overall formulation. 

Commenters on Iroz’s video offered mixed reactions. One wrote, “that’s why I don’t brush my teeth.” Another said, “I use Japanese toothpaste now and my teeth stopped hurting randomly and being sensitive to cold foods and drinks.” 

A third wrote, “Baking soda and salt. the old stand by.” One commenter said, “the solution is to just not have cavities.” Another wrote, “we genuinely need to research everything we see on social media before believing it.”