On that infamous school Coca-Cola experiment

“In the fall of 1950, a Cornell University professor named Clive McCay, a nutritionist, testified in the U.S. House of Representatives that the sugar in Coke caused cavities. He gave a vivid account that instantly became part of folklore — a tooth left in a glass of Coca-Cola would soften and begin to dissolve in a period of two days.”¹

Note that this testimony had nothing to do with nails but with teeth. And it had to do with letting them soak in a glass of Coca-Cola for two days. There were many things wrong with this experiment. First, it gave rise to folklore that it would dissolve a steel nail. People completely forgot that teeth were involved and that nails were not part of the experiment. Second, it overlooked the fact that teeth in human mouths do not remain submerged in Coke. The Coke flows past the teeth, and the teeth are essentially rinsed by the mouth’s saliva. Third, it failed to explain why Coke was any worse than the hundreds of years that human beings in various cultures had been eating spicy, acidic food without their cultures demonstrating a higher rate of caries than cultures that ate bland food (like the English).

The experiment was replicated in 2003.² Note that the person replicating the experiment used both metal nails and shavings of keratin from human nails and claws. The author did not use teeth, but even after multiple days, he was unable to show the dissolving power of Coke in any of the various varieties found in 2003.

Whether the original experiment was ever performed is an intriguing question. Certainly, I saw no evidence that it was successfully replicated, if it had ever been performed. Experimenters have found out that Coke can be used to remove rust from nails, but it is a slow process, and there are better cleaning compounds. Teeth also appear to be basically safe from Coke. Moreover, the experiment makes little theoretical sense. “Under normal physiological conditions, the pH value from the stomach to the intestine basically showed an increasing trend, specifically, acidic stomach (pH 1.5 to 3.5), duodenum (pH 6), terminal ileum (pH 7.4), terminal cecum (pH 6), and colon (pH 6.7).”³ The pH of Coke is around 2.8, well within the pH of the stomach.⁴

It does appear that prolonged use of Coke may help demineralize the enamel of teeth. However, the conclusion of many of the anti-Coke crusaders of yore was that it was the acidic nature of Coke and its sugary content that did the damage. Conveniently, the same crusaders ignored that orange juice is also acidic and sugary. I wonder whether lemonade, which is made from acidic lemons and sugar, is also harmful for your teeth and for metal nails. I suspect that the argument would have been, “Uhm, well, orange juice and lemons are natural, so they could not be harmful.” I express this opinion because I believe it marks the start of many flawed arguments that attempt to conclude that only natural foods are safe.⁵

As for me, a great-grandfather with all my natural teeth in place after years of drinking Coke, I will continue to drink my Coke while sighing at all the natural food people who keep pushing not simply unproven but disproven claims.