Cane sugar, Zenker explained, is nearly 100% sucrose, which consists of approximately 50% glucose and 50% fructose — two different forms of sugars. It's "essentially the same as table sugar," she said. The most common form of high-fructose corn syrup contains 55% fructose and 45% glucose.

Coca-Cola has used corn syrup to sweeten most of its U.S. products since 1980 to reduce production costs against rising sugar prices. The syrup is also more shelf stable than regular sugar.

In much of the world, Coke is made with cane sugar. The majority of Coke sold in the United States is made with corn syrup, a far cheaper alternative used since a switch in the 1980s.