High fructose corn syrup (HFCS) is a clear liquid that is mostly fructose and glucose. It was developed by Richard Marshalle and Earl Kooi in 1957. In the 1970's it was introduced to the food and drink industry as a cheaper alternative to table sugar. It is slightly cheaper in the US because of corn subsidies and sugar tariffs/quotas. Easier to transport because it's liquid and sweeter than table sugar. Between 1970 and 1990, our consumption of HFCS increased 1000%.

High fructose corn syrup is created by milling corn to produce corn starch. It is then processed to yield corn syrup. Corn syrup is almost entirely glucose. Enzymes are used to change glucose into fructose. The result is 42-55% fructose, with the rest glucose and higher sugars. Fructose in itself isn't a bad thing as most fruits have this form of sugar. But HFCS is a processed sugar that quickly metabolizes in the liver increasing fat storage. Glucose metabolism is disturbed leading to metabolic disturbances. These metabolic disturbances create insulin resistance in the body.

Excess fructose intake has been associated with adverse health effects such as metabolic syndrome, elevated triglyceride levels, hypertension, non-alcoholic fatty liver disease, excess uric acid levels (associated with gout), and elevated levels of advanced glycation end products (AGEs; linked with aging and complications of diabetes).