"Most of the fructose we have comes from high-fructose corn syrup and table sugar and added sugar, which are made of glucose and fructose," Richard Johnson, a professor of medicine at the University of Colorado Anschutz Medical Campus, told Newsweek. "Soft drinks can have as much as 30 grams of fructose in them, while a kiwi may have just 2 to 3 grams."