In one of Lustig's videos he talks about fructose from fruit juice. He says if you want fruit juice, eat fruit. The problem comes when you drink a glass of apple juice. That's the juice from about 8 apples. Now, instead of the juice, try eating 8 apples. It's just not really something someone's going to do, it's so much work to grind through all that food. But a glass of apple juice is easy.