In this hour You Tube lecture Robert Lustig explains the biochemistry that explains why fructose is dangerous.
Sugar: The Bitter Truth
You may also want to read the very latest science on the subject.
Soft drink consumption and obesity: it is all about fructose.
"The present review concludes on the basis of the data assembled here that in the amounts currently consumed, fructose is hazardous to the cardiometabolic health of many children, adolescents and adults."
For those keen on understanding the science in more detail Potential role of sugar (fructose) in the epidemic of hypertension, obesity and the metabolic syndrome, diabetes, kidney disease, and cardiovascular disease Johnson RJ is the author of the book The Sugar Fix.