by Marion Nestle
Aug 10 2007

Sugars: Fructose v. Glucose v. Sucrose

Today’s question: “From what I’ve read about high fructose corn syrup, the bad-for-you part about it (in addition to the high quantities people consume at once, like in a 20 oz coke) is the fructose. Is fructose the real evil, and if so, then aren’t foods like fruit juices bad as well?”

Today’s answer: I deal with this vexing question in the Sugar(s) chapter of What to Eat. The problems (and I’m not convinced they are very serious) of fructose depend on what you compare it to. Sucrose, the white stuff in sugar bowls, is a double sugar made of glucose and fructose, 50% each. Corn sweeteners are also glucose (42%) and fructose (55%). I’m not convinced the body can tell them apart. Fruit juices also have glucose and fructose. If you compare the metabolism of fructose to glucose, there are differences, but I think the problems are with quantity, not quality. A little sugar makes foods taste good; a lot adds calories that nobody needs these days. From the standpoint of calories, fruit juice has just as many as soft drinks so a little goes a long way even though it is a healthier alternative.