What’s good? What’s bad? How much sugar is too much? Here’s what the latest science says.
"There is no substitute for whole natural foods, a variety of foods, eaten in season. I read that xylitol, which is marketed as a natural sugar, is actually processed using toxic chemicals. "
Are We Overdosing?
Luckily for Lustig, Kimber Stanhope, Ph.D., and Peter Havel, D.V.M, Ph.D., have been busily conducting trials in their labs at the University of California, Davis. In one of their studies, overweight or obese people who spent 10 weeks drinking 25 percent of their calories from fructose drinks (versus a group drinking glucose) increased their post-meal triglycerides (a risk factor for heart disease) and decreased insulin sensitivity (a risk factor for type 2 diabetes).
Interestingly, they also found that drinking fructose caused the subjects to gain visceral fat, the kind of fat in the belly that’s associated with metabolic syndrome; drinking glucose added fat, too, but here the fat was subcutaneous, the “safe” kind that has no established relationship with disease. Drinking fructose also enhanced the body’s ability to convert carbohydrate into fat in the liver, which causes insulin resistance and type 2 diabetes.
Stanhope is in the middle of another big new trial in which, instead of giving subjects pure fructose (something no one drinks in the real world) as she has in earlier studies, she is giving folks what they can buy from convenience stores and vending machines: HFCS-sweetened drinks. She’s also studying young, healthy people instead of obese people. The trial’s first results (there’s more to come) were just published and they, too, seem to support Lustig’s theory: triglycerides and “bad” LDL cholesterol increased only in subjects who drank the fructose or HFCS, not glucose.
Still, the fructose doses used in most of Stanhope’s studies are higher than most humans would normally consume. There’s “no unequivocal evidence that fructose intake at moderate doses is directly related with adverse metabolic effects,” said Luc Tappy, M.D., professor of physiology at the University of Lausanne and one of the world’s premier fructose researchers, in a review. But Lustig thinks the higher doses in many of these trials just speeds up the inevitable. “It’s completely dosage dependent. A little is fine. A lot is not. And that’s true of every poison,” says Lustig.