The warnings are stern: avoid fructose, especially in the form of high-fructose corn syrup, because it’s contributing to an obesity epidemic. And the evidence is strong that people who are sedentary should avoid it. But for active individuals, it’s a different story. “All athletes who compete or train for a period longer than 45 to 60 minutes will improve their performance by ingesting a solution containing carbohydrates,” or sugar, says Luc van Loon, a professor in the Department of Human Movement Sciences at Maastricht University Medical Centre in the Netherlands. And you’ll get more performance bang if that sugar is, in part, fructose. When cyclists in a British study drank a beverage containing both fructose and glucose (a simple sugar that typically appears on labels as maltodextrin), they rode almost 8 percent faster during a time trial than riders who drank fluids with glucose alone. “Fructose and glucose are taken up in the intestine by different transport proteins,” van Loon says. “This allows for a more rapid uptake of carbohydrates from the gut.” Which means you have more calories available to you more quickly if you drink or eat carbohydrates containing fructose.
Most high-fructose corn syrup contains approximately equal portions of glucose and fructose and is perfectly acceptable for athletes. The concerns about high-fructose corn syrup have more to do with the highly processed foods they often show up in rather than the intrinsic characteristics of the sugar. The drawback for endurance athletes is that the ideal ratio of glucose to fructose is 2:1 (not the 1:1 of corn syrups). “There are very few drinks on the market that provide that perfect mix,” says Asker Jeukendrup, a professor of exercise metabolism at the University of Birmingham in England, who led the study of cyclists.
Get over it: Read labels. Some drinks, such as PowerBar’s Ironman Performance beverages, tout their 2:1 glucose-fructose mix. For do-it-yourselfers, sports nutritionist Nancy Clark’s homemade sports drink, from the fourth edition of her Sports Nutrition Guidebook, is an ideal performance boost. Gather together these ingredients:
1/4 cup sugar
1/4 teaspoon salt
1/4 cup orange juice
2 tablespoons lemon juice
Then, in a quart pitcher, dissolve the sugar and salt in ¼ cup hot water. Add the orange and lemon juice and 3½ cups cold water.