The single most important ingredient of high-performance sports drinks

I have an article in the current issue of National Geographic about the sense of taste. While I was researching it, Michael Tordoff, a scientist at the Monell Chemical Senses Center, in Philadelphia, handed me a plastic medicine cup containing a clear liquid and asked me to drink it. It tasted like water.

Tordoff said, "You didn't taste much of anything, but this is something that rats and mice prefer to almost everything else we have ever, ever tested." The liquid contained maltodextrin, a kind of starch. If an athlete takes a mouthful of maltodextrin solution and immediately spits it out, he said, the athlete will perform better, despite having tasted and ingested nothing, or next to nothing. "I don't have a good explanation," he continued. "There's something very special about starch that we don't understand."

Some sports drinks contain maltodextrin, but that's not the ingredient I mean. The ingredient I mean is mildly yucky taste. In foods and beverages that are supposed to be good for you, deliciousness is usually a liability, because people tend to believe that if something tastes good it can’t possibly be beneficial. Several years ago, Mattson, a food-and-development firm in California, was hired by a physician who wanted to develop a supplement containing glucosamine and chondroitin, which some people believe relieve the symptoms of arthritis.

Barb Stuckey -- who is Mattson's chief innovation officer and the author of a good book called Taste -- told me, “We talked him out of a bar and into a beverage, because in a beverage you can control the calorie count better.”

Shrinking the portion to “shot size” was a challenge, though, because glucosamine is extremely sour, and chondroitin is salty and has what Stuckey described as a “barnyard-y” smell. To help mask the off tastes, Mattson’s technicians added stevia, a non-nutritive sweetener derived from a plant, and because stevia has a “tail” -- a lingering aftertaste -- they added a small amount of sugar, which cuts it.

They found that “citrus” was better than “berry” at disguising the tastes they were trying to disguise, and that giving the beverage a slightly silky mouthfeel reinforced the idea that it was coating sore joints. But they didn’t make it taste too good. The model there, Stuckey told me, was the popular energy drink Red Bull -- which, she said, was purposely given “just the right amount of bad.”