caffeine是什么意思？

Caffeine, a substance found in coffee and some soft drinks, is also a drug.

The caffeine—the equivalent of two strong cups of coffee, was sufficient to reverse this effect, with some cyclists even displaying increased eye movement speeds.

To find out, researchers gave 11 volunteer cyclists a carbohydrate solution either with a moderate dose of caffeine,  which is known to stimulate the central nervous system, or as a placebo without, during 3 hours of cycling.

In West Africa, people have long chewed kola nuts as stimulants, because they contain caffeine that also occurs naturally in tea, coffee, and chocolate.

So there could be less protein, more sugar and some additives you wouldn't expect, such as caffeine.