Pharmacology shows that everyday chemicals change the way a body works, and the amount matters. Daphnia are tiny see-through creatures whose hearts beat under a microscope. The higher the energy drink concentration, the faster the heart rate. Daphnia in pure water averaged 190 beats per minute, while those in full-strength Red Bull averaged 268.

Using see-through water fleas to test substances lets you measure the effect on a living body with a simple count. Daphnia placed in increasing amounts of Red Bull show faster heart rates at higher concentrations. Those in full-strength Red Bull averaged 268 beats per minute, compared to 190 in pure water.