A growing body of evidence promises that beet juice can improve athletic performance while it lowers blood pressure. But how much to drink? According to new research, about two shots before a high-intensity workout will do it. In a recent study, sports scientist Lee Wylie at the University of Exeter observed athletes taking concentrated beet juice, produced by the U.K. company Beet-It. (The concentrated version is easier to digest.) In the study, he found that the highest dose he gave the athletes (280 ml) created the most efficient oxygen consumption in the workout – lowering intake by about 3 percent over the course of a moderate cycling workout. Beet juice helps performance because it’s loaded with nitrates, which the body converts into nitric oxide, a gas that widens blood vessels, bringing more oxygen to muscles during endurance activities like running, swimming, and cycling. “If you’re working out at high intensity,” says Wylie, “about 140 ml of concentrated juice two to two and a half hours beforehand is ideal.” If working out at lower intensity, then a larger dose of 210 ml to 280 ml consumed three hours prior to exercise should produce the best results.