Carnitine, chromium, anabolic steroids: Athletes have experimented with a broad array of aids in pursuit of a performance edge. A popular — if unglamorous — one today that seems safe and backed by solid data: the juice of beets, for the nitrate it contains.

Inorganic nitrate (NO3-) is added to cured and processed meats to extend their shelf life and give them their distinctive pink color. It’s also naturally found in spinach, arugula and beets. In the past decade, new evidence has sug