Best and Worst Foods for Sleep MOUNTAIN DEW Worst: Mountain Dew MDX along with jolt Cola and Vault contain 71 milligrams of caffeine per 12-ounce serving. That’s the upper limit of what the U.S. Food and Drug Administration allows. Other sodas aren’t much better. Previous Next 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 2017-09-22 admin Share ! tweet