Cobalt’s story runs from troublesome “goblin ore” and brilliant blue pigments to the single metal atom at the center of vitamin B12. Here is what runners need to know about B12, food sources, supplementation, and why cobalt salts are a dangerous wrong turn.

Molybdenum spent centuries mistaken for graphite and lead ore before chemists uncovered element 42. Here is what this essential trace mineral does, where runners get it, and why biological necessity is not the same as a performance benefit.