Cobalt is a trace element, a metal, that is part of vitamin B-12 and plays an important role in maintaining normal human health, according to Michael Meguid, MD, a professor emeritus from Upstate who is the emeritus eidtor-in-chief of "Nutrition, The International Journal of Applied and Basic Nutritional Sciences." Meguid, a surgeon who became interested in nutrition, explains the role of cobalt and what happens if there is too much or too little in the body.