Vanadium is a micromineral found in trace amounts within the body and the diet. Food sources most rich in vanadium include spinach, shellfish, black pepper, mushrooms, and parsley. Vanadium has not been established as an essential nutrient; however, it has been demonstrated to have functions similar to those of insulin in humans with non-insulin-dependent diabetes mellitus. Those effects include decreased blood glucose concentrations during fasting, increased insulin-mediated glucose uptake, and increased muscle glycogen synthesis. Since insulin is an important anabolic hormone and vanadium may produce similar effects in diabetic subjects, vanadium, particularly as vanadyl sulfate, has been marketed for its potential to increase lean body mass and strength in athletes as well as optimize glycogen stores.