Microamounts of such elements as boron, chromium, chlorine, copper, manganese, molybdenum, selenium, silicon, sulfur, and vanadium are considered necessary to health. Copper deficiency, for example, has been linked with heart disease, and the onset of diabetes in older age may in some way be associated with chromium deficiency. Normal diets appear to provide adequate amounts of trace minerals, but effects such as the linking of high levels of fructose in the diet with copper-deficiency problems are the subject of ongoing research. Magnesium is an essential element in human metabolism and functions in the activities of muscles and nerves, protein synthesis, and many other reactions. Magnesium deficiency may occur in alcoholism, diabetes mellitus, pancreatitis, and renal diseases.
Prolonged deficiency can cause changes in heart and skeletal muscle.
Excessive retention of magnesium can occur in renal disease and results in muscle weakness and hypertension. Vitamin D primarily regulates calcium metabolism by determining the movement of calcium from intestines to blood and from blood to bone. Thus vitamin D is today more legitimately considered a hormone rather than a vitamin. In tropical countries, where exposure to sunlight is high, vitamin D deficiency is rare. It is much more common in northern regions.