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. The normal diet contains adequate amounts of vitamin A, and therefore supplements rarely need to be administered. Vitamin A has many important functions in the body that relate to membrane integrity, especially of epithelial cells and mucous membranes. It is also essential for bone growth, reproduction, and embryonic development. Vitamin A deficiency has long been known to result in night blindness, in which the ability of the eye to see in dim light is impaired.