The symptoms of thiamine deficiency are known as beriberi, a syndrome consisting primarily of peripheral neuritis marked by sensory and motor paralysis of the limbs and, finally, heart failure. People of Asia who acquired beriberi as a result of a diet of mainly polished rice could be cured by adding rice polishings, which are high in thiamine. Today, thiamine deficiency results from liver damage and most often occurs in nutritionally deficient alcoholics. 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. Calcium promotes bone rigidity and is important in maintaining the integrity of intracellular cement and cellular membranes. It also regulates nervous excitability and muscle contraction and may be protective against high blood pressure. During periods of growth, pregnancy, and lactation, calcium intake should be increased. Diseases of calcium metabolism include vitamin D deficiency, hypervitaminosis D, hypo- and hyperparathyroidism, and some forms of renal disease.