Calcium paradox: Consequences of calcium deficiency manifested by a wide variety of diseases

Calcium deficiency is a global problem, especially in the aging population. Among various nutrients, calcium is one of the few that is still deficient in industrialized countries such as Japan and many Western countries. Calcium deficiency is readily connected with osteoporosis, which is a decrease of bone calcium content. Less well known is the calcium outflow from bone that occurs to prevent decrease of blood calcium in calcium deficiency caused by the parathyroid hormone, with consequent calcium overflow into soft tissues and the intracellular compartment. Such intracellular paradoxical Ca overload as a consequence of nutritional calcium deficiency may give rise to a number of diseases common in old age: hypertension, arteriosclerosis, diabetes mellitus, neurodegenerative diseases, malignancy, and degenerative joint disease.