Calcium is essential for life and health from birth to old age. It plays key roles in bone and teeth development, muscle function, blood clotting, and nerve signaling. Most calcium in the body is stored in bones and teeth. Calcium deficiency can cause over 100 diseases and symptoms vary by age. The document recommends daily calcium intake amounts and lists those who may need supplements. It describes different calcium supplement types and highlights the advantages of TIENS' amino acid chelated calcium supplements which have high absorption rates and no side effects.