Calcium is used to prevent or treat low blood calcium levels in people who do not get enough calcium from their diets. Calcium is important for growth and development of bones.
Vitamin D3(cholecalciferol) that is used in the absorption of calcium in the blood. Vitamin D3 helps in processing of essential minerals in the body like Calcium and Phosphorus. Lack of Vitamin D3 results in bone weakening, bone pain, and skin diseases.

Zecal is a nutritional supplement which can be taken by people who have low levels of calcium in their blood.
Zecal is used in elderly people to keep bones healthy and strong, and is even effective in Chronic arthritis and Osteoporosis.

Caution:
Use under medical supervision.