C a l c i u m
Is needed for muscle, heart and digestive system health, builds bone, supports synthesis and function of blood cells, as well as activation of enzymes.
Most of the calcium from food goes straight to the teeth and bones, where it is used for building and maintaining strength (also muscle contraction).
Calcium is also used throughout the body to help muscles contract, enable blood to clot, transmit messages along nerves, produce energy, keep the heart beating, and maintain the immune system.
1300 mg RDA - 2500 mg UL
RDA (recommanded dietary allowances) per day 
UL (tolerable upper intake level) per day 
 Food and Drug Administration (FDA)
 Dietary Reference Intakes: Tolerable Upper Intake Levels, Food and Nutrition Board, Institute of Medicine, National Academies, 1997