Calcium is the most plentiful mineral found in the human body, accounting for 1.5% to 2% of an adult's total body weight. The teeth and the bones contain the majority of the body's calcium (about 99%).

'Elderly persons are at increased risk for calcium and vitamin D insufficiency. There are also several alterations in body functions that can contribute to calcium loss from bone, and hence increased risk of osteoporosis.

With ageing there is:
A decrease in dietary calcium intake,
         usually as a result of decreased overall dietary energy intake
        (e.g. poorer appetite, illnesses, social and economic factors)
A decrease in the intestinal absorption of calcium
        (exacerbated if vitamin D status is low)
A decrease in the capacity of the intestinal cells to adapt
        to a low calcium intake, and increase their absorptive capacity
        Less frequent exposure to sunlight
        (e.g. elderly who are housebound, or institutionalized, or have reduced mobility)
         hence poorer vitamin D status
A decrease in the capacity of the skin to synthesize vitamin D
A decrease in the efficiency with which the kidneys
        can retain calcium, leading to increased calcium loss
        in the urine
A decrease in the capacity of the kidneys to convert
         vitamin D into the most active form,
         1,25-dihydroxyvitamin D'

     (Source: International Osteoporosis Foundation)

Calcium has other functions in addition to maintaining healthy teeth and bones. Blood coagulation, transmission of nerve impulses, muscle contraction and relaxation, normal heartbeat, stimulation of hormone secretion, activation of enzyme reactions, as well as other functions all require small amounts of calcium.

Recommended Calcium & Vitamin D Intake