Define about Calcium and Osteoporosis?
Gain in bone mass occurs throughout childhood; however, during adolescent growth spurt, the gain in bone mass, as well as, calcium retention is accelerated two to three times more than at younger ages in both boys and girls, The bone mineral content continues to increase beyond the growth spurt into the middle of .the third decade. Progressive increase in total body calcium have been shown in one study upto 30 years in female subjects of 19-30 years on an average calcium intake of 700 mg per day. Thus, peak bone mass may be achieved 5-10 years after longitudinal bone growth has been completed. Achievement of adult height is an indication of completion of longitudinal growth. There is some data to show that increased calcium intakes in children beyond their habitual intakes could increase bone mineral density. What needs to be established is whether such increase in bone density could contribute to increased peak bone mass (i.e. maximum bone mass attained by the middle third decade).
The other factor of importance contributing to increased bone mineral density and peak bone mass is weight bearing exercise. The current recommendations in fact focus on adequate dietary calcium intakes and exercise to promote acquisition of peak bone mass and density fracture risks due to osteoporosis at later ages can be reduced. Accelerated bone loss with age is a consistent finding in both women and men. It occurs earlier in women than in men as decreased oestrogen production in menopause is associated with accelerated bone loss in women, estimated at 3% per year in the first five years after menopause. The effectiveness of calcium supplements in retarding bone loss in post menopausal women is not entirely settled. However, clinical trials in this area seem to indicate that supplements of calcium can have beneficial effect in slowing the rate of bone loss in post menopausal women.
The amounts recommended by different advisory groups differ considerably. It seems prudent to recommend that women with calcium intakes below 400 mg per day may benefit by increasing their dietary intakes or by taking supplements of calcium. This is supported by a study on two groups of post menopausal women, one with usual intakes less than 400 mg per day and the other with usual intakes between 400-650 mg per day. Calcium supplementation benefited the group with intakes less than 400 mg per day by slowing the rate of bone loss at several sites while supplements were not effective for the group with intakes between 400-650 mg per day. The role of appropriate exercise, in addition to adequate calcium intake, must receive proper attention. The other nutrient in relation to calcium absorption and bone mineral density is vitamin D. It must however, be emphasized here that vitamin D nutrition is as important as that of calcium in relation to prevention of osteoporosis and fractures. An important aspect that we shall discuss now is the relationship of calcium with blood pressure and what is the significance of calcium deficiency with respect to hypertension.