Calcium is continually being removed from the bones and returned to the bones - a lifelong process known as remodelling. During pregnancy and lactation it is essential for the mother to ensure she has a good supply of dietary calcium to cover her own needs and those of the growing baby. Eating a healthy diet from a wide variety of foods and participating in moderate weight-bearing exercise through life, assist in calcium absorption. The entire skeleton of a young child is replaced over a period of two years so the demand for calcium is constant for growth and bone maintenance. A healthy lifestyle and healthy eating habits should be developed at a young age.
Teenagers have special needs for calcium to cope with the sudden growth spurt accompanying puberty.
Even when teenagers stop growing in height, around eighteen years of age, girls continue to add calcium to their pelvic bones. During adolescence young women who diet and exercise excessively may stop menstruating, leading to a decrease in hormone levels and subsequent reduction in bone strength. From childhood to around eighteen to twenty years of age there is a great increase in bone strength, especially during adolescence. This is termed peak bone mass, which is the maximum bone strength we can attain. It is therefore important, for men and especially for women, to build up sufficient calcium over the first twenty years, but even after peak bone mass has been attained we still need calcium to maintain strong healthy bones.