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Calcium Supplementation and Increases in Bone Mineral Density in Children
Scientists have found that peak bone mass in childhood is a major cause of bone mineral
density in adulthood and may decrease the risk of osteoporotic fractures. Osteoporotic
fractures are those caused by a disease (Osteoporosis) which causes bones to be extremely
porous. There are however other factors, such as Genetic and Environmental, that play a
major role in determining peak bone mass. Studies done have implied that milk drinking
may help in determining peak bone mass. Since milk is a complex food, other factors, not
just the calcium, may be responsible for the increase in bone mass. Teenaged girls were
studied, and scientists found that an increase in either milk drinking or calcium
supplements was positively proportional to the rate of gain in bone mineral density.
Is calcium alone an effective tool in increasing the rate of change in bone mineral
density in children?
A three year, double blinded, placebo controlled study was done on 70 pairs of identical
twins whose ages ranged from 6 to 14 years old. Of the 70 pairs, only 45 completed the
study. A double blinded study is a study where neither the scientists nor the subjects
know who will receive the plasibo or the calcium supplement. All the monozygotic twins
completed the three-day food records that the scientists instructed them to do on their
initial visit with the families. The food records showed that twenty-two twin pairs were
prepubertal throughout the study, nineteen pairs underwent puberty during the study and
four other were postpubertal at base line. After the measurement of height, weight, and
bone mass from the radius, spine, and hip, a twin from each pair was randomly assigned to
take 1000mg of calcium citrate malate which has been shown to be well absorbed in
children and young adults. The other twin received the placebo. Calcium and creatine were
also measured for safety reasons. All the twins received four 250mg tablets daily and
their activities were monitored. After the intervals of six months, one, and two years
the radial bone mass was measured. After the third year, bone mass's were measured in the
radial, spine and hip. 
The boy's intake of all nutrients was slightly greater and as expected, the girl's
pubertal development was more advanced. The height, weight, and other nutrients had no
significant differences. The base-line bone width, mineral density, and bone mineral
content were similar in the calcium supplement and placebo groups and to those who
drooped out. During the three years, the group who took calcium-supplements received an
average of 1612mg of calcium per day, and the placebo group received 908mg per day. No
consistent changes in bone area or width were observed but bone mineral density increased
by a mean of 1.4 percent in the supplement group. The increases were greater at the
midshaft and distal radius. Prepubertal twins had a greater percent increase in bone
mineral density at all times while postpubertal and those going through puberty had no
significant differences at any time.
In conclusion, only the rate of increase in bone mineral density was positively affected
by the calcium supplementation. The group who received an average of 719mg per day of
calcium supplements had about 3 percent more minerals in the radius than their twins. One
factor that was very significant was sexual maturity. Prepubertal twins had about 4
percent greater increase in bone density while postpubertal and those going through
puberty had little change. To account for these differences, scientists considered dose
sizes and pubertal changes. They believed that pubertal changes such as the secretion of
growth hormones and sex steroids were the main cause for the differences. Bone is either
changing so rapidly or maximally stimulated that small effects of greater calcium intake
can not be detected.