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) that 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 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 placebo 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 baseline. 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 baseline 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.