Children, who take calcium supplements to improve their bone mineral density, do not benefit from it, as they are unlikely to prevent broken bones. Calcium is found in many foods and it is thought that taking supplements can help build stronger bones in children, which could reduce the risk of osteoporosis, or brittle bone disease, later in life. Researchers from the Menzies Research Institute in Tasmania analysed 19 studies involving nearly 3,000 children and found that youngsters taking the supplements showed a small increase in bone mineral density in the arms but not at the hip or lower spine. This small increase in upper limb bone mineral density is unlikely to result in a clinically important decrease in the risk of fracture. How much bone is built up during childhood and lost as an adult determines the likelihood of developing osteoporosis. At least 90 percent of peak bone mass is obtained by the age of 18. In the current study, children aged 3-18 years, were given calcium supplements or a dummy pill for periods ranging from 8.5 months to 7 years. Researchers then measured the strength of the children's bones with density tests using overall body measurements at the hip, spine and arm. They found the amount of increase was the same in the hip and spine in both groups of children and only slightly better in the arm in the supplement group. The results were the same regardless of the child's sex, ethnic background, exercise level or age. The small effect of calcium supplementation on bone mineral density in the upper limb is unlikely to reduce the risk of fracture, either in childhood or later life. The researchers therefore called for more research and said that other measures, such as eating more fruit and vegetables and increasing vitamin D concentrations, should be explored.
British Medical Journal,
September 2006