Young girls who get extra calcium from food tend to gain more bone mass than those who get it from tablet supplements, but children who already receive adequate amounts of calcium in their diets do not benefit from any form of extra calcium, a research team in Finland reports.
"We conducted the study to learn how to maximize the children’s peak bone mass during the rapid-growth period of puberty — in which 60 percent of the adult bone mass accumulates — and thus prevent osteoporosis in adulthood," Dr. Sulin Cheng from the University of Jyväskylä in Finland told Reuters Health.
For two years, Cheng and her colleagues followed a group of 195 healthy girls, ages 10 to 12, whose calcium intake was under the National Nutrition Council recommended levels (less than 900 mg a day.) They randomly assigned the children to receive 1000 mg calcium tablets, 1000 mg calcium plus 200 IU vitamin D tablets, low-fat cheese (1000 mg of calcium), or placebo tablets.
The researchers measured the effects of calcium supplementation on bone mass and body composition, and analyzed the data using traditional statistics as well as a new model that takes into account the rate of body growth.
"We found that the cheese group showed more beneficial effects in their bones than any of the other groups," said Cheng, "but when we took into account the individual growth speed, we found no beneficial effect with any of the interventions — calcium alone, calcium plus vitamin D, or even cheese supplementation. This means that if you exceed certain levels of your dietary calcium intake, it doesn’t matter how much you take; you won’t get any benefits," explained Cheng.
In the Finish study, most subjects were already receiving adequate levels of calcium in their diets. Only one percent of the girls in the total screened population (more than 1000 girls) had a dietary calcium intake below 400 mg/day. "In Nordic countries, people already get enough calcium," added Cheng.
The authors believe that their study brings up a very important question for the entire medical community: how to avoid the unnecessary calcium supplementation in normally growing children. "I hope these results will make doctors and authorities think about this issue," said Cheng.
SOURCE: American Journal of Clinical Nutrition, November 2005.
