Teen-age girls who increase their calcium consumption can drastically reduce their chances of suffering from the brittle-bone disease osteoporosis later in life, experts reported yesterday.
In a new study by Pennsylvania researchers, girls who took calcium supplements starting at age 12 or 14 increased their bone mass by 4 percent by age 16, compared to those who did not take the supplements.
If the higher bone mass persists after the girls reach skeletal maturity -- about age 21 -- these teens could reduce their risk of future osteoporosis-related bone fractures by almost 50 percent, said lead researcher Tom Lloyd, director of the Young Women's Health Study at the Pennsylvania State University College of Medicine in Hershey.
Mr. Lloyd discussed his findings yesterday at a meeting of the American Society for Bone and Mineral Research in Baltimore.
Most people, especially young girls, are deficient in calcium, he said. The 500-milligram supplements given to the girls in the study, when combined with their calcium intake from food, raised their daily calcium consumption to about 1,200 milligrams per day.
Last year, a National Institutes of Health panel recommended that people ages 11 to 24 consume 1,200 to 1,500 milligrams of calcium per day, those between ages 25 and 50 get 1,000 milligrams of calcium a day (the equivalent of about three 8-ounce glasses of milk), and postmenopausal women get 1,500 milligrams per day (the equivalent of five 8-ounce glasses of milk).
In reality, most American women get less than 800 milligrams of calcium per day, according to NIH experts.
When the the recommendations were released, Dr. John Bilezikian, the panel chairman, said that proper calcium intake "is most important from childhood through the mid-20s for achieving peak bone mass, and in later life, to modify the rate of bone loss associated with aging."
More than 25 million Americans suffer from osteoporosis, and the disease causes about 1.5 million bone fractures each year. The disorder is characterized by a decrease in bone mass and a weakening of the bone's inner structure.
Women are more likely than men to suffer from the brittle-bone disease. Postmenopausal women are at especially high risk.
The Pennsylvania researchers could not determine from their study whether the teen-agers' increased bone mass meant that the girls were simply reaching their peak bone mass faster than those who didn't take calcium supplements, or that the increase could be maintained, and even built upon, throughout adulthood.
Mr. Lloyd said he is betting on the latter.
"I would speculate that some gain will remain, because we see an increase in bone area -- the girls have bigger bones," he said. "And bigger bones make stronger bones."
Previous research has suggested that a 5 percent increase in bone mass can reduce a person's future fracture risk by 50 percent, according to Mr. Lloyd.
The scientists will continue to study the teens through age 21.
Dr. Lawrence Raisz, head of endocrinology at the University of Connecticut in Farmington, said he was skeptical that a 4 percent rise in bone mass would translate to a 50 percent reduction in fracture risk.
Regardless, such an increase in bone mass still would benefit these young women -- assuming the gain is maintained, he said.
While Mr. Lloyd and Dr. Raisz agreed that increasing people's calcium intake is important, they differed over the best way to achieve optimal levels of the nutrient.
"The question is: Is supplementation the way to go?" Mr. Lloyd asked. "There's already low-fat yogurt, which has about 400 milligrams of calcium per half-pint. We could also fortify our food. Wonder bread already has a high-calcium bread out."
Dr. Raisz favored an even simpler approach. "Supplements are good, but a glass of milk is a lot cheaper," he said.