Osteoporosis Research : Early Calcium Intake Beneficial, Study Says

The teen-age years could be the prime time for females to take calcium and ward off brittle and broken bones 40 years later, a University of Washington researcher said Tuesday.

Dr. Charles H. Chesnut, professor of medicine and radiology at the university, said in an interview that the adolescent years--when bone density and size are determined--are the best time to take bone-building calcium and possibly prevent osteoporosis, a bone disorder that plagues many post-menopausal women.

1,000 Doctors Attend

The conclusions were made in a pilot study presented by Dr. Velimir Matkovic, one of several authors, along with Chesnut, at the American Society for Bone and Mineral Research convention this week at the Disneyland Hotel.

Osteoporosis, a loss of bone tissue that threatens the health of many elderly women, is one of the chief topics of discussion at the national convention, attended by about 1,000 physicians. Chesnut, the principal investigator for the study, said the research team determined that teen-age girls are able to store extra amounts of calcium by taking moderate to high doses of the mineral.

Ongoing studies will determine whether girls who take extra calcium develop larger and more dense bones, a premise supported by previous research, according to Chesnut, who is treasurer of the National Osteoporosis Foundation.

In the study, researchers focused on teen-age girls because the human skeleton achieves “peak bone mass”--size and density--between the years of 12 and 25, with the average age being 16 or 17 years, Chesnut said.

The study examined 31 girls at age 14 whose calcium intake varied individually from 200 to 1,600 milligrams a day, he said. The federal recommended daily allowance is 1,200 milligrams, he added.

The average amount taken was 1,000 milligrams, or 1 gram, indicating that most girls in the study were ingesting sufficient calcium, either through tablets or dairy products, although 25% were consuming less than 800 milligrams and were “calcium deficient,” Chesnut said.

The researchers then traced the calcium retention of 18 of the girls by measuring how much of the mineral they ingested compared to the amount they expelled through body wastes.

The girls achieved “positive calcium balance”--that is, they retained as much calcium as they lost--about 600 milligrams, Chesnut said. If they took less than that, they actually lost calcium, presumably from their bones, he said. The greatest calcium balance was achieved at 1,500 milligrams, he pointed out.

The data suggests that “the more calcium you take, the better result one might expect getting it into the bone,” Chesnut said.

“We think this can have an effect 30 or 40 years later. . . . Since bone mass is the largest determinant of (susceptibility to) fracture, they (adolescent girls) could be at less risk” for bone fracture when they are post-menopausal.

The researchers plan to study the size of the girls’ spines and wrists in a few months, a year after the study was begun, to determine whether increased calcium had an effect on bone mass. Other follow-up studies are planned, Chesnut said.

The researchers also found that girls who took calcium carbonate tablets retained more calcium than those who ingested the mineral through milk and other dairy products. It is possible that the phosphorous in the milk “bound to the calcium” and prevented its absorption in the digestive system, he said. Calcium carbonate contains no phosphorous.

However, Chesnut said he would not recommend the tablets over dairy products for calcium because the study group was too small and there could have been other variables.

“This requires much more research and evaluation rather than looking at just 31 individuals,” he said.