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'Got Bones': NMSU Researchers Study Hispanic Adolescent Bone Health

LAS CRUCES - New Mexico State University scientists are taking a closer look at barriers that keep Hispanic girls from getting enough calcium during their peak bone-building years. Although calcium intake in childhood and adolescence is critical to long-term bone health, not enough tweens and teens find future bone-protection persuasive enough to add enough dairy food to their diet.



Ann Bock, left, a registered dietitian with New Mexico State University's Agricultural Experiment Station, demonstrates how bone length measurements are taken with the study's site coordinator, Deanna Lavanty. The bone dimensions are being used in a nationwide U.S. Department of Agriculture study examining the motivators and barriers to consuming calcium among Hispanic youth, especially teen girls. (06/03/2003) (NMSU Agricultural Communications Photo by J. Victor Espinoza)

As part of a major grant from the U.S. Department of Agriculture, NMSU researchers are participating in a four-year study of Hispanic sixth graders in southern New Mexico to measure their understanding of the importance of calcium-rich foods in their diets, and to see just what they're eating and avoiding at this age.

"We chose 11- and 12-year-olds because that's when we see a precipitous drop in calcium intake, and that drop is worse in girls than it is in boys," said Ann Bock, a registered dietitian with NMSU's Agricultural Experiment Station. Fear of getting fat may be one reason why so many adolescents stop drinking milk, especially teen girls.

Using computer-based surveys and interactive DVD and CD-ROM teaching tools, Bock is using middle school science classes in the Las Cruces area to fortify the children's ability to recognize calcium-loaded foods, and see if there's a connection between what they consume now and development of strong bone development and prevention of the bone-thinning disease osteoporosis later in life.

Osteoporosis develops as the body removes old bone in a natural process called resorption, but fails to produce enough bone to replace it. Typically, a person's bone mass peaks around age 30 and diminishes slowly until age 80. According to the World Health Organization, 70 percent of women suffer from osteoporosis.

The CD-ROMs, developed by NMSU's agricultural communications department, include educational games, videos and other interactive features. To test the teaching tools' effectiveness, measurements are taken before and after the programs to measure changes in participant's bone measurements and density.

The $3.75 million USDA project, which will be completed next year, is a nationwide effort aimed at gauging the motivators and barriers to consuming calcium among Anglo, Hispanic and Asian young people. In involves researchers from six universities: NMSU, Purdue, Hawaii, Nevada-Reno, University of California - Davis and Ohio State. Bock explained that previous studies found that Asians and Anglos are high-risk groups for osteoporosis and fractures later in life, while Native Americans and Hispanics have moderate risk and African-Americans have low risk.

"The problem is that we have very little data on Hispanics period, and almost none on
Hispanic children," she said. "In our case, we believe we'll see that a lot of these children in this part of the country get their calcium from nonliquid dairy sources and nondairy sources." Cheese is the most prominent source of calcium for these Hispanic young people, Bock said. Nondairy sources of calcium include pinto beans and corn tortillas.

Adolescence is a critical time for bone health, Bock said. The vast majority of the body's bone is formed by the end of the teen years, and dropping calcium in middle and high school years sets the stage for future physical problems, she said.

The effects of a calcium-deficient diet on children may not become apparent until they reach age 60, but they can be catastrophic, Bock said. Osteoporosis ranks near the top of the nation's debilating diseases, and is a contributing factor in huge numbers of fractured bones among the elderly.

"Many, many people who sustain a fracture never regain their mobility," she said.
Decades of research indicate three factors increase the likelihood of developing osteoporosis later in life: low calcium intake over the course of a lifetime, lack of weight-bearing physical activity and a decline in estrogen levels with age.

"So many people have the idea that once you're past being a baby, you don't have to have good sources of calcium like milk," Bock said. "In fact, they think you don't have to have milk at all. Consequently, we see a calcium drop-off, particularly with dairy."

In terms of physical exercise, she said that Americans are too often known for their life-long sedentary lifestyles. "Working out from the time you're 15 to 22 isn't enough," Bock said. "It's something that you should be doing throughout life."

And while estrogen affects both men and women as a naturally occurring hormone in the body, the significant loss of estrogen by menopausal women has profound consequences in the amount of calcium deposited and retained in the bones. "The risk of osteoporosis goes up fairly dramatically for women," she said.

Bock said that studying those factors influencing calcium intake among Hispanic adolescents has already deepened researchers' understanding of ethnic differences and reinforced that there's not a "one approach fits all" solution to teaching the benefits of calcium. "We're also finding that there are strong parental influences - the mom factor - in food preferences, especially among younger Hispanic adolescents," she said