Teen years key for healthy bone growth

For strong, healthy bones throughout their lives, teens need to have the right diet and exercise. A new study found that the late teen years are a key period for bone growth — even after teens have achieved their full adult height.

“We often think of a child’s growth largely with respect to height, but overall bone development is also important,” said lead author Dr. Shana McCormack, a pediatric researcher at Children’s Hospital of Philadelphia. “This study shows that roughly 10 percent of bone mass continues to accumulate after a teenager reaches his or her adult height.”

That study, published in JAMA Pediatrics, included bone and growth measurements during annual visits for up to seven years in over 2,000 healthy, racially diverse children, adolescents and young people from 2002 to 2010.

The study found that bone growth is site-specific, with bone mineral density developing at different rates in different parts of the skeleton.

“We also showed that growth events peak earlier in African-American adolescents than in non-African-American adolescents,” said study co-author Dr. Babette Zemel, principal investigator of the Bone Mineral Density Childhood Study at Children’s Hospital of Philadelphia.

Before adolescence, height growth far outpaces gains in bone mineral, which may explain the high fracture rates among children and adolescents. About 30 to 50 percent of children will experience at least one fracture before adulthood. The “lag” in bone mineral buildup is compensated for after height growth is complete.

To help parents encourage healthy behaviors at a time when teens may be adopting riskier ones, such as smoking and alcohol use, worse dietary choices and decreased physical activity, clinical dietician Jessica Buschmann and Dr. Anastasia Fischer, both with the Department of Sports Medicine at Nationwide Children’s Hospital in Columbus, Ohio, offer the following advice:

Eat well
While vitamin D and calcium are certainly important components of healthy bone formation, an overall healthy diet with adequate fuel for activity and growth is as important, if not more so, for development of a healthy skeleton. We recommend 600 IU (international units) of vitamin D and 1,300 to 1,500 mg of calcium per day (2 percent milk has about 300 mg per cup). This is best absorbed with dairy products; however, fortified food items and supplements should be considered if there is concern for inadequate intake.

Get sporty
Weight-bearing physical activity helps with building a healthy, strong skeleton. Non-weight-bearing sports (such as swimming, cycling, rowing) are important for bone formation as well and should likewise be encouraged, but in combination with weight-bearing conditioning or participation in other sports and activities.

Avoid fatigue
Physical activity should be encouraged in all teenagers for overall health and wellness. However, too much of any activity can fatigue a bone and cause a stress injury. Any teenager experiencing bone pain without injury should be evaluated.

For the girls
Menstrual cycle disturbances can be associated with poor bone health. Girls should track their periods so that if they are going longer than 35 days between cycles, they can bring it to the attention of a medical professional.

Written by Melissa Erickson. Photo by 123RF.

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