By Sumathi Reddy

Bone health and osteoporosis are typically thought of as issues that affect people later in life.

But the groundwork for such conditions is laid in childhood and adolescence, experts say, making bone health crucial during those stages. About half of the skeleton’s density is developed during puberty.

“You can’t wake up when you’re 50 and say, ‘I think I’m going to fix my bones now,’ ” saysLaura Bachrach, a pediatric endocrinologist and professor of pediatrics at Stanford University School of Medicine and co-author of a clinical report on bone densitypublished this month in the journal Pediatrics. “The time you want to be working on this is through childhood, especially in adolescence, so that you have the healthiest bones you possibly can.”

Experts say ensuring adequate levels of calcium and vitamin D and regular physical exercise—particularly when it’s weight-bearing—are important in developing and maintaining healthy and strong bones.

Peak bone mass typically occurs between ages 20 and 30. After that, as people age, they naturally lose bone mass. This can be exacerbated by some medications. For women, the decade in which menopause occurs results in an especially steep decrease in bone density, which leads to a higher risk of developing osteoporosis.

Getting enough calcium is important for bone growth and health. Children under 9 should get 800  milligrams a day, while other children should get 1,300 milligrams a day. PHOTO: ISTOCK

Studies have found an increase in childhood fractures of between 35% to 65% over the past four decades. Experts aren’t sure why, but note that deficiencies in vitamin D, calcium and a lack of physical activity increase the risk of developing fractures.

“We’re very suspicious of fractures in the spine, hip or femur unless there’s a major motor vehicle accident,” Dr. Bachrach says.

Also important is distinguishing between traumatic fractures—such as a child falling from the top of a jungle gym—versus a low-trauma fracture, generally defined as happening at standing height or less, Dr. Bachrach says. “The fracture number matters, but you have to find out how they occurred,” she says.

Family history also plays an important role—80% of bone density is dictated by genetic factors, says Catherine Gordon, director of adolescent and transition medicine at Cincinnati Children’s Hospital and a co-author on the Pediatrics report. Athletes should have a higher than average bone density because of their frequent weight-bearing activity, she says.

Though the report doesn’t recommend universal bone density testing for all children, it cautions parents to be aware of three red flags. One is if a child has had two or more fractures before the age of 10 or three or more before age 19. Parents should also consider a test if a child has a vertebral fracture that cannot be explained by a disease or traumatic accident.

Certain health conditions—or the treatment of them—also put children at risk for poor bone health, Dr. Gordon says.

“Every day we’re uncovering different diseases or treatments for underlying diseases that might lead to bone loss in children and adolescents,” Dr. Gordon says. Conditions include pediatric chronic inflammatory diseases such as inflammatory bowel disease, eating disorders, cancer and Type 1 diabetes.

Bone mineral density is measured using a dual-energy X-ray absorptiometry (DXA) scanner. It’s a noninvasive and quick test with a low exposure of radiation. DXA scans are routine for women after menopause to provide a baseline measure of bone density.

Experts recommend regular physical activity to improve bone health. Studies have found that jumping for just 10 minutes three times a week can result in gains in bone mass. PHOTO: ISTOCK

Kathryn Ackerman, medical director of thefemale athlete program at Boston Children’s Hospital, frequently does bone density scans on female athletes with irregular menstrual cycles, repeated bone stress injuries or other risk factors for poor bone health. Some have eating disorders and others are inadvertently consuming fewer calories than they need.

She advises athletes in sports like swimming, which cause little impact on the bones and joints, to mix it up with strength training and playing sports like basketball or soccer. “Multidirectional sports with high impact may lead to stiffer and stronger bones and more fracture-resistant bones,” she says.

Vitamin D plays a big role in developing healthy bones. Experts recommend a vitamin D supplement for children who may not get enough sun. PHOTO: ISTOCK

Bone geometry plays a role in how likely a child is to get a fracture, Dr. Bachrach says. Small children with thin bones may be more vulnerable to fractures. So are obese children. “You get to a point where it’s too heavy a load for the bone,” she says.

In terms of bone health, experts recommend ensuring adequate levels of vitamin D and calcium and regular physical activity.

Even short bursts of exercise have been shown to improve bone mass. A 2014 review article in the Journal of Bone and Mineral Research cites a study that found jumping just 10 minutes a day three times a week resulted in gains in bone mass.

Dr. Bachrach says most kinds of jumping—whether it’s jumping jacks, jumping rope or jumping in place—are beneficial as long as both feet are off the ground at the same time.

Children who use sunscreen daily may need a vitamin D supplement if they don’t get enough of the nutrient when they eat, Dr. Bachrach says. It’s recommended that children and adults get 600 units of vitamin D a day.

Calcium is also important. It’s recommended that children under 9 get 800 milligrams of calcium a day, while older children should get 1,300 milligrams daily. The average American diet without dairy includes about 300 milligrams of calcium a day. Children should have three servings of dairy or other calcium-rich food or drink on top of that to get adequate levels, the researchers say.

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