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Making sure your kids have healthy bones

March 27, 2013

“Dr. Davis, are her bones okay?”

“Did she break her arm because her bones are weak?”

These are two common questions that come up every day in my sports medicine clinic. I see a variety of fractures in young children and teenagers from falling on the playground to various sports injuries. Over the last decade, concern for our children’s bone health has increased dramatically. Are we seeing more fractures in children today than a generation ago? Quite simply, the answer is yes. 

The next logical question is: why are we seeing more fractures? What we know is that there is not one clear reason. There are many factors that play a part in this increase including inadequate bone mass, avoidance of cow’s milk, low dietary calcium and vitamin D intake, lack of physical activity and being overweight.  

Are your kids getting enough calcium?

The vast majority of children and teens do not consume enough dietary calcium and vitamin D on a daily basis. These are two essential nutrients long known for their role in keeping bones strong. On average, 500 mg of calcium per day meets the requirements of 1 to 3-year-olds and 800 mg per day for 4 to 8-year-olds. About 40% of total adult bone mass is accumulated within a 3 or 4 year period during adolescence. Teenagers, therefore, need higher levels of calcium to support bone growth: 1,300 mg per day meets the needs of almost all adolescents. 

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Recent research has shown that short term (1 to 2 years) supplementation of dietary calcium may not have long-term benefits in attaining and maintaining peak bone mass.  This emphasizes the importance of establishing healthy dietary practices in childhood that promote adequate calcium intake throughout life. 

What about Vitamin D?

Determining intake levels for vitamin D is somewhat more complicated. Vitamin D levels in the body may come from not only dietary sources but also from sunlight exposure. The amount of sun exposure varies greatly from person to person. With the increased use of sunscreen and less sun exposure recommended by pediatricians and dermatologists to prevent skin cancer, many children are not getting adequate amounts of vitamin D from the sun. Therefore, children and adults need on average 400 International Units (IUs) of vitamin D per day. Many people are actually low or deficient in vitamin D and could actually benefit from up to 800IUs/day. 

It is important to remember, though, that both vitamin D and calcium can be toxic if taken in large quantities. No one should consume more than 2,000 mg per day of calcium or 4,000IUs per day of vitamin D. Optimizing both calcium and vitamin D intake in childhood and adolescence results in stronger, denser bones in adulthood and reduces the chance of developing osteopenia and osteoporosis later in life.  

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What’s the best way to get calcium and vitamin D?

The source of calcium in optimizing bone health seems to be important. Various studies indicate that consuming milk and other dairy foods during childhood and adolescence is a primary determinant of bone health. Kids who avoid milk are known to have suboptimal bone mass and are at higher risk of fractures. Consuming a well-balanced diet composed of a variety of foods, including dairy products and other calcium-rich foods, fruits and vegetables, grains and meat or beans is the best way to ensure an adequate intake of important bone-building nutrients. 

Other nutrients besides calcium are also critical to bone health. Vitamin D, protein, phosphorus, magnesium, potassium, vitamin B12 and zinc are all needed to make healthy bones. Dairy foods contain a “package” of bone-building nutrients such as vitamin D, magnesium, phosphorus and protein.

The American Academy of Pediatrics (AAP) recommends three 8-ounce glasses of milk a day for children 4 to 8 years of age, and four glasses for teenagers. Alternatives would be three 8 oz. servings of low-fat yogurt or three 1 oz. servings of low-fat cheese. Cottage cheese and calcium-fortified juices or breads are also acceptable. It is best to consume adequate calcium from nutrient-rich food sources rather than supplements whenever possible.

Make sure your kids are moving!

Also concerning in the escalating incidence of fractures is the lower level of physical activity among our kids today and the increasing epidemic of childhood obesity. Higher levels of physical activity have been associated with higher bone mineral density and, therefore, a lower risk of fractures. 

Overweight children have lower bone mass relative to their body weight and are less likely to be physically active than children with a healthy body weight. They also fall with greater force and have more difficulty with general body balance than normal weight kids. Keeping kids active (60 minutes/day of moderate to vigorous activity most days of the week) and limiting “screen time” (TV, computers, video games, iPads, iPods, etc) to less than 2 hours/day along with a healthy diet is essential in keeping kids from becoming overweight. While any physical activity is good, weight-bearing activities are best for building strong bones (walking, running, hiking, dancing, tennis, basketball, gymnastics, and soccer).

Optimizing bone health in childhood and adolescence is essential for development of adequate bone mineral density later in life. Establishing good dietary and physical activity routines as children ensures continuation of these habits into adulthood. Keeping kids healthy is the best way to reduce their overall risk of fractures.

But remember, kids will be kids and a broken bone or two comes along with the territory!