Building strong bones in the teen years for strong bones later

Were you wondering why the skeleton didn't dance at the Halloween party? The answer is quite sad really — he had no "body" to dance with.  We wouldn't be dancing either if we didn't have 206 strong bones holding us up, working with our muscles to move, and protecting our vital internal organs. Most of our bone health (60-80 percent) reflects our genetics (so pick your parents carefully!). The rest is in our hands.

It's kind of like building a house. As children and adolescents, we are establishing the foundation for the house that we will live in for the rest of our lives. Instead of concrete, we are using calcium and other minerals. During the 3- to 4-year growth spurt during puberty, nearly half of all bone is formed. Bone formation peaks at 12 and a half years for girls and 14 years for boys. Throughout life, there is constant remodeling going on. When we're young, our body makes new bone (deposition) faster than it breaks down old bone (resorption), and bone mass increases.  Most people reach peak bone mass around age 30. Between 30 and 50 years of age, deposition and resorption are about equal, but as we age (especially women) resorption exceeds deposition and we lose bone mass.

Getting enough calcium is one of the most important things we can do to build healthy bones. Ninety-nine percent of the calcium we consume is stored in bones and 1 percent is used for other biological functions. When calcium intake is low, bone breakdown occurs as the body needs to use the stored calcium to maintain normal biological functions. Based on available research, the recommended daily allowance (RDA) for calcium is 1300 mg for boys and girls 9-18 years of age.  If calcium intake is lower than that, peak bone mass may not be achieved, potentially increasing the risk of fractures and osteoporosis later in life.

Many teens are not getting enough calcium. National data shows that the proportion of children who achieve the RDA for calcium is lowest between the ages of 12-19 years — exactly when bone formation peaks and the need for calcium is at its highest. Most children are getting 500-1000 mg/day, and only 1 out of 10 adolescent girls get 1300-mg.

How best to get calcium? From food! Calcium from the diet is optimal as food provides multiple nutrients that are important for bone health, including calcium, phosphorus and magnesium. Milk, including low fat milk, yogurt and cheese are our major natural sources of calcium. About 4 and a half glasses of milk or other calcium-rich foods a day provide the 1300-mg RDA of calcium. Check out all of these great sources of calcium. Some foods, including breakfast cereals and juices, may be fortified with calcium. Vegetables like kale and broccoli are also good sources of calcium.

What about calcium supplements? For children and teens who cannot get enough dietary calcium, calcium supplements may be "prescribed." The two most common forms of calcium in supplements are calcium carbonate and calcium citrate malate. Calcium carbonate needs to be taken with food and may have side effects such as gas and bloating.  Calcium citrate malate can be taken with or without food, and it is better absorbed by the body.

Don't forget Vitamin D! Vitamin D supports bone development by increasing the body's absorption of calcium from food. It is recommended that children and teens get 600 International Units (IU) of vitamin D daily. Most of us get all the vitamin D we need from everyday exposure to the sun, which triggers an internal chemical reaction that produces vitamin D. The sunshine vitamin is also in foods, including canned salmon with bones and egg yolks. Recent studies have shown that 40 percent of teens are deficient in vitamin D.

And don't forget exercise! It is well known that astronauts and other non-weight-bearing or immobile people rapidly lose bone mass. In general, studies find that moderate weight-bearing activity, such as running or jumping, has a more positive effect on bone mass than do non–weight-bearing activities such as swimming. Teens' bones respond to weight-bearing exercise by growing stronger and denser. There is evidence that childhood and adolescence is an important period for achieving long-lasting skeletal benefits from exercise. It is recommended that children and teenagers do bone-strengthening exercise for 20-30 minutes three times a week.

My advice: As parents, we need to pay attention to what's in our shopping cart to help our kids reach their peak bone mass. In most cases, if your teens get their 1300 mg of calcium a day along with 10 minutes of sunshine, they will be able to dance at the Halloween party.

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