Years ago, when children drank lots of milk and spent much of their time playing outside in the sunlight, parents and physicians didn't worry if kids were getting enough vitamin D. Today, with children often consuming fewer dairy products and spending more time indoors playing video games, pediatricians like me are seeing many more young patients who are deficient in vitamin D, which is critical for healthy bone development.

I'm thrilled that so many parents these days are diligent in using sunscreen to protect their children from skin cancer. But what many people may not realize is that by blocking the sun's rays, we make it more difficult for the body to manufacture vitamin D on its own. In addition, some children have limited intake of fortified dairy products and some parents are embracing vegan lifestyles. These are just some of the factors that may account for the significant rate of vitamin D deficiency we're increasingly seeing in otherwise healthy American children.

The human body needs vitamin D to absorb and retain calcium and phosphorus that are essential for healthy bone formation. A deficiency in this key nutrient can cause rickets, which can stunt a child's growth and lead to weakened bones that are more easily broken. It can also contribute to osteoporosis, or low bone density, in later years.

In 2014, in response to this growing problem, the American Academy of Pediatrics updated the amount of Vitamin D it recommends. Infants under 12 months of age, regardless of whether they are breast-fed or bottle-fed, should be given daily supplement drops that provide 400 IU of the vitamin. Older children and adolescents should receive a daily dose of 600 IU, whether through diet, sun exposure or supplementation.

While medical opinions vary on what constitutes a healthy blood level of vitamin D, doctors like me look for a minimum of 20 nanograms per milliliter, determined through a simple blood test. Your pediatrician will let you know if such a test is needed, based on your child's dietary habits and activity level, and on increased risk factors for deficiency. Kids taking certain medications, and those with chronic diseases such as cystic fibrosis, may need higher doses of Vitamin D.

If your child is found to be Vitamin D deficient, don't panic. The good news is that it's very easy to boost Vitamin D intake - through sun exposure, diet and supplementation. The best dietary sources of vitamin D include fortified dairy products (such as milk); fortified orange juice; fortified breakfast cereals; egg yolks; and fatty fish, such as salmon, sardines and mackerel. If your pediatrician recommends a multivitamin for your child, check to see that it contains the recommended 600 IU of vitamin D per day. (It is possible to overdose on vitamin D, so be extremely careful with supplement dosing.)

While we do want to limit our children's exposure to harmful UV rays, 10 or 15 minutes of sun exposure at midday, without sunscreen, is an excellent way to boost vitamin D levels for most children. Darker-skinned individuals need more time in the sun to achieve this benefit, however, so supplementation might be needed if adequate sun exposure is not possible. It's up to parents - in concert with their pediatrician - to balance the risks and benefits for their children of a little play time outdoors without sunscreen.

Also, keep in mind that in the winter months, the sun's radiation effect is not sufficient to maintain healthy levels of vitamin D, so supplementation is often needed. Finally, healthy bones require both calcium and vitamin D. So be sure to review your child's calcium intake with your pediatrician or a nutritionist. A minimum daily intake of 500 mg is recommended for all children over the age of 12 months.

To learn more about the importance of vitamin D, visit:


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C. Michele Christie, M.D., is a board-certified pediatric endocrinologist with the Mid-Atlantic Permanente Medical Group in the Washington, D.C. area. She completed her training in pediatric endocrinology at the University of Virginia and sees patients in the Kaiser Permanente Kensington Medical Center.