By Ailing Chen, MD, Pediatrician

Vitamin D insufficiency has become increasingly common among adolescents over the past decade. Vitamin D is an essential nutrient that supports bone growth and helps keep bones strong. Research has found that at least 17% of adolescents and 32% of young adults are deficient in vitamin D, putting them at risk for injury.

Vitamin D helps the body absorb and retain calcium and phosphorus, which are essential for building strong bones—especially during adolescence. In fact, up to 90% of peak bone mass is achieved during these years. Insufficient vitamin D during this critical period can reduce bone strength, increasing the risk of stress fractures or sports-related injuries in adolescence, as well as osteoporosis later in adulthood. Beyond bone health, vitamin D also plays an important role in muscle function, immune health and possibly mood regulation.

The body’s main source of vitamin D is sunlight. When bare skin is exposed to the sun’s ultraviolet B rays, they interact with a form of cholesterol and synthesize into vitamin D. Compared to earlier generations, today’s adolescents spend significantly more time indoors, leading to higher rates of insufficiency. Hours on phones, tablets, computers and gaming systems have largely replaced outdoor activities, resulting in limited sun exposure, even in the summer months.

Winter months further increase the risk of vitamin D insufficiency. In Ohio, cold temperatures, cloudy days, shorter daylight hours and heavier clothing make it difficult to get adequate sun exposure. Even when teens are outdoors, winter sunlight is often insufficient for the skin to produce enough vitamin D.

Vitamin D insufficiency can be subtle and easily overlooked. Some adolescents may experience fatigue, muscle aches, bone discomfort, frequent illnesses, or even symptoms of depression. Vitamin D insufficiency can be diagnosed and monitored through blood testing during annual wellness visits with a primary care doctor.  

So, how can we ensure our children get enough vitamin D? Outdoor activity remains important when weather permits, even for brief periods of sun exposure. Dietary sources of vitamin D include fatty fish such as salmon and tuna, egg yolks and fortified foods like milk, plant-based milk alternatives, cereals and orange juice.  

Current American Academy of Pediatrics recommendations suggest 600 international units (IU) of vitamin D daily for adolescents. Some children may require higher doses if their vitamin D levels are low. Discuss vitamin D supplementation with your child’s healthcare provider to ensure adequate intake and support long-term bone and overall health.