Vitamin D for Teenagers
Adolescence is the peak bone-mass window — roughly 90% of adult bone mass is acquired by age 18. Vitamin D and calcium adequacy in these years shapes lifetime osteoporosis and fracture risk. Teenage deficiency is common and rising — screen time and indoor lifestyles reduce sun exposure, and dietary calcium intake often falls short.
RDA for teens
- Ages 9–18: 600 IU/day cholecalciferol (IOM/AAP).
- Calcium: 1,300 mg/day — highest of any life stage.
- UL: 4,000 IU/day.
- Endocrine Society suggests 1,000 IU/day for teens at risk of deficiency (dark skin, obesity, limited sun).
Deficiency prevalence
NHANES data: ~40% of US adolescents have 25(OH)D < 20 ng/mL; higher in Non-Hispanic Black (~85%) and Hispanic teens (~65%). UK NDNS: 20% of adolescents deficient in winter. Screen time, indoor after-school hours, and dietary shifts all contribute.
Sports and stress fracture
Adolescent athletes — particularly in running, gymnastics, dance, and military-track preparation — have elevated stress-fracture rates. Vitamin D + calcium adequacy is one modifiable protective factor. See our athletes page. Screening 25(OH)D in adolescent athletes is reasonable.
Body image and eating disorders
Restrictive eating patterns in adolescence (anorexia, orthorexia, restrictive weight cutting for sport) often produce low vitamin D and low calcium intake, adding bone-density loss to the many other harms. Screening and multidisciplinary care are essential.
Practical guidance
- Encourage outdoor activity 15–30 minutes daily in warm months.
- Standard multivitamin providing 400–800 IU vitamin D is reasonable for teens with limited sun or dietary vitamin D.
- Ensure dairy or fortified plant-milk intake for calcium.
- Test 25(OH)D in symptomatic teens, athletes with stress-fracture history, or teens with restrictive dietary patterns.
- Winter supplementation (1,000 IU/day cholecalciferol) reasonable for northern-latitude adolescents.