What are the recommendations for vitamin D (Vitamin D) supplementation in children?

Vitamin D Supplementation in Children

Universal Supplementation Recommendations

All infants, children, and adolescents should receive daily vitamin D supplementation with age-specific dosing: 400 IU/day for infants 0-12 months and 600 IU/day for children and adolescents 1-18 years. 1

Standard Maintenance Dosing by Age Group

• Infants 0-12 months: 400 IU/day from all sources (diet plus supplements), regardless of feeding method 1, 2
• Children and adolescents 1-18 years: 600 IU/day from all sources 1
• Preterm infants on parenteral nutrition: 200-1,000 IU/day (or 80-400 IU/kg/day) 1

The rationale for universal supplementation stems from the high prevalence of vitamin D insufficiency globally—approximately 30% of children are deficient—and the proven efficacy of 400 IU daily in preventing rickets 3, 4. Breastfed infants and children consuming less than 1 liter of fortified milk daily will require supplementation to meet these targets 2.

Duration of Supplementation

• Universal supplementation is strongly recommended from shortly after birth until 12 months of age 4
• Beyond 12 months: Continue supplementation through adolescence, particularly for at-risk groups including those with limited sun exposure, darker skin, obesity, low milk consumption, or low socioeconomic status 5

Treatment of Vitamin D Deficiency

When deficiency is identified (25[OH]D <20 ng/mL), higher therapeutic doses are required before transitioning to maintenance therapy.

Treatment Regimens Based on Severity

For mild deficiency (5-15 ng/mL):

• 4,000 IU/day orally for 12 weeks, OR
• 50,000 IU every other week for 12 weeks 1

For vitamin D insufficiency (16-30 ng/mL):

• 2,000 IU daily for 12 weeks, OR
• 50,000 IU every 4 weeks 1

For severe deficiency (<5 ng/mL):

• Use the mild deficiency regimen but assess for clinical rickets (bowing of legs, rachitic rosary, delayed fontanelle closure) 1
• Check serum calcium, phosphorus, alkaline phosphatase, and parathyroid hormone to evaluate for metabolic bone disease 1

Post-Treatment Protocol

• Recheck 25(OH)D levels after 12 weeks to confirm normalization above 20 ng/mL 1
• Transition to age-appropriate maintenance dosing (400-600 IU/day) once levels normalize 1
• Monitor levels every 6-12 months, especially during winter months when sun exposure is limited 1

Formulation Selection

Cholecalciferol (vitamin D3) is preferred over ergocalciferol (vitamin D2) due to higher bioefficacy, though long-term comparative trials in children are limited 6, 1. This is particularly important in treatment regimens where achieving target levels efficiently is critical.

Safety Thresholds and Upper Limits

The Institute of Medicine established age-specific upper tolerable limits to prevent toxicity 1:

• 0-6 months: 1,000 IU/day maximum
• 7-12 months: 1,500 IU/day maximum
• 1-3 years: 2,500 IU/day maximum
• 4-8 years: 3,000 IU/day maximum
• 9-18 years: 4,000 IU/day maximum

Prolonged daily intake up to 10,000 IU appears safe, but serum concentrations >375 nmol/L are associated with acute hypercalcemia and hyperphosphatemia 1. Vitamin D toxicity is rare at recommended doses but requires monitoring in treatment regimens 1.

Special Populations Requiring Modified Approach

Children with Chronic Kidney Disease

Children with CKD stages 3-5 have an 80-90% prevalence of vitamin D insufficiency and may require higher or more frequent supplementation 6, 1. However, optimal dosing is not well-established, and calcium and phosphorus must be monitored closely to avoid hypercalcemia 1. Even in advanced CKD, correcting nutritional vitamin D deficiency with ergocalciferol or cholecalciferol is appropriate before considering active vitamin D analogs 6.

Children on Parenteral Nutrition

• Monitor 25(OH)D levels periodically 1
• Provide additional supplementation if levels fall below 50 nmol/L (20 ng/mL) 1
• Consider oral supplementation during weaning from parenteral nutrition 1
• Administer vitamins with lipid emulsion when possible to increase stability 1

Common Pitfalls and How to Avoid Them

Do not use active vitamin D analogs (calcitriol) to treat nutritional vitamin D deficiency—these are reserved for specific conditions like CKD with impaired 1-alpha-hydroxylase activity 1. Nutritional deficiency responds to cholecalciferol or ergocalciferol.

Ensure treatment adherence, as inconsistent supplementation is a common cause of treatment failure 1. Consider monthly high-dose regimens (50,000 IU) if daily adherence is challenging, as one capsule monthly approximates 2,000 IU daily 6.

Ensure adequate dietary calcium intake during treatment, as vitamin D improves calcium absorption and inadequate calcium can limit the effectiveness of vitamin D therapy 1.

Recognize that decreased sun exposure increases deficiency risk, but the American Academy of Pediatrics recommends keeping infants out of direct sunlight, making supplementation even more critical 2, 5.

Target Serum Levels

The treatment goal is to achieve and maintain 25(OH)D levels above 20 ng/mL (50 nmol/L) for bone health 1. Some evidence suggests levels of 30 ng/mL (75 nmol/L) may optimize extraskeletal benefits, though randomized controlled trials demonstrating patient-oriented outcomes at this threshold in children are lacking 7, 3.