Dr. Kumar’s Take:
This small but detailed trial found that giving two large doses of vitamin D (100,000 IU) to preschoolers with asthma in the fall and winter raised their blood vitamin D levels quickly—but the effect didn’t last. After about 3.5 months, most kids’ levels dropped back down, meaning the boluses weren’t enough to keep levels optimal through the entire season. For sustained vitamin D sufficiency, a daily supplement is likely needed along with these boluses. On the upside, the study showed this high dose was safe, even in young children.
Key Takeaways:
✔ Two doses of 100,000 IU vitamin D3 spaced 3.5 months apart safely raised blood levels in preschoolers.
✔ Vitamin D levels spiked quickly but fell back near baseline after 3.5 months.
✔ Only about half of kids stayed vitamin D sufficient (≥75 nmol/L or 30 ng/mL) over 7 months.
✔ No serious side effects were reported, even at peak vitamin D levels.
Actionable Tip:
For children with asthma—especially in northern climates—consider pairing high-dose vitamin D boluses with a low daily supplement (e.g. 400 IU/day) during fall and winter to maintain sufficiency and potentially reduce respiratory flare-ups.
Study Summary: Vitamin D Boluses in Asthmatic Preschoolers
This randomized, placebo-controlled pilot trial studied 47 preschoolers (aged 1–5) with asthma triggered by viral infections. Children received either two large oral doses of vitamin D (100,000 IU) or placebo—once in the fall and once in the winter. The main goal was to see if this approach could raise and maintain vitamin D levels above 75 nmol/L (30 ng/mL), a threshold linked to better immune and asthma outcomes.
Study Design:
- Type: Triple-blind, placebo-controlled pilot RCT
- Duration: 7 months
- Participants: 47 preschool children with viral-triggered asthma
- Intervention: Two oral doses of 100,000 IU vitamin D3 (3.5 months apart)
- Control: Identical placebo doses
- Main Outcome: Blood levels of 25-hydroxyvitamin D (25OHD)
Results:
- Vitamin D levels jumped by ~100–120 nmol/L (40–48 ng/mL) just 10 days after each bolus.
- By 3.5 and 7 months, the difference between groups was no longer significant.
- At 3.5 and 7 months, only 63% and 56% of the vitamin D group remained sufficient.
- Hypercalciuria occurred in 8.7% of vitamin D samples, but there were no cases of hypercalcemia.
- No reduction in asthma attacks, emergency visits, or corticosteroid use was observed—though the study wasn’t powered to detect this.
Why Vitamin D Matters for Asthmatic Kids
Vitamin D plays a role in immune regulation and has been linked to fewer viral respiratory infections and asthma flare-ups. Many kids with asthma are vitamin D insufficient—especially in northern latitudes during fall and winter. This study highlights the challenge of maintaining optimal levels with bolus-only strategies.
Related Studies and Research
Global Prevalence of Vitamin D Deficiency: A Meta-Analysis – Maps worldwide deficiency rates to contextualize population risk.
Effect of Two 100 000 IU Vitamin D₃ Bolus Doses on Viral-Induced Asthma in Preschoolers – Pilot RCT evaluating high-dose vitamin D for asthma exacerbation prevention.
Study Revealing Obesity-Induced Suppression of CYP2R1 and Vitamin D Deficiency – Mechanistic insights into how obesity downregulates the 25-hydroxylase enzyme.
Role of Vitamin D and Calcium in Type 2 Diabetes Prevention: A Systematic Review and Meta-Analysis – Examines nutrient synergy on glycemic control and diabetes risk.
Vitamin D Status Modulates Mitochondrial Oxidative Capacity in Skeletal Muscle: Implications for Sarcopenia – Links 25(OH)D levels to muscle energy metabolism and age-related loss.
Frequently Asked Questions
Is 100,000 IU of vitamin D safe for kids?
Yes, in this study it was well-tolerated. No child had high blood calcium or symptoms related to overdose, though a few had mildly high urine calcium without consequences.
Does this help prevent asthma attacks?
This study wasn’t large enough to prove that. However, other trials suggest vitamin D may reduce asthma exacerbations, especially in children with low baseline levels.
Why not just take daily supplements?
Daily supplementation works too—but can be hard to stick to. Boluses help ensure rapid correction of deficiency, especially when adherence is poor.
Can I use this strategy with my child?
Always check with a healthcare provider before giving high-dose vitamin D to children. Individual factors (weight, diet, sun exposure, baseline levels) matter.
Conclusion
In preschoolers with asthma, two high-dose vitamin D boluses raised vitamin D levels quickly and safely. But the effect faded over time, with nearly half of the kids falling below optimal levels by 3.5–7 months. A combination strategy—bolus plus daily low-dose vitamin D—may offer the best of both worlds. More research is needed, but this study helps shape how we think about seasonal vitamin D support in young children with chronic conditions.