Vitamin D and COPD
Chronic obstructive pulmonary disease patients have high rates of vitamin D deficiency — over half in most cohorts. Reduced sun exposure, low BMI (or the opposite: obesity), chronic corticosteroid use, and reduced mobility all contribute. Deficiency correlates with more frequent exacerbations.
The ViDiCO trial
The 240-patient ViDiCO trial (Martineau 2015) gave 120,000 IU cholecalciferol every 2 months vs placebo to COPD patients. Overall: no significant reduction in moderate-to- severe exacerbations. But pre-specified subgroup analysis showed a 45% reduction in exacerbations in patients with baseline 25(OH)D < 20 ng/mL — the same pattern seen in asthma trials.
Cochrane meta-analysis
A 2019 Cochrane review pooling 4 trials found a 43% reduction in exacerbation rate in adults with baseline 25(OH)D < 25 nmol/L (< 10 ng/mL). No benefit in vitamin D-replete patients. The evidence supports correcting deficiency, not supplementing indiscriminately.
Mechanism
Cathelicidin (LL-37) is a vitamin D-inducible antimicrobial peptide that helps clear the respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae, viruses) that trigger COPD exacerbations. Vitamin D also downregulates airway inflammation and remodelling pathways.
Practical dosing
- Test 25(OH)D in all COPD patients, especially those with ≥ 2 exacerbations per year.
- If < 20 ng/mL: 2,000–4,000 IU/day for 8–12 weeks, then re-test.
- Target maintenance 30–50 ng/mL.
- Chronic inhaled or oral corticosteroids also warrant DEXA and osteoporosis workup — vitamin D + calcium is standard.