Vitamin D for Cold Prevention
A landmark individual-participant meta-analysis (Martineau et al.) found daily/weekly vitamin D reduced acute respiratory infection risk, with the largest effect in those with 25(OH)D under 25 nmol/L. Correcting deficiency is a reasonable cold-season strategy.
Overview
Verdict
Vitamin D supplementation reduces acute respiratory infections, with strongest benefit in deficient individuals.
How It Works
Dosing & Protocol
Typical dose
- Recommended dose
- 1,000–4,000 IU D3/day to sufficiency (30–50 ng/mL).
- Expected timeframe
- 8–12 weeks to replete; benefit assessed across a season.
Protocol
- form
- Vitamin D3 (cholecalciferol) taken daily - the meta-analysis found daily or weekly dosing effective and bolus dosing ineffective
- duration
- Through the autumn and winter months
- co factor
- Take daily with a fat-containing meal; do not use large intermittent bolus doses for this purpose. Evidence is mixed. The Martineau individual participant data meta-analysis of 25 randomised trials found vitamin D supplementation reduced acute respiratory tract infection risk overall, with the protective effect concentrated in people with baseline 25(OH)D below 25 nmol/L, who saw a substantial reduction, and in those given daily or weekly rather than bolus doses. Subsequent large trials including VITAL and D-Health found no reduction in respiratory infection in largely replete populations, and an updated meta-analysis attenuated the effect.
- titration
- Up to 2,000 IU/day; 4,000 IU/day is the tolerable upper intake level
- starting dose
- 400-1,000 IU/day of vitamin D3 with a meal containing fat
Evidence
Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials
Jolliffe DA, Camargo CA, Sluyter JD +1 more
Protection was associated with administration of daily doses of 400-1000 IU for up to 12 months, and age at enrolment of 1.00-15.99 years.
Safety
Caveats
Bolus dosing does not work — daily or weekly only. Test levels before supplementing high doses.
Less likely to help if
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.