Vitamin D

Is it better to take vitamin D daily or in large doses less often?

Updated 3 Nov 2026

Short answer

Daily or weekly doses have the better record. In a 2017 analysis of 25 trials, daily or weekly vitamin D lowered the odds of respiratory infections by 19%. Large single (bolus) doses did not lower them.[1]

In older women, one dose of 500,000 IU a year raised falls by 15% and fractures by 26%.[2] A 2025 review of respiratory infections found no difference between daily and less frequent doses.[3]

Sources (3)

  1. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, et al. BMJ, 2017. PMID 28202713
  2. Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial. Sanders KM, Stuart AL, Williamson EJ, Simpson JA, Kotowicz MA, Young D, et al. JAMA, 2010. PMID 20460620
  3. Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data. Jolliffe DA, Camargo CA Jr, Sluyter JD, Aglipay M, Aloia JF, Bergman P, et al. Lancet Diabetes Endocrinol, 2025. PMID 39993397

More about vitamin d

What is vitamin D?How do you get vitamin D from sunlight and food?What is vitamin D used for?What vitamin D blood level is too low?Is vitamin D safe?Does vitamin D prevent fractures?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.