Dosage · Supplement
Vitamin D: dosage and how to take it
1,000–2,000 IU (25–50 µg) D3 daily with a fatty meal.
- Overall grade
- Grade A
- Last revised
- 0
- graded outcomes
- 2
- references listed
Assembled by the app from other entries in this library. It adds no evidence of its own — follow the links to the entries it draws on.
Up: Serum 25(OH)D (ng/mL). Across: IU/day. Roughly linear in the ordinary range; individual response varies with body fat and baseline.
The evidence in words
How much to take
Dose against a blood level, not a calendar. 1,000–2,000 IU/day maintains most adults; frank deficiency often needs 4,000 IU/day for 8–12 weeks then a re-test. Take it with the largest fatty meal of the day for absorption. Pair with vitamin K2 and adequate magnesium, both cofactors for putting the mobilized calcium where it belongs.
Timing & separation
There are no strict timing conflicts on record for Vitamin D; consistency matters more than the exact hour for most goals.
Why the dose is what it is
Calcitriol regulates the transcription of hundreds of genes, most importantly those controlling intestinal calcium and phosphate absorption and bone remodeling. It also modulates immune-cell behavior, which is the mechanistic hook behind the (largely unproven) claims about infections and autoimmunity. Blood 25(OH)D is a storage marker; the body tightly controls how much active calcitriol it makes from it.
Bottom line
If you live away from the equator, get a 25(OH)D test. If you're low, 1,000–2,000 IU/day with a fatty meal, K2 and magnesium alongside, re-test at 12 weeks. If you're already replete, more does nothing — the megadose-prevents-everything story did not survive the big trials.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Maintenance
- 1,000–2,000 IU (25–50 µg) D3 daily with a fatty meal.
- Repletion
- 4,000 IU/day for 8–12 weeks against a low 25(OH)D, then re-test.
- Cofactors
- Take with vitamin K2 (MK-7 90–180 µg) and ensure magnesium sufficiency.
Goes with
- Vitamin DFull Vitamin D monographEvidence grade A
Questions people ask
IU or a blood level?
Dose to the blood level. IU is the input; 25(OH)D is the output that actually matters, and people respond very differently to the same dose.
D2 or D3?
D3 (cholecalciferol) raises and holds 25(OH)D more reliably than D2 (ergocalciferol).
Related reading
Entries that share this one's tags or conditions.
- Vitamin D for Autoimmune diseaseEvidence grade C — VITAL hinted at a small reduction; not establishedEvidence grade C
- Vitamin D for Cancer / CVD prevention (replete adults)Evidence grade D — VITAL and others nullEvidence grade D
- Vitamin D for Correcting deficiency (25(OH)D)Evidence grade A — Dose-dependent, predictable riseEvidence grade A
- Vitamin D for Fracture / fall risk (deficient elderly + calcium)Evidence grade B — Benefit concentrates in the deficient and institutionalizedEvidence grade B
Sources
As this entry records them: title, journal and year. None carries a DOI or PubMed id, so none is linked as a verified paper. Each link searches PubMed for the title; check that what you find is what the entry describes.
- 1.Vitamin D supplements and prevention of cancer and cardiovascular disease (VITAL) — N Engl J Med, 2019. Search PubMed (opens in a new tab)
- 2.Vitamin D and type 2 diabetes prevention (D2d) — N Engl J Med, 2019. Search PubMed (opens in a new tab)
Last revised . A grade is this entry's reading of the evidence, not medical advice.