Evidence brief · Supplement
Vitamin D for Correcting deficiency (25(OH)D)
Evidence grade A — Dose-dependent, predictable rise
- Overall grade
- Grade A
- Last revised
- 1
- graded outcome
- 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.
1 at grade A — 1 graded row
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Correcting deficiency (25(OH)D)Evidence grade A
Dose-dependent, predictable rise
Largehigh
The evidence in words
The verdict
For correcting deficiency (25(oh)d), Vitamin D earns evidence grade A (large effect, high consistency) — there is real evidence here. Dose-dependent, predictable rise
How it might work
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.
How to use it
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.
Safety & cautions
Very safe in the ordinary range; toxicity (hypercalcemia) is real but requires sustained megadosing, typically well above 10,000 IU/day for months. The classic mistake is high-dose D without magnesium (a required cofactor) or K2 (which directs calcium to bone rather than arteries).
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 DRead the full Vitamin D monographEvidence grade A
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 Fracture / fall risk (deficient elderly + calcium)Evidence grade B — Benefit concentrates in the deficient and institutionalizedEvidence grade B
- Vitamin D for Osteoporosis / bone lossEvidence grade B — With calcium, in deficiencyEvidence 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.