Vitamin D2 vs D3 (2026): Which Should You Take?
Not medical advice — this summarizes published research; if you were prescribed vitamin D2, talk to your doctor before switching. Methodology.
Take D3, not D2 — for almost everyone. Head-to-head, D3 raises blood vitamin D more efficiently: a 2024 meta-analysis of 20 trials found D2 raised 25(OH)D about 40% less than D3, even with daily dosing (PMID 37865222), and D3 lasts longer in the body. D2 also raises blood levels; it is just less efficient per dose. Choose D2 mainly if it is the form your doctor prescribed. Vegan? Look for lichen-derived D3, not D2.
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What's below: the head-to-head evidence for D3's ~40% edge (and an honest caveat that part of that gap is a lab-assay artifact), what a large trial found for vitamin D, the NIH intake ranges and upper limit, and how to pick a product — including a vegan D3 that beats D2.
Head-to-Head Comparison
| Factor | Vitamin D2 | Vitamin D3 |
|---|---|---|
| Chemical name | Ergocalciferol | Cholecalciferol |
| Source | UV-irradiated yeast/fungi (vegan) | Lanolin (sheep wool), or lichen (vegan); made in skin from sunlight |
| Raising blood 25(OH)D | Raises 25(OH)D, but less per dose | More efficient — ~40% more than D2 in daily-dose trials (PMID 37865222) |
| Half-life | Shorter — cleared faster | Longer — steadier blood levels (PMID 17023693) |
| Natural to humans? | No — humans don't make D2 | Yes — your skin makes D3 from UVB |
| High-dose form | 50,000 IU (Rx Drisdol) | Up to 50,000 IU (OTC & Rx) |
| Vegan? | Yes | Lichen-derived D3 is vegan; most other D3 (lanolin) is not |
| Bottom line | Fine if prescribed; less efficient | The usual choice for daily use |
The Evidence: Why D3 Is the Better Daily Choice
Multiple independent analyses reach the same conclusion — D3 raises serum 25-hydroxyvitamin D (the standard measure of vitamin D status) more than D2 at the same dose:
- A 2024 meta-analysis of 20 randomized trials found D2 raised total 25(OH)D about 10 nmol/L (~40%) less than D3, and importantly this held even with daily dosing — BMI was the strongest modifier, with the gap narrowing in heavier people (van den Heuvel 2024, PMID: 37865222).
- A separate 2021 meta-analysis (24 studies) reached the same verdict — D3 superior for total 25(OH)D by ~15.7 nmol/L (Balachandar 2021, PMID: 34684328) — and a 2017 daily-dosing RCT confirmed D3's edge specifically for everyday supplementation (Tripkovic 2017, PMID: 28679555), resolving an older question about whether D3's advantage held for daily (not just single large) doses.
- The likely mechanism: D2's metabolites bind vitamin D-binding protein less tightly, so D2 is cleared faster and produces a shorter, lower response (Houghton & Vieth 2006, PMID: 17023693 — a mechanistic review, not a trial).
One honest wrinkle worth knowing. Some clinical labs use blood tests that under-read the D2 metabolite, which can make D2 look even weaker than it truly is in real-world lab data (Garnett 2019, PMID: 31428669). The controlled trials above (using precise methods) still show a real D3 advantage — the point is just that the raw size of the gap can be partly an assay artifact, not only biology.
What a Large Trial Found
Large trials have not shown disease-prevention benefits. The large VITAL trial (25,000+ adults on D3 2,000 IU/day for ~5 years) found no reduction in cancer or major cardiovascular events (PMID: 30415629). Older pooled data hinted D3 (but not D2) might lower all-cause mortality (Cochrane 2014, PMID: 24414552), but that comes from pooling separate D2 and D3 trials — not a head-to-head test — so treat it as an open question, not a settled reason to pick D3. The case for D3 on this page rests on how much it raises blood 25(OH)D per dose.
NIH Intake Ranges
| Range | Amount | Notes |
|---|---|---|
| RDA | 600 IU/day (800 IU/day over 70) | Intake that covers most healthy adults |
| NIH tolerable upper limit | 4,000 IU/day | Higher only with testing/clinician guidance |
Get tested. Unlike magnesium (where blood tests are unreliable), the vitamin D blood test [25(OH)D] is accurate and widely available. The IOM used ≥20 ng/mL as its benchmark (some experts prefer 30+) (IOM/Ross 2011, PMID: 21118827). A simple blood draw shows your level. Ask a clinician what it means for you.
More isn't better — respect the upper limit. Chronic intake well above 4,000 IU/day can cause vitamin D toxicity: a buildup of calcium in the blood (hypercalcemia) that causes nausea, excessive thirst and urination, weakness, and, over time, kidney stones or damage. Don't go above 4,000 IU/day without a blood test and clinician guidance, and retest your 25(OH)D before continuing a high dose. Because D2 and D3 doses are easy to mix up, double-check which one you're taking so you don't accidentally stack them.
Picking a D3 Product
Cost per day comes from our product catalog. For a specific goal:
- 2,000 IU: Nature Made Vitamin D3 2000 IU ($0.06/day) — simple and inexpensive.
- 5,000 IU (above the NIH upper limit; ask a clinician): Nature Made Vitamin D3 5000 IU ($0.08/day) — one softgel.
- Vegan: Garden of Life Organics Vegan D3 Spray (1000 IU) ($0.14/day) — lichen-derived D3 (not D2), so you keep D3's efficiency.
See all seven ranked in our best vitamin D guide.
What About K2?
Some D3 products bundle vitamin K2 (menaquinone-7, MK-7). High-dose vitamin D increases calcium absorption, and the theory behind pairing is that K2 affects how calcium is handled; that is not proven by the trials cited here. K2 can interact with warfarin, so ask a clinician first.
See our detailed guide on vitamin D + K2.
Frequently Asked Questions
Is vitamin D2 or D3 better?
D3, for most people — it raises blood 25(OH)D more efficiently (D2 was ~40% lower in a 2024 meta-analysis of 20 trials, even daily; PMID: 37865222) and lasts longer in the body. D2 also raises blood levels; it is just less efficient. Take D3 unless D2 is the form your doctor prescribed.
Is there a vegan form of vitamin D3?
Yes — lichen-derived D3 is plant-based and the same cholecalciferol molecule, so you keep D3's efficiency over D2. That removes the old "take D2 if vegan" reason (D2 is also vegan, just less efficient).
What did the largest vitamin D trial find?
The large VITAL trial (25,871 adults, D3 2,000 IU/day) reported no reduction in cancer or major cardiovascular events compared with placebo (PMID: 30415629).
How much vitamin D3 should I take?
RDA 600 IU (800 over 70); the IOM used ≥20 ng/mL as its sufficiency benchmark (PMID: 21118827). Upper limit 4,000 IU/day without clinician guidance.
Related Guides
- Vitamin D Dosage Guide — NIH intake ranges
- Should You Take D3 with K2? — what the research does and does not show
- Best Vitamin D Supplement — 7 products ranked
- Vitamin D Deficiency Signs · All Vitamin D Guides
Sources
- van den Heuvel EG, et al. "Comparison of the Effect of Daily Vitamin D2 and Vitamin D3 Supplementation on Serum 25-Hydroxyvitamin D Concentration: Systematic Review and Meta-Analysis." Adv Nutr. 2024;15(1):100133. PMID: 37865222
- Balachandar R, et al. "Relative Efficacy of Vitamin D2 and Vitamin D3 in Improving Vitamin D Status: Systematic Review and Meta-Analysis." Nutrients. 2021;13(10):3328. PMID: 34684328
- Tripkovic L, et al. "Daily supplementation with 15 µg vitamin D2 compared with vitamin D3... a 12-wk randomized food-fortification trial." Am J Clin Nutr. 2017;106(2):481-490. PMID: 28679555
- Tripkovic L, et al. "Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis." Am J Clin Nutr. 2012;95(6):1357-1364. PMID: 22552031
- Houghton LA, Vieth R. "The case against ergocalciferol (vitamin D2) as a vitamin supplement." Am J Clin Nutr. 2006;84(4):694-697. PMID: 17023693
- Garnett E, et al. "Efficacy of two vitamin D immunoassays to detect 25-OH vitamin D2 and D3." Pract Lab Med. 2019;17:e00130. PMID: 31428669
- Durrant LR, et al. "Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System." Front Immunol. 2022;13:790444. PMID: 35281034
- Bjelakovic G, et al. "Vitamin D supplementation for prevention of mortality in adults." Cochrane Database Syst Rev. 2014;(1):CD007470. PMID: 24414552
- Manson JE, et al. "Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease (VITAL)." N Engl J Med. 2019;380(1):33-44. PMID: 30415629
- Ross AC, et al. "The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine." J Clin Endocrinol Metab. 2011;96(1):53-58. PMID: 21118827
- NIH Office of Dietary Supplements. "Vitamin D: Fact Sheet for Health Professionals." ods.od.nih.gov