Vitamin D comes in two main supplement forms, D2 and D3, and labels don't always explain the difference. Both work. But if you're choosing between them, the research leans in one direction.
Written by Vita Globe Editorial Team | Reviewed against NIH guidance, a systematic review and meta-analysis, and randomized trials
Is vitamin D3 better than D2?
Both forms raise blood vitamin D, but most evidence shows D3 raises levels more and keeps them higher for longer than D2[1]. A 2012 meta-analysis of randomized trials found D3 more effective overall, with the clearest difference when vitamin D was given in large, infrequent doses[2]. With small daily doses, the gap is smaller and some trials found no difference[3].
Caveat: Prescription vitamin D in the U.S. is often D2, and it works when used as directed. Don't switch a prescribed regimen without asking your doctor.
Sources: NIH ODS · Tripkovic et al., AJCN 2012 · Holick et al., JCEM 2008 · Verified 2026-09-27
IN THIS ARTICLE
What's the difference between D2 and D3?
Vitamin D2 (ergocalciferol) is made by plants and fungi, such as mushrooms exposed to UV light. Vitamin D3 (cholecalciferol) is the form your skin makes from sunlight and the form found in animal foods like fatty fish and egg yolks[1].
Both are inactive until your liver converts them into 25-hydroxyvitamin D and your body then activates them. Both appear in dietary supplements and fortified foods[1].
| Vitamin D2 | Vitamin D3 | |
|---|---|---|
| Chemical name | Ergocalciferol | Cholecalciferol |
| Natural sources | UV-exposed mushrooms, yeast | Skin exposed to sun, fatty fish, egg yolks |
| Raising blood levels | Works, generally less potent | Generally raises and sustains levels better |
| Vegan options | Yes | Yes, from lichen |
What does the research say?
The NIH summary is that most evidence shows D3 raises blood 25(OH)D more and maintains it longer than D2[1].
The strongest single piece of evidence is a systematic review and meta-analysis of randomized trials in the American Journal of Clinical Nutrition. It found D3 was more effective overall at raising blood levels. The advantage was most pronounced when vitamin D was given as large, infrequent doses, and less clear with daily dosing[2].
A classic single-dose study makes the point more dramatically. When healthy men took one 50,000 IU dose of either form, D2 was less than one-third as potent as D3 over the following four weeks[4].
Not every study agrees, which is why we'd call this a lean rather than a slam dunk. An 11-week winter trial found that 1,000 IU a day of D2 raised blood levels as much as 1,000 IU of D3[3]. Researchers who favor D3 also point to differences in how the two forms are metabolized and how long they stay in circulation[5].
The honest summary
- Both D2 and D3 raise vitamin D levels[1].
- D3 is generally more effective, especially at high, infrequent doses[2][4].
- At modest daily doses, the difference may be small[3].
So which should you choose?
For an everyday, over-the-counter supplement, D3 is the reasonable default given the evidence[1][2]. It's the form your body makes naturally, and it's what VITAL, one of the largest vitamin D trials, used at 2,000 IU a day[6].
If your doctor prescribed high-dose D2 to treat a deficiency, stick with the plan and ask before changing forms. Prescribed regimens come with follow-up testing, so your doctor will see whether it's working.
Is vitamin D3 vegan?
Traditionally, D3 in supplements came from lanolin (sheep's wool), so vegans often chose D2. That's changed. The NIH notes that an animal-free vitamin D3 sourced from lichen is now available[1].
If you follow a vegan diet, check the label or the product page for a vegan claim rather than assuming either way. Food sources of vitamin D are limited for vegans, which is one reason a supplement often makes sense. Our vitamin D deficiency signs, causes and treatment guide covers who is most likely to run low.
For more on why the "D3 over D2" advice shows up so often, see our overview of why vitamin D matters.
Our option
Vita Globe Vitamin D3 2,000 IU Gummies
Each 2-gummy serving provides 2,000 IU (50 mcg) of vitamin D3, the form most research favors, in a strawberry-flavored gummy that's vegan, gluten-free and non-GMO, and tested by an independent third-party lab.
Frequently asked questions
Is D3 the same as vitamin D?
D3 is one form of vitamin D. "Vitamin D" on a label can mean D2 or D3, so check the form[1].
Why do doctors prescribe D2 instead of D3?
High-dose prescription vitamin D in the U.S. is often D2, and it works when used as directed with follow-up testing. Ask your doctor before swapping forms.
Is D3 better absorbed than D2?
Both are absorbed. The difference is that D3 generally raises and keeps blood levels higher, particularly with large doses[1][2].
Is vitamin D3 vegan?
It can be. Lichen-sourced vitamin D3 is an animal-free option[1]. Check the product's labeling.
Can I take D2 and D3 together?
Yes, but count both toward your total. The adult upper limit is 4,000 IU a day from all sources[1].
Sources
- Office of Dietary Supplements, National Institutes of Health. Vitamin D: Fact Sheet for Health Professionals. Accessed September 27, 2026. ods.od.nih.gov/factsheets/VitaminD-HealthProfessional
- Tripkovic L, Lambert H, Hart K, 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. doi:10.3945/ajcn.111.031070
- Holick MF, Biancuzzo RM, Chen TC, et al. Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. J Clin Endocrinol Metab. 2008;93(3):677-681. doi:10.1210/jc.2007-2308
- Armas LAG, Hollis BW, Heaney RP. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin Endocrinol Metab. 2004;89(11):5387-5391. doi:10.1210/jc.2004-0360
- Houghton LA, Vieth R. The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr. 2006;84(4):694-697. doi:10.1093/ajcn/84.4.694
- Manson JE, Cook NR, Lee IM, et al. Vitamin D supplements and prevention of cancer and cardiovascular disease. N Engl J Med. 2019;380(1):33-44. doi:10.1056/NEJMoa1809944
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
