Vitamin D2 and D3 can both raise vitamin D levels, but vitamin D3 generally raises serum 25-hydroxyvitamin D more effectively and tends to maintain those increases longer. D2, or ergocalciferol, is commonly derived from fungi or yeast, while D3, or cholecalciferol, is commonly sourced from lanolin and can also come from lichen. For many supplement users, D3 is the practical first choice unless dietary preferences, availability, or clinical guidance favor D2.
Key Takeaways
- Vitamin D2 is ergocalciferol; vitamin D3 is cholecalciferol.
- Both forms are absorbed in the intestine and can raise serum 25-hydroxyvitamin D.
- Most comparative evidence finds that D3 raises total 25-hydroxyvitamin D more than D2 and maintains the increase longer.
- D2 is commonly produced from UV-treated fungal or yeast sources, while D3 is often derived from lanolin; lichen-derived vegan D3 is also available.
- Neither form should be taken in unnecessarily high doses because excessive vitamin D can cause toxicity.
What Is the Difference Between Vitamin D2 and D3?
Vitamin D is a fat-soluble vitamin that supports calcium metabolism, bone health, neuromuscular function, and other biological processes. The two main forms found in foods and supplements are vitamin D2 and vitamin D3.
Vitamin D2 is called ergocalciferol. Vitamin D3 is called cholecalciferol. Their chemical structures differ slightly in the side chain, but their metabolism follows many of the same steps after absorption.
Both forms can ultimately contribute to the body’s pool of 25-hydroxyvitamin D, commonly written as 25(OH)D. This circulating metabolite is the main laboratory marker used to assess vitamin D status.
The important practical difference: D2 and D3 both work as vitamin D sources, but D3 generally produces a larger and more sustained rise in total circulating 25(OH)D.
Vitamin D2 vs D3 at a Glance
| Feature | Vitamin D2 | Vitamin D3 |
|---|---|---|
| Chemical name | Ergocalciferol | Cholecalciferol |
| Typical supplement source | UV-treated yeast or fungal ergosterol | Lanolin or, in some products, lichen |
| Raises 25(OH)D? | Yes | Yes |
| Relative effect on total 25(OH)D | Usually smaller | Usually larger |
| Vegan availability | Commonly suitable | Available when sourced from lichen; check the label |
Is Vitamin D3 Better Than D2?
If the goal is to raise total serum 25(OH)D efficiently, the balance of evidence favors vitamin D3. NIH guidance states that both D2 and D3 raise 25(OH)D, but D3 generally raises it to a greater extent and maintains higher levels for longer.
A systematic review and meta-analysis including 24 studies and 1,277 participants found that D3 was more effective than D2 at improving total 25(OH)D. The analysis also found a greater reduction in parathyroid hormone with D3.
A separate 2023 systematic review focusing on daily or frequently administered doses likewise concluded that D3 produced a greater rise in total 25(OH)D than D2. Results varied between individuals and studies, but the overall direction favored D3.
This does not make D2 ineffective: D2 can meaningfully raise vitamin D status. D3 simply tends to produce a stronger or more sustained response at comparable intakes.
Why Might D3 Raise Vitamin D Levels More?
D2 and D3 are absorbed well from the intestine, so the difference is not simply that one form is absorbed and the other is not. Differences emerge in how the two forms are transported, metabolized, converted to their 25-hydroxylated forms, and cleared from the circulation.
Older pharmacokinetic studies found that circulating vitamin D metabolites derived from D3 can persist longer than those derived from D2. This helps explain why D3 can produce a more sustained increase in total vitamin D status over time.
The difference is most useful as a population-level comparison. Individual responses still vary according to baseline vitamin D status, body size, supplement dose, adherence, dietary intake, and other factors.
Where Does Vitamin D2 Come From?
Vitamin D2 is associated mainly with fungal sources. Mushrooms naturally contain variable amounts of D2, and exposing certain mushrooms to ultraviolet light can substantially increase their vitamin D2 content.
Commercial vitamin D2 used in supplements is commonly produced by exposing ergosterol from yeast to ultraviolet radiation. Because this source does not require animal-derived lanolin, D2 has historically been a common choice for vegan vitamin D supplements.
Where Does Vitamin D3 Come From?
Vitamin D3 is the form produced in human skin when ultraviolet B radiation acts on 7-dehydrocholesterol. It is also the predominant parent form found in many animal-derived foods.
Most conventional D3 supplements are manufactured from lanolin obtained from sheep’s wool. However, animal-free vitamin D3 derived from lichen is also available, which means people following vegan diets do not necessarily have to choose D2.
Check the source, not just “D3”: A D3 supplement may come from lanolin or lichen. The label or manufacturer can clarify whether a product fits a vegan dietary pattern.
Food Sources of D2 and D3
Only a limited number of foods naturally contain substantial vitamin D. Fatty fish and fish liver oils are among the richest natural dietary sources, while egg yolks, liver, and cheese provide smaller amounts primarily in forms related to vitamin D3.
Mushrooms can provide vitamin D2, especially when exposed to ultraviolet light. In the United States, fortified foods such as milk, plant-based beverages, cereals, and some other products also contribute significantly to vitamin D intake, although the form used for fortification can differ by product.
The Nutrition Facts panel shows the total vitamin D content rather than necessarily emphasizing whether the added vitamin is D2 or D3, so ingredient lists can be useful when the form matters to you.
How Much Vitamin D Do Adults Need?
U.S. Dietary Reference Intakes recommend 15 micrograms, or 600 IU, of vitamin D per day for adults through age 70. For adults older than 70, the RDA is 20 micrograms, or 800 IU, per day. These reference values assume minimal sun exposure.
These values describe general nutritional requirements for healthy populations. They are not individualized treatment doses for someone with a diagnosed deficiency, malabsorption disorder, osteoporosis, or another medical indication.
The 2024 Endocrine Society guideline also advises generally healthy adults under age 75 against routinely taking vitamin D above established reference intakes solely for disease prevention.
Should Everyone Test Their Vitamin D Level?
Routine vitamin D blood testing is not recommended for every healthy adult. The 2024 Endocrine Society guideline suggests against routine 25(OH)D screening in several generally healthy populations when there is no established clinical indication for testing.
Testing can still be appropriate when a clinician is evaluating a specific medical issue, such as abnormal calcium metabolism or another condition in which vitamin D status directly affects diagnosis or treatment.
If you have been prescribed vitamin D to correct a documented deficiency, the choice between D2 and D3 should be interpreted within that treatment plan rather than changed solely because one form performs better on average.
Does Vitamin D Need to Be Taken With Food?
Vitamin D is fat soluble. NIH guidance notes that the presence of fat in the intestine can enhance absorption, although vitamin D is still absorbed without dietary fat.
Taking a vitamin D supplement with a meal or snack that contains some fat is therefore a simple practical strategy. Consistency also matters, so the best time may be whichever meal helps you remember the supplement regularly.
Is D2 a Good Option for Vegans?
Yes. Vitamin D2 is generally produced from non-animal fungal or yeast sources and has long been used in vegan supplements and fortified foods.
However, vegans are no longer limited to D2. Lichen-derived vitamin D3 provides an animal-free D3 option, allowing people who prefer D3’s generally stronger effect on serum 25(OH)D to choose it without using a lanolin-derived product.
Can You Take Too Much Vitamin D?
Yes. Vitamin D is fat soluble, and excessive supplemental intake can cause toxicity. The main problem is an abnormally high calcium level in the blood and urine, which can lead to symptoms and complications involving the kidneys, cardiovascular system, and other tissues.
For adults, the U.S. Tolerable Upper Intake Level is 100 micrograms, or 4,000 IU, per day from all sources unless a clinician is using a different dose as part of medically supervised treatment.
The upper limit is not a recommended daily target. It represents an intake level above which the risk of adverse effects becomes a greater concern.
Do not confuse potency with permission to megadose: Choosing D3 because it tends to raise 25(OH)D more efficiently does not mean that higher and higher doses are beneficial.
Vitamin D and Medication Interactions
Vitamin D supplements can interact with medications, and some medications can affect vitamin D metabolism or absorption. NIH guidance highlights examples including orlistat, corticosteroids, certain statins, and thiazide diuretics.
Thiazide diuretics deserve particular attention because combining them with vitamin D can increase the risk of high calcium levels in some people, especially those with impaired kidney function or hyperparathyroidism.
Check before supplementing: If you take prescription medications regularly or have kidney, parathyroid, or calcium-related conditions, discuss vitamin D supplements with your healthcare professional.
How to Choose Between Vitamin D2 and D3
For an over-the-counter supplement, D3 is generally the straightforward choice when the goal is to efficiently maintain vitamin D status. The preference is based primarily on its stronger average effect on total serum 25(OH)D rather than on D2 being inactive or unsafe.
- Choose D3 if you want the form with the strongest overall evidence for raising and maintaining total 25(OH)D.
- Choose D2 if it fits your dietary preferences, availability, or clinician-directed treatment.
- Choose lichen-derived D3 if you want D3 while avoiding animal-derived lanolin.
- Check the dose rather than assuming more is better.
- Follow clinical guidance if you are treating a diagnosed deficiency or another medical condition.
Frequently Asked Questions
Related reading
The Bottom Line
Vitamin D2 and D3 are both legitimate forms of vitamin D, and both can raise circulating 25(OH)D. The main practical difference is potency over time: vitamin D3 generally produces a greater and more sustained increase in vitamin D status, which makes it a reasonable default choice for many over-the-counter supplements.
D2 remains useful, particularly when it fits dietary preferences or a clinician-directed treatment plan. Whichever form you choose, pay attention to the total dose, avoid unnecessary megadosing, and seek individualized advice when deficiency, medications, kidney disease, calcium disorders, or other medical issues affect vitamin D management.
Medical disclaimer
Medical disclaimer: This content is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Dietary needs and supplement suitability vary by individual.
Sources
- National Institutes of Health, Office of Dietary Supplements. Vitamin D: Health Professional Fact Sheet. Accessed September 2026.
- Demay MB, Pittas AG, Bikle DD, et al. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2024.
- Balachandar R, Pullakhandam R, Kulkarni B, Sachdev HS. Relative Efficacy of Vitamin D2 and Vitamin D3 in Improving Vitamin D Status: Systematic Review and Meta-Analysis. Nutrients. 2021.
- Comparison of the Effect of Daily Vitamin D2 and Vitamin D3 Supplementation on Serum 25-Hydroxyvitamin D Concentration and Importance of Body Mass Index: A Systematic Review and Meta-Analysis. Advances in Nutrition. 2023.
- 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. American Journal of Clinical Nutrition. 2012.
