Vitamin D2
Useful mainly for correcting documented vitamin D deficiency, especially where a vegan form is needed.
Quick decision guide
May help most
Correcting documented vitamin D deficiency, especially where a vegan form is needed
Common dosing range
600–800 IU/day RDA; 50,000 IU weekly (prescription) for deficiency
When to expect effects
Weeks to raise blood levels
Watch out for
Chronic high-dose use without monitoring can cause hypercalcemia
What is it
Vitamin D2, also called ergocalciferol, is a plant-derived form of vitamin D produced commercially by irradiating yeast or fungi. It is the form used in most prescription high-dose vitamin D and many vegan supplements.
Is it worth it for you?
Use this as a quick fit check, not a diagnosis.
Worth considering if…
Probably skip if…
Evidence at a glance
| Goal | Effect | Best fit | Time |
|---|---|---|---|
treatment of vitamin d deficiency Strong Evidence | Reliable repletion of stores | People with documented low 25(OH)D | Weeks |
bone health support Good Evidence | Modest, mainly with adequate calcium and in deficiency | Older or deficient adults, typically with calcium | Months |
raising serum 25(oh)d Good Evidence | Raises 25(OH)D, less per dose than D3 | People needing to increase measured vitamin D status | Weeks |
treatment of vitamin d deficiency
- Effect
- Reliable repletion of stores
- Best fit
- People with documented low 25(OH)D
- Time
- Weeks
bone health support
- Effect
- Modest, mainly with adequate calcium and in deficiency
- Best fit
- Older or deficient adults, typically with calcium
- Time
- Months
raising serum 25(oh)d
- Effect
- Raises 25(OH)D, less per dose than D3
- Best fit
- People needing to increase measured vitamin D status
- Time
- Weeks
Evidence for 3 uses
AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.
treatment of vitamin d deficiency
Corrects deficiencyVitamin D2 is hydroxylated to 25-hydroxyvitamin D2 and then to the active hormone, binding the vitamin D receptor to support calcium absorption and bone mineralization. High-dose D2 (commonly 50,000 IU weekly) reliably corrects documented deficiency and is the basis of standard prescription repletion. D2 raises serum levels somewhat less efficiently than D3 at equal doses, so monitoring helps confirm repletion.
Bottom line: Effective, well-established treatment for documented vitamin D deficiency.
bone health support
Supplement benefitBy supporting calcium absorption and mineralization, vitamin D contributes to bone health, with the clearest benefit in deficient or older populations and when combined with adequate calcium. Trials in already-replete people show limited additional benefit. D2 and D3 are largely interchangeable for this purpose, though D3 is generally preferred.
Bottom line: Supports bone health mainly in deficient or older adults, especially alongside calcium.
Evidence is mixed
Benefits are clear in deficiency but inconsistent in replete populations, where supplementation adds little.
raising serum 25(oh)d
Biomarker supportVitamin D2 raises serum 25-hydroxyvitamin D, but it binds vitamin D binding protein less tightly and clears faster, so it increases measured levels less effectively than D3 at the same dose. This is a blood-level (biomarker) effect; the clinically meaningful goal is correcting deficiency rather than the number itself. Where maximizing 25(OH)D per dose matters, D3 is usually preferred.
Bottom line: Raises measured vitamin D levels, but less efficiently than D3 per dose.
How it works
How to take it
What to track
Safety
Know the common side effects, key cautions, and who should avoid it.
Common side effects
Serious risks
Hypercalcemia with chronic high-dose use (nausea, weakness, frequent urination, kidney stones, arrhythmia in severe cases)
Who should avoid it
- People with kidney disease
- Hyperparathyroidism
- Sarcoidosis or other granulomatous diseases (without medical guidance)
Pregnancy & breastfeeding
Same RDA as other adults; high-dose use should be supervised.
Interactions
Reduce calcium absorption and impair vitamin D action
Reduces vitamin D absorption; separate dosing
Reduce vitamin D absorption; separate dosing
Combined with high-dose vitamin D can raise calcium excessively
Reduce vitamin D activity
Food sources
| Food | Amount | %DV |
|---|---|---|
| Mushrooms exposed to UV light, 1/2 cup | 366 IU (9.2 mcg) | 46% |
| Fortified plant milk, 1 cup | 100 to 120 IU | 15% |
Mushrooms exposed to UV light, 1/2 cup
- Amount
- 366 IU (9.2 mcg)
- %DV
- 46%
Fortified plant milk, 1 cup
- Amount
- 100 to 120 IU
- %DV
- 15%
Choosing a product
What to look for on the label — and what to be skeptical of.
Look for…
Be skeptical of…
Frequently asked questions
Is D2 as effective as D3?⌄
Both raise vitamin D status, but D3 is generally more potent dose-for-dose. For most people D3 is the better choice unless they need a vegan or prescription option.
Why do doctors prescribe D2 instead of D3?⌄
Prescription D2 has been available longer in the U.S. in high-dose form (50,000 IU capsules), so many physicians default to it. High-dose D3 is increasingly available too.
Is vitamin D2 vegan?⌄
Yes. D2 is made from yeast or fungi exposed to UV light and is suitable for vegan diets.
How often do I take prescription 50,000 IU D2?⌄
Most regimens are once weekly for 8 to 12 weeks to correct deficiency, then a lower maintenance dose. Follow your prescriber's instructions and get blood levels rechecked.
References by claim
Track Vitamin D2 with Pilora
Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.
Coming to App StoreDisclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.