Comparison

Vitamin D2 vs D3: What the Research Shows

By LongevityBeginners Editorial Team · Last reviewed Nov 3, 2026

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Vitamin D comes in two common forms, D2 and D3. Most supplements use D3. This page explains what two reviews of head-to-head trials found, and what they do not tell you. For everything else about vitamin D, see our vitamin D guide, and for products see best vitamin D supplements.

Side by side

	Vitamin D2 The other common form of vitamin D	Vitamin D3 (cholecalciferol) The form most supplements use
What it is	One of the two common supplement forms of vitamin D.	The most common supplement form (cholecalciferol).
Effect on blood vitamin D (25(OH)D)	Raised blood levels less than D3 in two reviews of head-to-head trials.	Raised blood levels more than D2 in a 2012 review of randomized trials and in a 2024 review of 20 comparative studies.
Size of the difference	In 12 daily-dose comparisons, about 10 nmol/L (40%) lower than D3 in the 2024 review.	The 2012 review found the difference was lost with daily dosing; the 2024 review found it held for daily doses, but it lost significance in people with a BMI over 25.
Evidence for health outcomes	These reviews measured blood levels, not health outcomes.	Same. Big trials in generally healthy adults mostly found no clear extra benefit of vitamin D (see our guide).
Typical cost (per 10 µg)	From $0.040 (US, NOW capsule) to £0.322 (UK, Viridian capsule) per 10 µg, checked Nov 3, 2026.	From $0.020 (US, NOW softgel) to $0.0756 (US, Thorne capsule) per 10 µg, checked Nov 1 to 3, 2026.
Who might prefer it	We found no evidence on who should choose D2, so we make no claim.	Most beginners, because it is the common form and did better on blood levels.

Our verdict

Best for most beginners: Vitamin D3 (cholecalciferol)

On blood levels, D3 did better than D2 in two reviews of head-to-head trials, which is why D3 is the common supplement form. A higher blood level is a lab marker, so this does not show that D3 improves health more than D2. Check the amount in micrograms (and IU) and ask a doctor or pharmacist about the dose that suits you.

Where to buy

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United States

US Thorne Vitamin D-1,000, 90 capsules at Thorne – $17.00 · $0.076 per daily dose (per 10 µg (400 IU) vitamin D) (price checked on Nov 1, 2026) – third-party testing: None named in our data – for: Vitamin D3 (cholecalciferol) – Vitamin D3, 25 µg (1,000 IU) per capsule, $0.0756 per 10 µg (checked Nov 1, 2026)
US NOW Vitamin D3 1000 IU Softgels (180 or 360 count) at NOW Foods – $8.99 · $0.020 per daily dose (per 10 µg (400 IU) vitamin D) (price checked on Nov 3, 2026) – third-party testing: None named in our data – for: Vitamin D3 (cholecalciferol) – Vitamin D3, 25 µg (1,000 IU) per softgel, 180 softgels, $0.020 per 10 µg (checked Nov 3, 2026)
US NOW Foods Vitamin D2 1,000 IU (dry), 120 veg capsules at NOW Foods – $11.99 · $0.040 per daily dose (per 10 µg (400 IU) vitamin D) (price checked on Nov 3, 2026) – third-party testing: None named in our data – for: Vitamin D2 – Vitamin D2 (ergocalciferol), 25 µg (1,000 IU) per vegan capsule, $0.040 per 10 µg (checked Nov 3, 2026)
US NOW Foods Vitamin D2 1,000 IU (dry), 120 veg capsules at Amazon.com – $7.33 · $0.024 per daily dose (per 10 µg (400 IU) vitamin D) (price checked on Nov 3, 2026) – third-party testing: None named in our data – for: Vitamin D2

Worldwide

Intl Check price at iHerb – NOW Foods Vitamin D2 1,000 IU (dry), 120 veg capsules – third-party testing: None named in our data – for: Vitamin D2

United Kingdom

UK Viridian Organic Vitamin D2 400 IU, 60 vegan capsules at vits4you – £19.29 · £0.32 per daily dose (per 10 µg (400 IU) vitamin D) (price checked on Nov 3, 2026) – third-party testing: None named in our data – for: Vitamin D2 – Vitamin D2 from organic mushrooms, 400 IU (10 µg) per capsule per the product title, £0.322 per 10 µg (checked Nov 3, 2026). The label table was not shown on the page, so check the label

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What the reviews found

2012 review. A systematic review and meta-analysis of randomized trials that directly compared the two forms found that D3 raised blood 25-hydroxyvitamin D [25(OH)D], the usual blood measure of vitamin D status, more than D2. In that review the difference was seen with single large doses but was lost with daily supplementation. Source: Tripkovic L et al., Am J Clin Nutr, 2012 (PubMed · DOI).

2024 review. A newer meta-analysis of 20 comparative studies found D3 raised total 25(OH)D more than D2, even when it looked only at daily doses. In 12 daily-dose comparisons, the D2 group’s rise was about 10 nmol/L (40%) lower. The difference lost significance mainly in people with a BMI above 25. Source: van den Heuvel EG et al., Adv Nutr, 2024 (PubMed · DOI).

What this does not tell you

Both reviews measured a blood level. A blood level is a lab marker, not a health outcome such as bone health. Our vitamin D guide covers the outcome trials, which in generally healthy adults have mostly found no clear extra benefit.

Amounts

US guidance sets 15 micrograms (600 IU) a day for most adults. The NHS advises considering 10 micrograms (400 IU) a day in fall and winter (October to early March in the UK). The NHS and the NIH both set an upper limit of 100 micrograms (4,000 IU) a day for adults, and limits for babies and children are lower.

Check which form is on the label

Labels do not always say. For example, a Holland & Barrett 10 µg tablet in our product data lists only “Vitamin D” in its ingredients, so we have not counted it as D2 or D3. Look for “D2 (ergocalciferol)” or “D3 (cholecalciferol)” on the pack.

Talk to your doctor or pharmacist

Talk to your doctor or pharmacist before you start any supplement, especially if you are pregnant or breastfeeding, take prescription medicine, or have a health condition. Limits for babies and children are lower, so ask before giving a supplement to a child.

FAQ

Is vitamin D3 better than D2?

On raising blood vitamin D levels, D3 did better in two reviews of head-to-head trials. That is a lab marker, so it does not prove D3 gives better health results.

Which form do most supplements use?

Most supplements use D3 (cholecalciferol).

Should I take vitamin D with K2?

We found no trial in our sources testing the pairing. See our vitamin K2 guide for what the research shows for K2 itself.

How much vitamin D should I take?

US guidance sets 15 micrograms (600 IU) a day for most adults, and the NHS advises considering 10 micrograms (400 IU) a day in fall and winter. The upper limit for adults is 100 micrograms (4,000 IU) a day. Ask a doctor or pharmacist what suits you.