Vitamin D

Is vitamin D3 better than vitamin D2?

Updated 3 Nov 2026

Short answer

For raising the blood level, yes. In a 2024 review, in 12 comparisons of daily doses, vitamin D2 raised total 25(OH)D by about 10 nmol/L, or 40%, less than vitamin D3.[1] Both forms are well absorbed, and they seem to cure rickets equally well.[2]

What the two forms are

Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) differ only in one part of the molecule, the side chain.[2] Most steps of how the body activates and uses them are the same.[2]

  • D2 is made by shining UV light on a compound from yeast. Mushrooms treated with UV light also contain D2.[2]
  • D3 is the form the skin makes. Supplements make it from lanolin, the fat of sheep's wool. A vegan D3 from lichen is also sold.[2]
  • Beef liver, egg yolks and cheese contain small amounts, mostly as D3.[2]

What the trials found

A 2012 review of trials that compared the two forms found that D3 raised the blood level of 25(OH)D more than D2.[3] The difference was clear when people took one large dose. With daily doses, that review found no clear difference.[3]

A 2024 review looked again at daily and weekly doses, in 20 trials that compared the forms. D3 still raised total 25(OH)D more.[1] In 12 daily comparisons measured with the same lab method (liquid chromatography-tandem mass spectrometry), the rise with D2 was 10.39 nmol/L smaller. That is 40% less than with D3.[1]

The NIH Office of Dietary Supplements comes to the same view. D3 raises the blood level more and keeps it high for longer, although the gut absorbs both forms well.[2]

Body weight changes the difference

In the 2024 review, body mass index (BMI) explained most of the differences between trials.[1] In people with a BMI above 25, the difference between D2 and D3 was no longer significant.[1] People with obesity may need more vitamin D of either form to reach the same blood level, because body fat holds on to it.[2]

Each form raises its own 25(OH)D

The liver turns D2 into 25(OH)D2 and D3 into 25(OH)D3. In the 2024 review, each form raised its own type by a similar amount. The difference was in the total.[1]

A third form: calcifediol

Some studies used 25(OH)D3 itself, also called calcifediol.[4] Per microgram, it is 3 to 5 times as strong as vitamin D3 at raising the blood level.[2] For food labels in the EU, EFSA proposed counting 1 µg of calcifediol monohydrate as 2.5 µg of vitamin D3.[4] According to NIH ODS, no calcifediol supplements appear to be sold to consumers in the US.[2]

What is still unknown

The two reviews measured blood levels, not health outcomes such as fractures or infections.[3][1] Whether a higher blood level from D3 also means a better health result is not known from these trials.[1] The EU upper limit of 100 µg a day for adults counts D2, D3 and calcifediol together.[4]

Sources (4)

  1. Comparison of the Effect of Daily Vitamin D2 and Vitamin D3 Supplementation on Serum 25-Hydroxyvitamin D Concentration (Total 25(OH)D, 25(OH)D2, and 25(OH)D3) and Importance of Body Mass Index: A Systematic Review and Meta-Analysis. van den Heuvel EG, Lips P, Schoonmade LJ, Lanham-New SA, van Schoor NM Adv Nutr, 2024. PMID 37865222
  2. Vitamin D: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  3. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Tripkovic L, Lambert H, Hart K, Smith CP, Bucca G, Penson S, et al. Am J Clin Nutr, 2012. PMID 22552031
  4. Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) European Food Safety Authority, 2023. efsa.onlinelibrary.wiley.com

More about vitamin d

What is vitamin D?How do you get vitamin D from sunlight and food?What is vitamin D used for?What vitamin D blood level is too low?Is vitamin D safe?Does vitamin D prevent fractures?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.