Vitamin D2 vs D3 comes down to source and staying power. D2 (ergocalciferol) comes from plants, yeast and mushrooms, and D3 (cholecalciferol) is the form your skin makes in sunlight and the form in fish and eggs. Both raise blood vitamin D, but in a pooled analysis of trials and in a 12-week trial of 335 women, D3 raised it more than the same amount of D2.
This guide compares the two forms: where each comes from, what the trials found, vegan D3, how to read the label and the upper limit. For the doses that worked and the side effects in the studies, see our vitamin D page; it lists the vitamin D products in our catalog too.
Vitamin D2 vs D3 at a Glance
| Vitamin D2 (ergocalciferol) | Vitamin D3 (cholecalciferol) | |
|---|---|---|
| Where it comes from | Plants, yeast and mushrooms exposed to UV light | Made in the skin in sunlight; oily fish, egg yolks; supplements from lanolin (sheep's wool) or, for vegan D3, lichen |
| Raising blood vitamin D | Raises it, but less than D3 | Raised blood vitamin D more than D2 in a pooled analysis of trials and in a 12-week trial of 335 women |
| Human studies we graded that name the form | 22 | 227 |
| Found in | Some fortified plant milks and cereals; UV-treated mushrooms | Most vitamin D supplements and multivitamins |
Taking a multivitamin too? Check whether you're doubling up on vitamin D.
What the Trials Found
A pooled analysis of the randomized trials that compared the two found D3 raised blood vitamin D (measured as 25-hydroxyvitamin D) more than D2. The gap was clearest when the vitamin was given as one large dose; with daily doses it was smaller (Tripkovic 2012).
A later trial tested the small daily amount found in fortified food. Over 12 winter weeks, 335 women aged 20 to 64 had 15 mcg (600 IU) a day of D2 or D3 in juice or a biscuit, or a placebo. D3 raised blood vitamin D more than D2 in both foods (Tripkovic 2017).
That is why most supplements use D3. Of the human studies of vitamin D we graded that name the form, 227 used D3 and 22 used D2. The page for each form shows its own studies: vitamin D3 and vitamin D2.
Vegan Vitamin D: D2 or Lichen D3
Most D3 is made from lanolin, the oil in sheep's wool, so it is not vegan. D2 has always been the vegan choice. D3 made from lichen is now sold as vegan D3, which gives plant-based eaters the form that raised blood levels more in the trials.
Reading the Label: IU and mcg
Labels give vitamin D in micrograms (mcg), international units (IU), or both: 1 mcg is 40 IU, so 25 mcg is 1,000 IU. The recommended amount for adults is 600 IU (15 mcg) a day, 800 IU over age 70, and the upper limit for adults is 4,000 IU (100 mcg) a day from all sources (Ross 2011). Our guide to safe upper limits shows how to add up vitamin D across a multivitamin and a separate D.
Take it with a meal. Vitamin D is absorbed with fat: in 50 older adults, D3 taken with a meal that contained fat reached a 32% higher peak in the blood than with a fat-free meal (Dawson-Hughes 2015). Our guide to the best time to take your vitamins covers timing.
If you take meds: some meds change how vitamin D is absorbed or used, and high doses add calcium to the blood. Check with your doctor or pharmacist before taking more than the upper limit, and see our guide to supplement and med interactions.
Which Form Fits Your Stack
Rala, the AI behind Reverse Age Lab, adds up the vitamin D in everything you take, checks it against the upper limit and your meds, and builds one Daily Protocol with the form and dose that fit your goals. Get a protocol with the right form and dose for me.
Is this medical advice? No. This guide sets out the published research on vitamin D2 and D3; it is not a diagnosis, and Rala isn't a medical device or a clinician. Talk to your doctor before changing your vitamin D, especially if you take meds.
Frequently Asked Questions
Is vitamin D3 better than D2?
For raising blood vitamin D, yes: D3 raised it more than the same amount of D2 in a pooled analysis of trials and in a 12-week trial of 335 women. Both forms raise it.
Is vitamin D3 vegan?
Most D3 is made from lanolin in sheep's wool, so it is not. D3 made from lichen is vegan, and D2 has always been.
What is the difference between ergocalciferol and cholecalciferol?
Ergocalciferol is vitamin D2, from plants, yeast and mushrooms. Cholecalciferol is vitamin D3, made in the skin in sunlight and found in oily fish and eggs.
Should I take vitamin D with food?
Yes. In a study of 50 older adults, D3 taken with a meal that contained fat reached a 32% higher peak in the blood than with a fat-free meal.
Sources
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. PubMed.
Tripkovic L, Wilson LR, Hart K et al. Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial. American Journal of Clinical Nutrition, 2017. PubMed.
Ross AC, Manson JE, Abrams SA et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. Journal of Clinical Endocrinology and Metabolism, 2011. PubMed.
Dawson-Hughes B, Harris SS, Lichtenstein AH et al. Dietary fat increases vitamin D-3 absorption. Journal of the Academy of Nutrition and Dietetics, 2015. PubMed.
