Vitamin D2 Lowers Your D3: The Word to Check on the Label, and the 10 Vitamin D Supplements We Rank (All D3)
Vitamin D comes in two forms. A University of Surrey review pooled 11 randomized trials: people who took vitamin D2 ended them with about 18 nmol/L less vitamin D3 in their blood than control groups who took nothing, even as their total vitamin D went up. The word for D2 on a label is ergocalciferol. All 10 vitamin D supplements we rank are D3.
A sceptical woman lit in gold holds up two vitamin D softgels, one glowing and one dull, on pure black
Vitamin D comes in two forms, and a University of Surrey review found that taking one lowers your blood level of the other. If you are here from our video, the two answers it promised come first: the word to look for on your label, and the vitamin D supplements we rank.
Which word on the label means vitamin D2?
Ergocalciferol. The University of Surrey release on the review names it: "Vitamin D2, also called ergocalciferol, is commonly produced from fungi or yeast exposed to ultraviolet light." Vitamin D3 appears on a label as cholecalciferol. If a label only says "vitamin D", the form is in the Supplement Facts panel, usually in brackets after the amount.
What are the best vitamin D supplements?
We read the Supplement Facts panel of every product on our vitamin D ranking on October 16, 2026. All 10 declare cholecalciferol, vitamin D3. None is D2. Ranked by our score:
- #1 Thorne Vitamin D + K2 Liquid, 8.9: D3 with K2 in drops, contents NSF-certified
- #2 Pure Encapsulations Vitamin D3 5000 IU, 8.9: D3 in a vegetarian capsule, hypoallergenic
- #3 NOW Foods Vitamin D-3 5000 IU, 8.9: D3 from lanolin, the lowest cost per IU of the trusted brands
- #4 Sports Research Vitamin D3 5000 IU + K2, 8.9: vegan D3 from lichen, with K2 as MK-7
- #5 Life Extension Vitamin D3 with Sea-Iodine, 8.6
- #6 Doctor's Best Vitamin D3 5000 IU, 8.4
- #7 Nordic Naturals Vitamin D3 1000 IU, 8.1
- #8 Carlson Vitamin D3 Drops 2000 IU, 8.1
- #9 Nature Made Vitamin D3 2000 IU, 8.0
- #10 Bulk Supplements Vitamin D3 Powder, 7.6
The first four share the top score and differ in format: drops, a vegetarian capsule, a softgel, and a vegan softgel. The short list below is our number one, plus the vegan D3 for anyone who avoids animal sources.
Does vitamin D2 lower vitamin D3?
Yes, in blood levels. The review, published in Nutrition Reviews in 2025 by researchers at the University of Surrey, searched PubMed from 1975 to 2023, included 20 studies and pooled 11 randomized controlled trials. People who took vitamin D2 ended the trials with 17.99 nmol/L less 25-hydroxyvitamin D3 than control groups who took no supplement. Measured as the change over each trial, the difference was 9.25 nmol/L. Both results were statistically significant.
The authors suggest a regulating mechanism: when vitamin D rises, the body may clear 25-hydroxyvitamin D faster, D3 included. They also write that further research is needed before this changes clinical advice.
Does vitamin D2 still raise your total vitamin D?
Yes. The University of Surrey release says: "Vitamin D2 itself raises 25-hydroxyvitamin D2 and can contribute to total vitamin D status." A standard blood test reports total 25-hydroxyvitamin D, D2 and D3 together, so D2 can raise that number while D3 falls. An earlier meta-analysis from the same university, Tripkovic 2012 in the American Journal of Clinical Nutrition, found that D3 raised total 25-hydroxyvitamin D more than D2 when the two were compared head to head. Whether the drop in D3 matters for bones, immunity or anything else has not been studied; the review measured blood levels only.
Which vitamin D products are usually D2?
According to the University of Surrey, vitamin D2 is commonly produced from fungi or yeast exposed to ultraviolet light, so vitamin D made from mushrooms or yeast is usually D2. Read the label rather than assuming: vegan D3 made from lichen exists, and it is #4 on our ranking.
What about the 50,000 IU prescription capsule?
The 50,000 IU prescription vitamin D capsule in US pharmacies is ergocalciferol, vitamin D2: DailyMed, the National Library of Medicine's drug label database, lists it under that name. If your vitamin D is a prescription, do not stop or switch it on your own. Take this review to the doctor who prescribed it and ask whether D3 would suit you.
How do you check your own vitamin D?
- Find the Supplement Facts panel and read the form in brackets after vitamin D.
- Cholecalciferol is D3. Ergocalciferol is D2.
- For a vegan D3, look for lichen as the source.
- If the label gives no form at all, choose a product that does.
This is analysis of published research, not medical advice.
The 25-second version — as seen on TikTok, Reels & Shorts.
SOURCES
- Brown EIG, Darling AL, Robertson TM, Hart KH, Li J, Martin C, Warren MJ, Smith CP, Lanham-New SA, Elliott RM — "Effect of Vitamin D2 Supplementation on 25-Hydroxyvitamin D3 Status: A Systematic Review and Meta-Analysis of Randomized Controlled Trials", Nutr Rev 2025, doi 10.1093/nutrit/nuaf166. 20 studies reviewed, 11 meta-analysed; end-of-trial WMD −17.99 nmol/L 25(OH)D3 (95% CI −25.86 to −10.12), absolute change WMD −9.25 nmol/L (95% CI −14.40 to −4.10), against controls without supplementation (PMID 40973107)
- University of Surrey release, via ScienceDaily, October 2026. Verbatim: "Vitamin D2, also called ergocalciferol, is commonly produced from fungi or yeast exposed to ultraviolet light." and "Vitamin D2 itself raises 25-hydroxyvitamin D2 and can contribute to total vitamin D status."
- 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", Am J Clin Nutr 2012;95(6):1357-64. D3 raised total 25(OH)D more than D2 in head-to-head trials (PMID 22552031)
- DailyMed — Ergocalciferol capsule, Torrent Pharmaceuticals (prescription vitamin D2 capsule), label setid 4ae38744-020d-4c37-a6f1-88f55c2f1047