Vitamin D2
Compiled from published pharmacological and botanical literature. Not independently verified by Herbuno. Spotted an error or have a correction? Flag it below →
| Compound Class | Secosteroid; fat-soluble vitamin (ergocalciferol) |
| Molecular Formula / CAS | C28H44O · CAS 50-14-6 |
| Source | Shiitake (Lentinula edodes) — UV irradiation converts fungal ergosterol to ergocalciferol |
| Standardisation | >8,000 IU/g ergocalciferol by HPLC |
| Comparator Forms | Vitamin D3 (cholecalciferol) from lanolin or lichen; synthetic D2 from yeast ergosterol |
| Solubility / Format | Fat-soluble; supplied as mushroom powder concentrate for capsules, tablets and dry blends |
| Regulatory Note | Established NRV and authorised EU health claims for vitamin D; vegan-suitable |
| Buy from Herbuno | Shiitake >8,000 IU/g |
| Origin | Processed / Sourced from India |
| MOQ | R&D 100 g / 250 g (subject to stock) · Pilot batch 1–5 kg · Bulk 10 kg, 25 kg and above |
| Lead Time | Dispatch within 72 hrs from stock · fresh-batch production (typically 50 kg+): 10 working days |
| Documentation | CoA & MSDS standard with every lot |
Name origin: Ergocalciferol takes its name from ergosterol, its precursor, which was itself named for ergot, the fungus from which it was first isolated in the 1880s. The D2 designation reflects that it was the second vitamin D form characterised, in the early 1930s, and it was the original commercial vitamin D — irradiated ergosterol was the basis of the first mass anti-rachitic fortification programmes before D3 displaced it.
Traditional use: Shiitake carries one of the longest documented records of any cultivated fungus, with deliberate cultivation on logs recorded in China from around the twelfth century and a continuous place in Chinese and Japanese food and medicine since. Traditionally valued as a tonic food rather than for any vitamin content, its relevance here is more specific: sun-drying, a traditional preservation method, incidentally generates vitamin D2 from the ergosterol in the fungal cell membrane. The modern UV process is a controlled version of something the tradition did accidentally.
Research trajectory: Vitamin D2's research history divides into two phases. Through the mid-twentieth century it was simply vitamin D for fortification purposes. It was then progressively displaced by D3 as evidence accumulated that D3 raises serum 25(OH)D more effectively. The recent phase is driven by plant-based formulation demand, where the practical question became whether UV-treated mushrooms deliver usable vitamin D at all — which, unusually for a food-source claim, has been tested directly in randomised trials.
Commercial source: Vitamin D2 is produced either by UV irradiation of yeast-derived ergosterol followed by purification, or by UV treatment of mushroom biomass which is then dried and standardised. The latter yields a food-source material where the vitamin sits within the mushroom matrix. Both are vegan-suitable; the mushroom route additionally supports a whole-food label position that isolated ergocalciferol cannot.
Evidence for Vitamin D2 Applications
The photochemistry is well defined: UV-B radiation cleaves the B ring of ergosterol between carbons 9 and 10 to give pre-vitamin D2, which then rearranges thermally to ergocalciferol. Mushrooms are unusually suited to this because ergosterol is the dominant sterol of the fungal cell membrane, so the precursor is abundant. This is a genuine conversion in the material rather than an addition, and it is the basis of the food-source claim. Claim strength: High.
The critical question — whether vitamin D2 in a mushroom matrix is actually absorbed — has been tested directly rather than assumed. In a five-week single-blinded randomised placebo-controlled trial, 26 subjects with serum 25(OH)D at or below 50 nmol/l received 28,000 IU of vitamin D2 either via a soup made from UV-B-irradiated button mushrooms or via a D2 supplement, or placebo, during winter. Serum 25(OH)D was significantly higher in the mushroom group than placebo by two weeks, and rose similarly in the mushroom and supplement groups at 3.9 and 4.7 nmol/l per week respectively. The authors concluded that bioavailability from the enhanced mushrooms was effective in improving vitamin D status and not different from a supplement. [Urbain 2011] Claim strength: High.
Subsequent work extended this to other populations, including a randomised controlled trial in prediabetic, vitamin D-deficient adults consuming UV-enhanced mushrooms daily over sixteen weeks. [Calvo 2014] The consistent finding across this literature is that the vitamin D2 generated in mushroom tissue behaves like ingested D2 — the matrix does not impair it. That is a more useful result than it may sound, because food-matrix claims frequently fail exactly this test. Claim strength: Moderate.
The unavoidable qualification is the D2-versus-D3 comparison, and a supplier of D2 should state it rather than leave buyers to discover it. A systematic review and meta-analysis of randomised controlled trials directly comparing the two concluded that D3 is more efficacious than D2 at raising serum 25(OH)D and suggested D3 as the preferred choice for supplementation. [Tripkovic 2012] Published correspondence on that paper notes the conclusion rested substantially on bolus dosing, with daily supplementation showing little difference — so for daily-dose products the gap is narrower than commonly asserted, but the direction of the evidence favours D3. Claim strength: High.
Which leaves a clear and honest positioning. D2 from shiitake is appropriate where a whole-food, mushroom-derived vitamin D is the design intent and where daily rather than bolus dosing is used. Where the objective is maximum efficiency in raising 25(OH)D per IU, particularly with intermittent high doses, D3 — including vegan D3 from lichen — is better supported. Both can be legitimately supplied; specifying which and why is the formulator's decision, and it should be made on this evidence rather than on source romance. Claim strength: High.
Sourcing mushroom vitamin D2: A UV-treated shiitake concentrate standardised above 8,000 IU/g is available from Herbuno, with CoA and MSDS on every lot. View Vitamin D2 >8,000 IU/g (Shiitake) →
Dosage & Formulator Specification
Production route. Shiitake biomass is exposed to controlled UV-B radiation, converting native ergosterol to ergocalciferol, then dried and standardised to a defined potency. The UV dose and its timing in the process materially affect yield; published work indicates that splitting the dose between sliced fresh material and the dried powder achieves higher conversion than a single exposure. Because the conversion depends on the ergosterol content of the starting biomass, cultivar and growing conditions influence achievable potency, which makes lot-specific assay the norm rather than a courtesy.
Analytical standardisation. Ergocalciferol is determined by HPLC with UV detection against a D2 reference standard, with potency expressed in IU per gram. Where the material is characterised fully, 25-hydroxyvitamin D2 may also be present, since fungal cytochrome P450 enzymes can hydroxylate vitamin D2 — but only when irradiation precedes drying, not the reverse. Specify whether your assay covers D2 alone or D2 plus 25(OH)D2, since the two give different numbers. Confirm the assay method on the purchase specification rather than accepting a bare IU figure.
Regulatory and handling context. Vitamin D has an established Nutrient Reference Value in the EU and authorised health claims including contribution to normal absorption of calcium and phosphorus, maintenance of normal bones and teeth, normal muscle function and normal immune system function. These claims attach to vitamin D and do not distinguish D2 from D3, so a D2 product carries the same claim eligibility at equivalent labelled IU — a point worth knowing given the efficacy difference discussed above. Tolerable upper intake levels apply to total vitamin D from all sources. Store cool, dark and dry; ergocalciferol is light- and oxygen-sensitive.
Formulation behaviour. At 8,000 IU/g, delivering a 400 IU dose requires 50 mg of material, which is a comfortable inclusion for capsules and tablets and considerably easier to handle than high-potency isolated vitamin D concentrates. As a mushroom powder the material carries colour and a distinct umami-savoury character that will read through in unflavoured or light systems, so it suits capsules, tablets and savoury or mushroom-forward formats better than clear beverages or delicate flavour systems. Retention studies indicate vitamin D2 in dried irradiated mushroom material is reasonably stable over extended storage, but generate matrix-specific data for label-claim purposes.
Frequently Asked Questions — Vitamin D2
Yes, and this has been tested directly rather than assumed. In a randomised placebo-controlled trial in adults with serum 25(OH)D at or below 50 nmol/l, vitamin D2 delivered via UV-B-irradiated mushrooms raised serum 25(OH)D significantly versus placebo and at a rate not different from a D2 supplement, at 3.9 versus 4.7 nmol/l per week. The mushroom matrix does not impair absorption.
It depends on the design intent, and we would rather set out the trade-off than sell past it. Meta-analysis of trials comparing the two found D3 more efficacious than D2 at raising serum 25(OH)D, and suggested D3 as the preferred supplementation choice. Published correspondence notes that conclusion rested largely on bolus dosing, with little difference for daily supplementation. D2 from shiitake suits whole-food positioning with daily dosing; D3, including vegan lichen D3, is better supported where efficiency per IU is the priority.
Yes. The authorised EU health claims are for vitamin D and do not distinguish between D2 and D3, so claim eligibility attaches to labelled vitamin D content rather than to form. This is worth knowing precisely because the forms are not equally efficacious at raising 25(OH)D, so regulatory equivalence and biological equivalence are not the same thing here. Claim wording and conditions of use remain your responsibility in your target market.
The ergosterol content of the starting biomass, which varies with cultivar and growing conditions, and the UV dose and its timing in the process. Published work indicates that splitting the UV dose between sliced fresh material and the dried powder gives higher conversion than a single exposure. Because of this variability, specify lot-specific assay rather than relying on a nominal potency figure.
It is worth clarifying, because it changes the number. Fungal cytochrome P450 enzymes can hydroxylate vitamin D2 to 25(OH)D2, but this occurs only when the material is irradiated before drying rather than after. Specify explicitly whether your assay covers ergocalciferol alone or ergocalciferol plus 25(OH)D2, so that you are comparing like with like across suppliers.
Every lot ships with a Certificate of Analysis and MSDS as standard. R&D quantities are available at 100 g and 250 g subject to stock, pilot batches at 1–5 kg, and bulk at 10 kg, 25 kg and above. Stock orders dispatch within 72 hours; fresh-batch production, typically 50 kg and above, runs to about 10 working days. Material is processed and sourced in India, giving procurement teams a documented alternative origin for vegan vitamin D supply.
Related compounds: Vitamin D3 · Vitamin K2-MK7 · Magnesium
Claim strength scale: High — consistent human data or established biochemistry. Moderate — supportive human data with limitations. Emerging — mechanistic or preliminary evidence only.