Vitamin D forms for supplement manufacturing

How the forms compare

For a manufacturer, the vitamin D2 vs D3 choice comes down to origin, product format and label positioning. It does not change how the amount is declared. Ergocalciferol (D2) and cholecalciferol (D3) are both declared in micrograms on EU labels, and for both forms 1 µg equals 40 IU. Structurally, D2 differs from D3 by an extra methyl group and an additional double bond in the side chain.

Crystalline vitamin D is rarely weighed into a batch as it is. Label claims sit in the microgram range, which is too small to dose and blend evenly. Manufacturers therefore buy a diluted form with a declared potency. Oil solutions suit softgels and drops, while dry powders and beadlets suit tablets, capsules, powders and effervescent formats.

Both forms are sensitive to light, oxygen, heat and acidic conditions. Diluted forms usually contain an antioxidant such as tocopherol, and dry forms shield the vitamin inside a carrier matrix. Stability in the finished product depends on matrix, moisture and packaging, so set overage from your own stability data.

The molar masses differ (396.6 g/mol for D2, 384.6 g/mol for D3), but labels declare mass, not moles. A declared 25 µg of either form is simply 25 µg of vitamin D. For a side-by-side view, see vitamin D2 vs vitamin D3.

Vitamin D IU to µg and label-claim arithmetic

The conversion is fixed and identical for D2 and D3: 1 µg = 40 IU, so 1 IU = 0.025 µg. Divide IU by 40 to get micrograms.

Diluted forms state their potency on the specification sheet, usually in IU per gram. The mass needed per serving is the label claim in IU divided by the potency in IU/g, before overage. To declare 25 µg (1,000 IU) per tablet from a powder of potency P IU/g, you need 1,000 ÷ P grams per tablet, plus overage.

Use the assayed potency on the certificate of analysis, not the nominal grade name. The vitamin unit converter and the overage calculator handle both steps. SoleChem sends the specification sheet and certificate of analysis with its quote; state the form and potency you need in the quote form.

Choosing a form

• Origin and positioning. D2 comes from fungal or yeast sources. D3 is traditionally made from lanolin, so a product positioned as vegan needs D2 or a D3 of documented non-animal origin. The specification sheet states the source.
• Format. Softgels and oil drops take an oil solution; see softgels. Tablets and hard capsules take a dry powder or beadlet; beadlets must tolerate the compression force used in tablets. Drink powders and effervescent tablets need a water-dispersible dry form. Gummies expose the vitamin to heat during cooking and depositing, so stability data matter most there.
• Content uniformity. Choose a dilution whose dosing mass is large enough to blend evenly at your serving size. Very potent dilutions in a small serving make uniformity harder to achieve.
• Combination products. D3 is often formulated with calcium or vitamin K. Check compatibility of the carrier with the other actives; see the calcium and vitamin K guides.
• Cost. Compare cost per microgram of vitamin D delivered, not per kilogram of powder, because potencies differ between diluted forms.
• Regulatory status. Both forms are permitted in EU food supplements; national maximum amounts still apply, as below.

EU regulatory status

Annex II of Directive 2002/46/EC lists both cholecalciferol and ergocalciferol as permitted forms of vitamin D in food supplements. Annex I lists vitamin D with µg as the unit, and Article 8 requires the declared amount in that unit. The permitted forms guide covers the Annexes in more detail.

General labelling follows Regulation (EU) No 1169/2011, whose Annex XIII sets a reference value for vitamin D in µg. Whether IU may appear next to µg is a matter of national practice; check it for each market. See labelling a food supplement in the EU.

Article 5 of the Directive provides for EU maximum amounts, but member states currently apply their own limits for vitamin D. These differ between countries, so a level accepted in one market may be refused in another. See maximum levels by EU country.

Adding vitamin D to ordinary foods falls under Regulation (EC) No 1925/2006, whose Annex II also lists both forms. Carriers and antioxidants in diluted forms must be permitted for that use under Regulation (EC) No 1333/2008, and Article 20 of Regulation (EU) No 1169/2011 decides whether they must appear in the ingredients list.

Vitamin D-containing ingredients such as UV-treated mushroom powder or UV-treated baker’s yeast are separate entries in the Union list of novel foods, with their own conditions of use. They are not covered here; see the novel food guide. Authorised claim wording is in the EU Register of nutrition and health claims; see the health claims guide.