Vitamin D2 vs vitamin D3

At a glance

Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) are both permitted forms of vitamin D in EU food supplements. The vitamin D2 vs D3 choice is therefore about sourcing, positioning and processing. Because labels declare vitamin D by mass, a given label claim needs the same mass of either pure substance. The forms differ in molar mass, starting material and the documentation each source carries. This page compares the materials only, not their behaviour in the body.

Content per gram and label-claim arithmetic

EU labels declare vitamin D in micrograms, so a 10 µg claim needs 10 µg of vitamin D whichever form you use. The molar masses, 396.6 g/mol for D2 and 384.6 g/mol for D3, do not enter the label calculation. They matter when you compare amounts of substance, for example in analytical work.

The D2 molecule is about 3.1 % heavier (396.6 ÷ 384.6 = 1.031). A given mass of D2 therefore holds about 3 % fewer molecules than the same mass of D3.

In production you weigh a diluted preparation, not crystals. The calculation is: mass of preparation (mg) = label claim (µg) × 1,000 ÷ declared content (µg per g). The declared content comes from the certificate of analysis for the lot. Add any overage your stability data justify; the overage calculator does this step. If a customer specification is written in international units, convert it with the vitamin unit converter before you calculate.

Ask for the form and declared content you need in the quote form. SoleChem sends the specification sheet and certificate of analysis with its quote.

Solubility, taste and processing

Both forms are practically insoluble in water and dissolve in oils and fats. Both are sensitive to light, oxygen and heat. Acidic conditions also promote isomerisation, so neither form tolerates an unprotected acidic matrix well.

For these reasons both are supplied as oily solutions with an antioxidant, or as encapsulated dry powders and beadlets. Oily solutions suit softgels and drops. Dry forms suit tablets, capsules and powder blends.

The carrier system decides much of the processing behaviour. Beadlets may use gelatin, gum acacia or modified starch. The carrier affects compression, vegetarian positioning and allergen review, so check it on the specification sheet.

Microgram claims make content uniformity the main manufacturing risk. Blend the diluted preparation in stages and validate mixing for each batch size. Gummies combine heat during cooking with an acidic matrix. Choose a preparation intended for that process and confirm stability in the finished product.

At microgram levels taste is rarely a deciding factor. The carrier and antioxidant system matter more than the vitamer.

EU regulatory status

Annex I of Directive 2002/46/EC lists vitamin D among the vitamins allowed in food supplements, with the microgram as its unit. Annex II lists both cholecalciferol and ergocalciferol as permitted forms. The guide to permitted vitamin and mineral forms explains how the annexes work.

Maximum amounts per daily portion are not harmonised at EU level. Member states set them nationally, and they differ; see maximum levels by EU country. The labelling guide covers how the amount and the form are declared.

UV-treated mushroom powders and UV-treated yeast are separate entries in the Union list of novel foods. They are not the purified substances discussed here. If a supplier offers D3 from a non-conventional source, check its status under Regulation (EU) 2015/2283; the novel food guide explains how.

For claim wording, use the EU Register of nutrition and health claims and the health-claims guide.

Choosing between them

• Source and positioning. D2 starts from ergosterol of yeast or fungal origin. Conventional D3 starts from lanolin. If a product is positioned as plant-based, the source and the carrier both need documented support.
• Customer specifications. Retailer and brand specifications often name the vitamer. Match the specification rather than substituting one form for the other.
• Format and carrier. Pick the supplied form first (oil, powder, beadlet), then the vitamer. The carrier drives processing more than the choice of D2 or D3.
• Analytics. Chromatographic methods separate the two forms. Make sure your laboratory’s method is set up for the form you use.
• Stability. Both degrade under similar conditions. Base overage on stability data in your own matrix, not on the vitamer alone.

Combining both forms in one product is uncommon. It adds a second stability profile and requires the method to quantify both forms and report their sum as vitamin D. Keeping one form per product, and choosing the form per product range, is simpler to specify and test.