Overview
ISO/TR 23304:2021 - Food products - Guidance on how to express vitamins and their vitamers content provides practical guidance for expressing vitamin quantities and the different molecular forms (vitamers) found in foods. It clarifies how to report vitamin mass, when to express vitamin activity, and how to interpret results from ISO and CEN analytical standards. The report is intended as a discussion basis between stakeholders and food control laboratories; it is informative rather than prescriptive or exhaustive.
Key technical topics and requirements
- Scope and purpose
- Guidance on how to express vitamin quantity, vitamers’ molecular forms in appropriate units, and, where relevant, vitamin activity.
- No normative references; intended to harmonize reporting and reduce misinterpretation.
- Definitions
- Clear definition of a vitamer: different chemical compounds of a vitamin with biological activity.
- Vitamin-specific guidance
- Detailed recommendations per vitamin (Vitamin E first, then other fat‑soluble and water‑soluble vitamins). Topics include expression units, conversion factors, and when activity equivalents should be used.
- Vitamin E complexity (illustrative example)
- Discusses differences between natural D‑alpha‑tocopherol and synthetic D,L‑alpha‑tocopherol, tocopherol esters and tocotrienols.
- Presents commonly used conversion factors and example calculations to convert measured mass into vitamin activity equivalents (e.g., mg alpha‑TE), and procedures when the molecular form is unknown.
- Describes two analytical approaches: saponification + HPLC (EN 12822) and direct extraction + HPLC (ISO 20633), and how method choice affects expression of results.
- Regulatory and regional considerations
- Reviews conversion factors and labelling units across regions and standards (EU, US FDA, CODEX, FSANZ, GB China), noting that labelling conventions differ internationally.
Practical applications and who uses this standard
- Food control laboratories - harmonize reporting of vitamin analyses, interpret analytical results in the context of regional labelling and fortification rules.
- Food manufacturers and formulators - convert ingredient/vitamer additions into label‑claim units and ensure compliance with fortification regulations.
- Regulators and enforcement bodies - assess lab results for conformity with national or regional rules.
- Nutrition scientists and database compilers - standardize nutrient composition databases by consistent expression of vitamers and vitamin activity.
- Quality assurance teams - reduce misinterpretation when analytical methods do not distinguish between stereoisomers or esters.
Related standards and guidance
- ISO and CEN analytical methods (e.g., EN 12822, ISO 20633) - used to generate quantitative data that ISO/TR 23304:2021 helps to interpret.
- Regional regulations and standards: EU regulations (e.g., Regulation (EU) No 609/2013, Regulation (EC) No 1925/2006, Directive 2002/46/EC), US FDA guidance, CODEX, FSANZ, and national standards (GB).
Keywords: ISO/TR 23304:2021, vitamins, vitamers, vitamin E, labelling, vitamin activity, alpha‑tocopherol, analytical standards, food fortification, ISO, CEN.
