Vitamin forms and labels
A label can name a vitamin, a chemical form, a unit, or a percentage of a reference intake. Those pieces answer different questions. Reading them together prevents a familiar name—such as vitamin A or vitamin E—from being mistaken for one universal measurement.
One vitamin, several forms
Vitamin A includes preformed retinoids such as retinol and provitamin A carotenoids such as beta-carotene. NIH expresses vitamin A reference values as retinol activity equivalents (RAE) because these compounds do not have identical activity. Vitamin E also names a family of tocopherols and tocotrienols, while vitamin K includes phylloquinone and menaquinones.
That is why the small print may matter. Retinol, beta-carotene and alpha-tocopherol name particular compounds, while a parent vitamin name can cover a broader family.
Units carry meaning
Vitamin A may appear in micrograms RAE, and older material may use International Units. NIH explains that an IU-to-RAE conversion depends on whether the source is retinol, supplemental beta-carotene, or dietary beta-carotene. A conversion is therefore only defensible when the source form is known.
Vitamin D is commonly reported in micrograms or International Units, and vitamin E may be shown in milligrams. Always read the unit with the number; matching numbers in different units do not mean matching amounts.
Per 100 g and reference intake
EU food-information rules use per 100 g or per 100 ml as the standard basis for a nutrition declaration, with portion information allowed in addition when the portion is defined. The same regulation lists adult nutrient reference values for vitamins and minerals and permits percentages of those values when a vitamin or mineral is declared.
A percentage shows how the stated amount compares with a label reference. It is not a personal requirement. Read it alongside the serving: a glass may contain more than the 100 ml used in the main declaration.
References
Source-checked educational draft. Human editorial review pending.
NIH Office of Dietary SupplementsVitamin A and Carotenoids: Fact Sheet for Health ProfessionalsSource accessed 2026-09-05NIH Office of Dietary SupplementsVitamin D: Fact Sheet for Health ProfessionalsSource accessed 2026-09-05NIH Office of Dietary SupplementsVitamin E: Fact Sheet for Health ProfessionalsSource accessed 2026-09-05NIH Office of Dietary SupplementsVitamin K: Fact Sheet for Health ProfessionalsSource accessed 2026-09-05EUR-LexRegulation (EU) No 1169/2011 on food information to consumersSource accessed 2026-09-04European CommissionNutrition labellingSource accessed 2026-09-04