Is Riboflavin (E101) Vegan?

Vegan status: Depends on Source

E-number: E101

Also known as: Vitamin B2, Lactoflavin, Riboflavin-5'-phosphate (E101a)

Source

Can be derived from: (1) fermentation using bacteria or yeast [vegan], (2) animal sources such as whey or egg white [not vegan]. The vast majority of commercial riboflavin used in food and supplements is now produced via fermentation (primarily using Ashbya gossypii, a fungus).

Commonly found in

Fortified plant milks, breakfast cereals, energy drinks, bread, multivitamins, baby formula, some yellow-coloured foods.

Vegan alternative: Fermentation-derived riboflavin is the vegan form and is the industry standard. Contact the manufacturer if sourcing is unclear.

Notes

E101 is widely considered vegan in practice because fermentation-derived riboflavin dominates the market. Two main production organisms are used: the fungus Ashbya gossypii (Eremothecium gossypii) and the bacterium Bacillus subtilis. The animal-derived form (from whey) is commercially obsolete. In supplements, it is worth confirming the manufacturing method if you want absolute certainty.