The animal is not killed to obtain it, which is the line a vegetarian diet draws. It remains an animal product, so it sits outside a vegan diet.
The two diets, side by side
A vegetarian diet excludes animals that were killed. A vegan diet excludes animal products entirely, whether the animal survived or not. Riboflavin sits in the gap between them: it clears the first bar and fails the second.
Riboflavin is vegan in practice. Nearly all commercial E101 is fermented by the fungus Ashbya gossypii or the bacterium Bacillus subtilis, and the whey-derived form has fallen out of commercial use. Fortified plant milk and cereal are safe bets; a supplement maker can confirm the method if you want certainty.
What it is
- Comes from
- 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).
- Which animal
- cow via whey, or hen via egg white
- Requires slaughter
- No, the animal keeps living
- Where you meet it
- Fortified plant milks, breakfast cereals, energy drinks, bread, multivitamins, baby formula, some yellow-colored foods.
- What replaces it
- Fermentation-derived riboflavin is the vegan form and is the industry standard. Contact the manufacturer if sourcing is unclear.
Editorial 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.
Frequently asked questions
Is Riboflavin vegetarian?
Vegetarian. The animal is not killed to obtain it, which is the line a vegetarian diet draws. It remains an animal product, so it sits outside a vegan diet.
Is Riboflavin vegan?
Depends on Source. Riboflavin is vegan in practice. Nearly all commercial E101 is fermented by the fungus Ashbya gossypii or the bacterium Bacillus subtilis, and the whey-derived form has fallen out of commercial use. Fortified plant milk and cereal are safe bets; a supplement maker can confirm the method if you want certainty.
Is riboflavin (E101) vegan?
In practice it is almost always vegan. The riboflavin used in food and supplements today is overwhelmingly produced by microbial fermentation on plant-based media. It can historically be derived from animal sources such as whey, but that route is considered commercially obsolete. Labels do not state the method, so contact the manufacturer if you need absolute certainty.
What is E101 made from?
E101 is made mainly by fermentation. Microorganisms are cultured in tanks and secrete riboflavin. The two main production organisms are the fungus Ashbya gossypii and the bacterium Bacillus subtilis. Chemical synthesis and animal-source extraction were used in the past but have largely been displaced.
Is vitamin B2 the same as riboflavin?
Yes, vitamin B2 and riboflavin are the same substance. On labels you may also see it as E101, lactoflavin, or riboflavin-5'-phosphate (E101a). The name used does not indicate whether it was made by fermentation or from an animal source.