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E101ColorantLow concern
Riboflavin
In plain words
The short version
Vitamin B2 — used both as a yellow-orange colorant and as a nutritional fortifier.
Why it's green
It's widely considered safe at the amounts used in food, so we mark it green. The Safety section below has the details.
Safety profile
No ADI required — essential nutrient. Excess is excreted in urine, producing the characteristic bright yellow color. Considered safe at any food-relevant level.
The detail
Isolated from milk whey in the 1920s; structure elucidated by Richard Kuhn (Nobel Prize 1938) and Paul Karrer. Commercial production today is mostly by fermentation of microorganisms (Bacillus subtilis, Ashbya gossypii) on plant-derived substrates.
Used to color sauces, cereals, dairy desserts, and ice cream a soft yellow-orange. Also added to fortified flours and supplements to meet nutritional B2 needs. Riboflavin-5'-phosphate (E101(ii)) is more water-soluble and is used in clear beverages.
Yellow-orange crystalline powder, sparingly soluble in water (the phosphate form is more soluble). Fluorescent under UV. Sensitive to light — can degrade quickly in clear-glass packaging.
Permitted globally without restrictive limits for food use.
Sources
- WHO JECFA database — Riboflavin (evaluation 2021, 92nd meeting, TRS 1037) — Joint FAO/WHO Expert Committee on Food Additives (JECFA), 2021. No numerical ADI (group ADI 'not specified')
- EFSA — Scientific Opinion on the re-evaluation of riboflavin (E 101(i)) and riboflavin-5'-phosphate sodium (E 101(ii)) as food additives (EFSA Journal 2013;11(10):3357) — European Food Safety Authority (EFSA ANS Panel), 2013. No ADI allocated; no safety concern at authorised uses
- 21 CFR 73.450 — Riboflavin (color additive exempt from certification; CFR 2025 edition) — U.S. FDA / Code of Federal Regulations (govinfo.gov, 2025 edition), 2025. US colorant use in foods generally at GMP
- 21 CFR 184.1695 — Riboflavin (affirmed GRAS; CFR 2025 edition) — U.S. FDA / Code of Federal Regulations (govinfo.gov, 2025 edition), 2025. US GRAS as nutrient, no limit other than GMP
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.