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E101aColorantLow concern
Riboflavin-5'-Phosphate
In plain words
The short version
The phosphate ester of vitamin B2 — a more water-soluble form for fortification and yellow coloring.
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
ADI not specified — considered safe. Hydrolyzed in digestion to riboflavin and phosphate, both essential nutrients. Excess water-soluble vitamins are excreted in urine (sometimes producing the bright-yellow urine color associated with B-complex supplements).
The detail
Manufactured by chemical phosphorylation of riboflavin (E101) followed by neutralization. The phosphate group dramatically improves water solubility (~80× plain riboflavin), making it the preferred form for clear and lightly colored beverages.
Used as a yellow-orange colorant and B2 vitamin source in fortified beverages, yogurts, dietary supplements, and egg-substitute products. Provides natural yellow tones without the cloudiness or sedimentation of plain riboflavin.
Yellow-orange crystalline powder. Highly soluble in water (much more than plain riboflavin). Sensitive to light — degrades in transparent packaging.
Permitted globally without restrictive limits.
Sources
- WHO JECFA database — Riboflavin 5'-phosphate sodium (INS 101(ii)) — WHO / FAO Joint Expert Committee on Food Additives, 2021. Safety: group ADI 'not specified' (2021), replacing the earlier 0–0.5 mg/kg bw
- US eCFR — 21 CFR 184.1697 Riboflavin-5'-phosphate (sodium) — U.S. eCFR (Office of the Federal Register), 2026. Regulation: US GRAS affirmation as a nutrient supplement (milk products, infant formula)
- Commission Regulation (EU) No 1129/2011 establishing the Union list of food additives — Publications Office of the EU (Official Journal L 295), 2011. Regulation: E 101 riboflavins are EU food colours authorised at quantum satis (Group II)
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.