Flavin mononucleotide
An orange-red food colour and biomolecule made from vitamin B2
No single value: Flavin mononucleotide is a material, and its colour varies. The background shows its family, orange.
Flavin mononucleotide is an orange-red compound made from riboflavin (vitamin B2). It acts as a food colouring (E101a) and is found in cells as a cofactor for enzymes and blue-light receptors. FMN is more soluble than riboflavin and is used in foods for children and in medical tests.
- Used as food colour E101a in Europe
- Made from riboflavin (vitamin B2)
- Naturally fluorescent with green emission
- Acts as a cofactor in enzymes
- Approved for medical use in the US in 2025
What colour is Flavin mononucleotide?
Flavin mononucleotide, often called FMN or riboflavin-5′-phosphate, is an orange-red compound. It is made from riboflavin, which is also known as vitamin B2. FMN is used as a food colouring and is found in many foods for babies, children, and in sweets and milk products. In the body, it acts as a helper molecule for enzymes and as a blue-light photo receptor.
Where does Flavin mononucleotide come from?
The name 'flavin mononucleotide' comes from its structure: it contains the flavin base, a ribitol sugar, and a phosphate group. It is produced in the body from riboflavin by the action of the enzyme riboflavin kinase. FMN is the main way riboflavin is found in cells and tissues, and is more soluble than riboflavin itself.
How is Flavin mononucleotide made?
FMN is made from riboflavin (vitamin B2) by adding a phosphate group, a process carried out by the enzyme riboflavin kinase. As a food additive, it is labelled E101a in Europe. A closely related dye, E106, is the sodium salt form and is quickly turned back into riboflavin in the body.
Where Flavin mononucleotide is used
FMN is used as a food colour in products for children, jams, milk products, and sweets. In medicine, it is used as a photoenhancer in corneal treatments and as a marker to assess organ transplant outcomes. Its natural fluorescence allows it to be measured in biological fluids without taking samples.
Orange around the world
What the orange family means from country to country.
Orange and black are the colours of Halloween, 31 October: orange for pumpkins and autumn leaves, black for night.
Festival and celebrationDanger and warningFearSource: HalloweenThe lowest band of the flag is orange, often called apricot, after the national fruit. The constitution says it stands for the creative talent and hard work of the people.
Politics and protestNature and renewalPrideSource: Flag of ArmeniaThe flag is split corner to corner. The orange half stands for the Buddhist tradition, and the white dragon across the middle for purity.
Sacred and holySource: Flag of BhutanOn 30 September people wear orange shirts to remember the children sent to residential schools. Phyllis Webstad's new orange shirt was taken from her on her first day at one.
Mourning and deathPolitics and protestGriefSource: National Day for Truth and ReconciliationOrange is also the colour of the New Democratic Party. Its sweep of Quebec seats in the 2011 election was called the Orange Wave.
Politics and protestSource: New Democratic PartyThe flag shows the island in copper orange on white. The colour recalls copper, which was mined here in ancient times and may have taken its name from Cyprus.
Politics and protestNature and renewalSource: Flag of CyprusShades and relatives of Flavin mononucleotide
A similar food dye is E106, which is the sodium salt of riboflavin-5′-phosphate. Both are related to riboflavin and are used in food. FMN can exist in oxidised, semiquinone, and reduced forms in the body, which are important in enzyme reactions.
Questions people ask about Flavin mononucleotide
What colour is flavin mononucleotide?
Flavin mononucleotide is orange-red and is used as a food colouring in many products.
Where does the name flavin mononucleotide come from?
The name comes from its structure: it contains a flavin base, a ribitol sugar, and a phosphate group.
What is FMN used for?
FMN is used as a food colour additive (E101a), as a cofactor in enzymes, and as a marker in medical tests.
How is FMN made?
FMN is made from riboflavin (vitamin B2) by adding a phosphate group through the action of riboflavin kinase.
Is FMN found in the body?
Yes, FMN is the main form of riboflavin in cells and acts as a helper molecule for many enzymes.
Good reading and sources
- Flavin mononucleotide on WikipediaEncyclopedia
- More pictures on Wikimedia CommonsPictures
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Flavin mononucleotide", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Rang rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. The swatch is an approximation: named colours are not fixed standards, and every screen shows them a little differently. If something is wrong, tell us. Last refreshed 2026-10-03.
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