What is Riboflavin?

Riboflavin is a nutrient necessary for maintaining good health in humans and animals. It is also commonly refered to as vitamin B2.

As a food additive, it is used as an deep yellow – orange – red food colouring. Note that “flavin” comes from the Latin word for yellow, “flavus”.


Riboflavin is a water soluble vitamin produced by plants and many micro-organisms. Humans cannot produce riboflavin even though it is essential to life. Insufficient riboflavin (called Ariboflavinosis) can result in loss of hair, inflammation of the skin, vision deterioration, and growth failure.

Industrially, it can be produced by a variety of bio-technologies using fungus or bacteria. Some types of bacteria (Bacillus subtilis) have actually been genetically modified to increase their riboflavin production.1

Common Uses:

Riboflavin can be difficult to incorporate into most foods due to poor solubility and because it degrades quickly when exposed to sunlight.

When used to fortify foods, typical products include cereals, sauces, vitamin supplements, soups.

As a food colouring, it is commonly found in candy.


Health Issues / Side Effects:

We need riboflavin to survive, so it is probably quite safe as a food additive, especially in the small quantities required for food colouring.

In some people, riboflavin may cause urine to turn a darker yellow-orange colour. When consumed in high amounts, it may cause diarrhea and/or an increase in urine.2

E Number:

There are actually two types of riboflavin used as colouring agent. The E Numbers are 101 and 106.

Riboflavin 5′-phosphate has an E Number of 101a. ┬áIt is sometimes used because it is more soluble.

Riboflavin 5′-sodium phosphate has an E Number of 106.


I have not been able to find any product that lists riboflavin as an ingredient specifically added to provide colour. It is hard, because Canada does not require product labels to specifically state what kind of food colouring is used.
If anybody knows of such a product (in any country) please leave a comment.


  1. IPCS – International Programme on Chemical Safety
  2. WebMD – Riboflavin


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26 Comments on “What is Riboflavin?

  1. Interesting, I had no idea riboflavin was used as a food coloring. And I’d never made the mental connection between bioflavonoids and riboflavin. But of course that makes perfect sense– they are both yellow.

  2. Theres 1.7mg of Riboflavin in Monster (energy drinks), and probably more or less amounts in other energy drinks as well.

    • Thanks Tasia.
      I’ve never actually tasted one of those energy drinks. Do you think the riboflavin is added for colour, or for vitamin enrichment?

  3. Hello ..
    I found a riboflavin as an ingredient in a fried noodles called Indomie ..
    I am from saudi arabia

    • Lately, I ve been eating lots of Indomie noodles only to notice that its making my pee neon green/bright yellow. Reading your comment now gives It sense. I’m in Lagos, Nigeria

  4. I’ve found riboflavin added in Smedley’s mushy peas along with another food colouring (Brilliant blue FCF). Presumably this is added specifically for it’s food colouring properties in order to make the strong green colour of mushy peas.

  5. Ribovlavin is listed as an ingredient in Westminister Bakers Co. Saltines made in Rutland, VT in the U.S.

  6. Riboflavin is added to certain makes of Piccalilli – certainly in the UK. My grandmother used to call piccalilli ‘mustard pickle’ as it is made with mustard to give it the sharpness. I assume the mustard is not yellow enough!!

  7. I am a Nigerian and i have been able to found dat riboflavin (E101) is used in ‘the indomitables pack chicken flavour (u like no other special pack) and i was bordered and eager to know why is it that each time i eat it my urine turns dark yellow? But wit ur post, am relief. Thanks alot

  8. Edmonds Custard powder (New Zealand) ingredients list is ‘Maize Cornflour, Colours (Beta-carotene, Riboflavin), Salt, Flavour’

  9. Riboflavin is specifically listed as a colouring agent in 1000mg vitamin c fizzy tablets in the UK.

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