E101 – Riboflavin (Vitamin B2) (i, ii)

Safety grading GREEN – SAFE

E101 (riboflavins) is graded GREEN – SAFE. It is a vitamin-derived food colour with a long history of dietary exposure and a strong safety record at the levels used to colour foods.

In the EU, riboflavin (E101(i)) and riboflavin-5′-phosphate sodium (E101(ii)) are authorised food colours and are listed in the EU Food and Feed Information Portal. EFSA has re-evaluated them as food additives and concluded they are unlikely to pose a safety concern at current reported uses and exposure levels. Internationally, JECFA (Joint FAO/WHO Expert Committee on Food Additives) has a group ADI (Acceptable Daily Intake) “not specified” for riboflavin and related riboflavin sources. This means a numerical ADI is not considered necessary when used as intended. In the United States, riboflavin is permitted as a colour additive under GMP (Good Manufacturing Practice) and is listed as exempt from certification. It is also recognised as GRAS (Generally Recognized as Safe) for certain direct-food uses.

Riboflavin is an essential nutrient involved in energy metabolism. In the body it is converted into FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide), cofactors needed for many enzymes. Human experience with riboflavin from food is extensive, and toxicology data consistently show very low systemic toxicity. Peer-reviewed reviews describe that oral intake from the diet and typical supplements rarely causes clinically meaningful side effects, because absorption is regulated and excess riboflavin is excreted, often causing harmless bright-yellow urine.

Credible risk signals at realistic exposure are minimal. At very high supplemental doses, some people report mild gastrointestinal discomfort. Bright yellow urine is common at higher intake and is harmless. True allergy to riboflavin preparations is uncommon. These effects do not indicate meaningful systemic risk at food additive levels, so a GREEN grade is appropriate.

If you use high-dose supplements for medical reasons, follow medical advice. For typical food use as E101, riboflavins are considered safe for the general population, including children.

Should You Avoid E101?

Most consumers do not need to avoid E101. If you prefer to minimise additives, you can choose products coloured with whole-food ingredients, but from a safety standpoint riboflavin-based colouring is among the lowest-concern options. If you have a rare, confirmed sensitivity to riboflavin preparations, avoid products listing E101, riboflavins, riboflavin, or riboflavin-5′-phosphate.

Common Uses

Processed cheese and cheese spreads – to enhance a yellow colour
Confectionery and desserts – to provide a stable yellow hue
Bakery mixes, icings, and fillings – for consistent colouring
Breakfast cereals and snack coatings – visual standardisation between batches
Instant soups, sauces, and seasonings – colour correction and product identity
Some beverages and drink powders – yellow tint, depending on formulation

Common names / Synonyms

Riboflavin
Riboflavins
Vitamin B2
Lactoflavin
Riboflavin-5′-phosphate (often the sodium salt)
INS 101
E101(i) (riboflavin) and E101(ii) (riboflavin-5′-phosphate sodium)

What is it?

E101 refers to riboflavins, a group that includes riboflavin itself and a more water-soluble derivative, riboflavin-5′-phosphate sodium. Riboflavin is a naturally occurring yellow pigment found in many foods, including milk, eggs, leafy vegetables, and whole grains. It also functions as an essential vitamin. Chemically, riboflavin contains an isoalloxazine ring system that absorbs blue light, which gives it its characteristic bright yellow colour. This pigment property is why it works well as a food colouring, even at low concentrations.

In manufacturing, food-grade riboflavin is commonly produced by controlled fermentation using microorganisms, followed by purification to meet specifications. Industrial fermentation routes often use strains of Bacillus subtilis or Ashbya gossypii, because they can produce riboflavin efficiently at scale. Historically, chemical synthesis was used more often, but fermentation production is widely used in modern supply chains for both cost and consistency. The phosphate form (E101(ii)) is used when better solubility is needed in water-based products. In the intestine it is readily converted back to riboflavin by enzymes, so it ultimately serves as the same vitamin compound in the body.

Technologically, E101 is added to restore or enhance yellow colour, helping products look consistent after processing or storage. Riboflavin is relatively stable to heat in many dry foods, but it is sensitive to light, which can break it down. That is why some riboflavin-coloured products are packaged to reduce light exposure. Formulators also pay attention to pH and processing conditions, because colour intensity and stability can vary between products.

Because riboflavin is an essential nutrient rather than a reactive preservative, it is not used to inhibit microbes. Its main role is visual colouring. In practice, manufacturers choose between E101(i) and E101(ii) based on the product matrix: the phosphate form can be easier to disperse in liquids, while standard riboflavin is often suitable for dry mixes and coatings.

Where it’s allowed (EU vs US)

E101 is authorised in the EU as a food colour (riboflavins). In the US, riboflavin is permitted as a colour additive for foods under GMP (Good Manufacturing Practice) and is listed as exempt from certification. It also appears in US regulations as GRAS (Generally Recognized as Safe) for certain direct-food uses, reflecting its long-standing acceptance as a vitamin ingredient.