My diet:

E101 Riboflavin (Vitamin B2)

E101ColorsOrigin: Fermented
Get a personal answer

Pick your family’s diets in the bar above.

Every diet

VeganYes
Gluten-freeYes
HalalYes
KosherYes
KetoYes
Low-FODMAPYes
The short answer
Riboflavin (E101) is vitamin B2, and it happens to be bright yellow. Used as a color or a nutrient, it is one of the safest additives on a label.
Generally safe

Fine for most people at normal amounts.

E-numberE101
Comes fromFermented
What it doesColors
Glycemic index—
Daily limitNot set
Also calledRiboflavin, Vitamin B2

Rules by country

🇺🇸 US FDAApproved
🇪🇺 European UnionApproved
🇨🇦 Health CanadaApproved
CaliforniaNo extra rules

Riboflavin is an approved yellow color and a vitamin in the US, the EU and Canada. Regulators have not set a numerical daily limit for its use as a color, because excess is excreted.

Daily limit: Experts haven’t set a number because normal food amounts are far below any level of concern.

What is it?

Riboflavin gives custards, cereals and vitamin drinks a yellow cast and replaces a vitamin that milling can strip out of grain. The phosphate form (E101a) dissolves more easily in watery foods.

Where it comes from: Almost all food riboflavin is made by fermenting sugars with microbes such as Ashbya gossypii, then purifying the yellow vitamin.

Why it’s in food

  • Yellows custards and sauces
  • Fortifies cereals
  • Colors vitamin drinks
  • Replaces lost B2

Often found in

Breakfast cerealBaby foodVitamin drinksCustardProcessed cheeseMeal replacements

Also listed as: Riboflavin, Vitamin B2, Lactoflavin, Riboflavin-5-phosphate, E101a

Health & gut impact

Vitamin roleBenefit

Riboflavin is an essential vitamin. The body uses it in energy metabolism and spills the extra into urine, which can turn bright yellow.

NIH Office of Dietary Supplements, Riboflavin

Color useConcern

As a food color, riboflavin is considered safe. Its drawback is practical: the yellow fades in strong light.

EFSA re-evaluation of riboflavin (2013)

What can I use instead?

Curcumin

Ratio: To shade

Best for: A stronger yellow

Egg yolk

Ratio: One yolk

Best for: Custards, not vegan

Related

More colors:

Allura Red AC (Red 40) E129Red 40 (E129) is a petroleum-based dye. It's legal in the US and EU, but European packages must carry a warning about hyperactivity in children, and California is removing it from school food.Best to avoidAmaranth dye E123Amaranth dye (E123) is a synthetic red that the US banned in 1976. Europe still allows tiny uses. It is not the amaranth seed sold as a gluten-free grain.Best to avoidAmmonia caramel (Caramel III) E150cAmmonia caramel (E150c) is the caramel class made with ammonia and no sulfite, common in beer. It is approved, but like cola caramel it can contain 4-MEI, which California lists under Proposition 65.Use in moderationAnnatto E160bAnnatto (E160b) is a natural orange color from achiote seeds. It's what makes cheddar orange. It's safe and vegan, though it's one of the few natural colors that can trigger allergies.Generally safe

Common questions

Why does vitamin B2 turn urine yellow?

Kidneys excrete riboflavin they do not need. The vitamin itself is yellow, so the urine is too. That is expected, not a sign of harm.

Is Vitamin B2 safe?

Generally safe (96/100). Riboflavin is an approved yellow color and a vitamin in the US, the EU and Canada. Regulators have not set a numerical daily limit for its use as a color, because excess is excreted.

Spotted a mistake on this page? Report it ›

Scientific sources & regulatory citations
  • 21 CFR 184.1695 (US FDA)
  • EFSA OpenFoodTox: E101
  • NIH Office of Dietary Supplements, Riboflavin
  • EFSA re-evaluation of riboflavin (2013)

INS 101 · CAS 83-88-5