E101I - Riboflavin

At a glance

• What it is: Riboflavin, also called vitamin B2; E-number E101i.
• What it does: Gives foods a yellow hue and can fortify them with vitamin B2.
• Where it’s used: Drinks, breakfast cereals, confectionery, baked goods, dairy and dairy alternatives, sauces, and soups.
• How it’s made: Mostly by microbial fermentation, then purified to food-grade crystals.
• Safety: Approved by U.S. and EU regulators for use in foods; no numerical acceptable daily intake (ADI) was set by EFSA due to low toxicity.

Why is Riboflavin added to food?

Food makers use riboflavin mainly as a color additive to provide a natural-looking yellow to yellow‑orange shade. In some products it also serves as a nutrient fortifier, helping maintain vitamin B2 levels after processing or storage losses.¹ Color additives in the U.S. are regulated, and riboflavin is listed as “exempt from certification,” meaning it doesn’t require batch-by-batch dye certification before use.¹

There are two related additives in this family: riboflavin (E101i) and riboflavin‑5′‑phosphate (E101ii). The phosphate form is often chosen when formulators need a more readily water‑dispersible option.

What foods contain Riboflavin?

You can find E101i in many everyday items:

• Soft drinks, sports drinks, and flavored waters
• Breakfast cereals and cereal bars
• Baked goods, cake mixes, fillings, and frostings
• Dairy products and dairy alternatives (yogurts, milk drinks)
• Savory snacks, soups, sauces, and dressings
• Confectionery and chewing gum

On labels, look for “riboflavin,” “vitamin B2,” “E101,” or “E101i.”

What can replace Riboflavin?

Depending on the shade, formulators might use:

• Plant colors: curcumin (golden yellow), annatto (yellow to orange), lutein (yellow), paprika extract (orange‑red)
• Carotenoids: beta‑carotene, carotenoids
• Caramels: caramel for brownish yellow
• Synthetic dyes: tartrazine or sunset yellow FCF where allowed

The best substitute depends on pH, light exposure, desired shade, and labeling goals (for example, “from natural sources”).

How is Riboflavin made?

Most food‑grade riboflavin is produced by controlled fermentation using microorganisms such as Ashbya gossypii or Bacillus subtilis. After fermentation, the broth is filtered, and riboflavin is crystallized, washed, and dried to meet purity specifications.² Older chemical synthesis routes exist but are less common today due to the efficiency of modern fermentation processes.²

Is Riboflavin safe to eat?

Regulators in the U.S. and EU allow riboflavin for coloring foods under good manufacturing practice. In the U.S., it is a color additive exempt from certification and may be used in foods, ingested drugs, and cosmetics within these limits.¹ The European Food Safety Authority (EFSA) re‑evaluated riboflavins (E 101) and did not set a numerical acceptable daily intake (ADI), concluding there was no safety concern at reported use levels.²

Riboflavin is a water‑soluble vitamin. Extra amounts are excreted in urine, which can appear bright yellow—this harmless effect is well known when intake is high.³

Does Riboflavin have any benefits?

Yes. Riboflavin is vitamin B2, a nutrient your body needs to help release energy from carbohydrates, fats, and proteins. It works as part of coenzymes called FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide), which support energy metabolism and many oxidation‑reduction reactions in cells.³ Typical recommended intakes are met through a balanced diet; deficiency can lead to symptoms such as sore throat, mouth or lip cracks, and a swollen tongue.³

Who should avoid Riboflavin?

• Most people do not need to avoid riboflavin in foods.
• If your clinician has advised you to limit specific vitamins or supplements, follow that advice.
• Very high supplemental intakes can turn urine bright yellow; this is expected and harmless for most people, but check with a healthcare professional if you have concerns.

Myths & facts

• Myth: Riboflavin is an “artificial dye.” Fact: It is vitamin B2 and occurs naturally; the food‑grade ingredient is typically made by fermentation.
• Myth: Because it glows under UV light, it’s radioactive. Fact: Riboflavin is fluorescent, not radioactive.
• Myth: It always comes from animal sources. Fact: Commercial riboflavin for foods is commonly produced by microbial fermentation.

Riboflavin in branded foods

How it appears on pack:

• Ingredient lists: “Riboflavin,” “Vitamin B2,” “E101,” or “E101i”
• Sometimes listed under “Color(s)” or “Colour(s)”

Common product categories:

• Ready‑to‑drink beverages and mixes
• Breakfast cereals and fortified grain products
• Baked goods, fillings, and icings
• Yogurts and dairy‑alternative drinks
• Confectionery and gums

Tip: If you want to avoid added colors, scan the ingredient list for “Color” and check for riboflavin or other color names.

References

Footnotes

1. Color additives exempt from certification; Riboflavin — U.S. FDA (21 CFR 73.450). https://www.ecfr.gov/current/title-21/section-73.450 ↩ ↩² ↩³

2. Scientific Opinion on the re‑evaluation of riboflavins (E 101) as food additives — EFSA. https://www.efsa.europa.eu/en/efsajournal/pub/3357 ↩ ↩² ↩³

3. Riboflavin Fact Sheet for Health Professionals — NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Riboflavin-HealthProfessional/ ↩ ↩² ↩³