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Vitamin B2 (Riboflavin) — The Complete Supplement Guide

Energy-metabolism vitamin with a real, evidence-based use in migraine prevention. Function, deficiency, doses and safety.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsVitaminsB2 RiboflavinWater-soluble

Best known for the harmless bright-yellow tint it gives to urine — and, more usefully, for some of the better evidence among vitamins for preventing migraine. For the short dietary version, see the Vitamins page.

Read first. Riboflavin is very safe and excess is simply excreted (turning urine bright yellow — harmless). Migraine doses are high but well tolerated. Information, not a prescription.

Key takeaways

  • Among the better vitamin evidence for migraine prevention (~400 mg/day).
  • Everyday need ≈ 1.1–1.6 mg/day.
  • No upper limit set; the harmless bright-yellow urine it causes is normal.

Function

Riboflavin is the backbone of two key coenzymes (FAD, FMN):

  • Energy metabolism: FAD/FMN carry electrons in the reactions that release energy from carbs, fat and protein.
  • Activates other vitamins: needed to convert vitamin B6 and folate into their active forms.
  • Antioxidant support: helps regenerate glutathione, the body's master antioxidant.
  • Skin, eyes & mouth: maintains healthy skin and the linings of the eyes and mouth.

Different forms — and which to choose

RiboflavinStandard supplement form.
Riboflavin-5'-phosphate (FMN)The "active" form; marketed as better absorbed, difference is minor for most.

Absorption in the body

How muchAbsorbed in the upper gut with a limited capacity per dose; little stored, so regular intake matters. Food (especially with meals) aids uptake.

Deficiency symptoms

SymptomsCracked lips and mouth corners (cheilosis), a sore red tongue, skin and eye irritation, sometimes anaemia.
Who's at riskLow dairy/meat intake, vegans, pregnancy/lactation and heavy alcohol use.

Recommended intake

Adults ≈ 1.1–1.6 mg/day

Reference intakes:

  • Adults: ~1.1–1.3 mg ♀ / 1.3–1.6 mg ♂ per day

Best sources: dairy, eggs, lean meat, almonds and green vegetables.12

Therapeutic use

Migraine~400 mg/day has reasonable evidence for preventing migraine (takes 2–3 months to judge).
DeficiencyCorrecting deficiency and supporting B6/folate activation.

Therapeutic doses

Migraine: ~400 mg/day
EverydayDiet covers needs.
Migraine prevention400 mg/day, well tolerated; expect bright-yellow urine.

Toxicity & upper limit

No UL set
Upper limitNone established; poorly absorbed at high doses and readily excreted.1

Bottom line: riboflavin from dairy, eggs and greens covers everyday needs. Its stand-out supplement use is migraine prevention at ~400 mg/day — safe, cheap and worth a 2–3 month trial (harmless yellow urine aside).

← All supplementsShort dietary version

References

Reference and upper-limit values are general adult figures from official bodies; individual needs vary. Therapeutic doses describe clinical/research use, not prescriptions.

  1. US NIH Office of Dietary Supplements. Riboflavin — Health Professional Fact Sheet (function, forms, intakes, food sources, deficiency, therapeutic uses, upper limit, interactions). ods.od.nih.gov
  2. EFSA. Dietary Reference Values & Tolerable Upper Intake Levels for vitamins (European reference intakes and ULs). efsa.europa.eu

This article summarizes nutrition science from official health authorities and peer-reviewed sources for education. It is not a substitute for individual medical advice, and the doses given are not prescriptions — always consult a professional before therapeutic supplement use, in pregnancy, or alongside medication.

✓
Bodil Isaksson, Licensed Biomedical Scientist (Sweden)

At Food Health Lab we explain what the science says in plain language, and we cite our sources so you can check for yourself.

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