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Moderate evidenceBrain & cognition

Vitamin B2 (Riboflavin)

High-dose riboflavin (400 mg/day) has reasonable evidence for reducing migraine frequency in adults, which is the one use worth considering. As a general supplement it does nothing for people who are not deficient, and deficiency is rare in developed countries.

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What the science says

  • Reduces migraine frequency in adults Moderate evidence

    Meta-analyses of randomised trials find 400 mg/day riboflavin for 3 months reduces migraine days by roughly 1-2 per month versus placebo, with the strongest signal in adults rather than children. Results are heterogeneous and several individual trials were null, so this is a low-cost option rather than a first-line therapy. It appears in some neurology guidelines as a possible preventive.

  • Prevents migraine in children and adolescents Limited evidence

    Paediatric RCTs of riboflavin have largely failed to separate from placebo, and network meta-analyses of paediatric migraine prophylaxis do not rank it favourably. The adult signal does not transfer.

  • Improves energy, skin, or exercise performance Limited evidence

    Riboflavin is a precursor to FAD and FMN in mitochondrial electron transport, which is the mechanistic pitch, but there are no controlled trials showing improved energy or performance in people with normal riboflavin status. Deficiency causes angular cheilitis, glossitis and sore throat, and correcting that resolves the symptoms — nothing more.

  • Lowers blood pressure in people with the MTHFR 677TT genotype Limited evidence

    Small trials in people homozygous for the MTHFR C677T variant found 1.6 mg/day riboflavin lowered systolic blood pressure by around 5-13 mmHg, an unusually large effect that has not been replicated in larger, genotype-unselected populations. Interesting, but not yet actionable.

Dosage & safety

Studied doseRDA is 1.3 mg/day for men and 1.1 mg/day for women. Migraine prophylaxis trials used 400 mg/day for at least 3 months — allow a full 3 months before judging response. Blood pressure work in MTHFR 677TT used 1.6 mg/day. Absorption saturates at roughly 27 mg per dose, so very large single doses are mostly excreted.
SafetyVery safe; no tolerable upper intake level has been set because no toxicity has been demonstrated even at 400 mg/day. Produces bright yellow urine, which is harmless and expected — many people mistake it for a sign the supplement is 'working' or being wasted. Rare mild diarrhoea or increased urination. No significant drug interactions, though anticholinergics and probenecid may increase absorption. Not banned in sport.

How to take it

TimingTiming does not matter, but split a 400 mg migraine dose into two — absorption saturates around 27 mg per dose, so a single large tablet is mostly wasted.
With food?With food, which meaningfully improves absorption.
Worth knowingBright yellow urine just means the excess is being excreted — it is not evidence the supplement is working, and not a reason to lower the dose.

Frequently asked questions

Does riboflavin work for migraines?

In adults, the evidence for riboflavin is moderate: trials of 400 mg/day for 3 months cut migraine days by about 1–2 per month versus placebo. Results vary and several trials were null, so riboflavin is a low-cost option rather than first-line therapy.

How much riboflavin per day for migraines?

Migraine trials used 400 mg/day of riboflavin (vitamin B2) for at least 3 months, so allow the full 3 months before judging. Split the riboflavin dose in two and take it with food, since absorption saturates at roughly 27 mg per dose.

Why does vitamin B2 turn urine bright yellow?

Bright yellow urine is excess riboflavin being excreted, which is harmless and expected. It is not a sign vitamin B2 is working, and not a reason to lower the dose.

Does riboflavin work for migraines in children?

Apparently not — the evidence is limited. Paediatric trials of riboflavin have largely failed to beat placebo, so the adult signal does not transfer.

Scientific references

Where to buy

Seeking Health, Riboflavin, 400 mg, 60 Capsules

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