Riboflavin-5-phosphate (active B2)

Tier 3 — weak evidence · Active B2 · Migraine · Mitochondrial

The phosphorylated coenzyme form of vitamin B2 (FMN), sometimes preferred in patients with MTHFR variants or impaired riboflavin activation. The strongest evidence for riboflavin in any form is for migraine prevention at 400 mg/day standard riboflavin — the active R5P form has limited direct trial data but offers a more bioavailable alternative at lower doses. Generally very safe; harmless bright-yellow urine is universal.

Dose: 25–100 mg R5P daily; for migraine prevention, 400 mg/day standard riboflavin remains the trial-validated dose