Riboflavin 5'-Phosphate
Also called Active B2 / FMN precursor
Riboflavin 5'-phosphate is the active form of B2 and serves as a direct precursor to FMN. It may be preferable for people with genetic variants affecting riboflavin activation, though direct comparative trials are limited. It is usually more expensive than standard riboflavin.
Best for
People with suspected MTHFR or mitochondrial issues
Absorption
High
Tolerability
Generally well tolerated
Typical timing
Morning or divided with meals; high doses with food
How to take Riboflavin 5'-Phosphate
A typical dose of Vitamin B2 (Riboflavin): 1–1.5 mg RDA; 200–400 mg for migraine prevention. Best timing: Morning or divided with meals; high doses with food. The form you choose mainly affects absorption and how easily it sits with your stomach, not the overall dose.
Where to buy Riboflavin 5'-Phosphate
Choose a third-party-tested brand; the label should name this form explicitly.
Some links below are affiliate links: if you buy through them we may earn a small commission at no extra cost to you. It never changes our ratings or evidence grades.