Vitamin B2
Riboflavin (Vitamin B2)
Riboflavin (Vitamin B2) is a water-soluble B-vitamin essential for energy metabolism, cellular respiration, and the activation of other B vitamins. It is widely used to address dietary deficiency, support mitochondrial function, and at high doses (400mg/day) is clinically validated for migraine prophylaxis.
Mechanism of Action
Riboflavin serves as the precursor to two critical coenzymes—flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)—which act as electron carriers in the mitochondrial electron transport chain and are required for oxidative phosphorylation. These coenzymes are also essential for the metabolism of fats, carbohydrates, and amino acids, and for the regeneration of glutathione via glutathione reductase, supporting antioxidant defense. Additionally, riboflavin is required for the conversion of vitamin B6 to its active form (pyridoxal-5-phosphate) and for folate metabolism.
Evidence by Health Goal(17 goals)
Dosing Protocols
With meals
Standard dietary reference intake for adults; sufficient to prevent deficiency and support general metabolic health. Found in most multivitamins and B-complex formulations.
With meals to improve absorption
High-dose protocol validated in clinical trials for migraine prophylaxis; effect typically seen after 3 months of consistent use. Urine will turn bright yellow at this dose, which is harmless.
Safety & Side Effects
Riboflavin has an excellent safety profile and is considered non-toxic even at high therapeutic doses (400mg/day), as excess is rapidly excreted in urine due to its water-soluble nature; no established tolerable upper intake level has been set by major health authorities. It is available over the counter in all major markets and poses minimal risk when used as directed.
Possible Side Effects
- !Bright yellow-orange discoloration of urine (harmless, nearly universal at doses above 10mg)
- !Nausea or gastrointestinal discomfort at high doses (400mg)
- !Diarrhea with prolonged high-dose use
- !Photosensitivity of skin in rare cases
- !Itching or mild skin flushing at very high doses
Interactions
- -Tricyclic antidepressants (e.g., amitriptyline) may impair riboflavin absorption and reduce its efficacy
- -Certain antipsychotics (phenothiazines such as chlorpromazine) can reduce riboflavin availability by inhibiting its conversion to active coenzymes
- -Probenecid (gout medication) may inhibit renal tubular secretion of riboflavin, potentially altering levels
- -Alcohol consumption chronically impairs riboflavin absorption and increases deficiency risk
- -Combined use with other B-complex vitamins (B6, B12, folate) is synergistic and generally recommended for comprehensive B-vitamin support
Cost & Where to Buy
Standard-dose B2 supplements are very affordable; high-dose 400mg formulations for migraine prevention cost slightly more but remain inexpensive. Price varies by brand, dose, and whether purchased standalone or as part of a B-complex.
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