Vitamin B2 (Riboflavin)

Your intake

What each level of vitamin b2 (riboflavin) does

Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.

1. Severely lowYOU ARE HERE

   0 mg – 0.43 mg

   Well below target. Risk of deficiency symptoms tied to energy metabolism.

2. Insufficient

   0.43 mg – 1.3 mg

   Below the recommended daily target. Long-term adequacy not assured.

3. Adequate

   1.3 mg – 1.95 mg

   Daily target met. Standard nutritional support for energy metabolism.

4. Therapeutic

   1.95 mg – 2.6 mg

   Common for specific health goals. Check the evidence for your situation before sustaining this level.

5. Diminishing returns

   2.6 mg – +

   Past the point where extra intake typically helps. Evidence for further benefit is thin.

Overview

Riboflavin is a water-soluble B vitamin and precursor to the flavin coenzymes FMN and FAD. These shuttle electrons in the mitochondrial electron transport chain and serve as cofactors for ~150 enzymes across redox, amino acid, and methylation pathways.

Functions

• ●Forms FAD/FMN — universal electron carriers in oxidative phosphorylation
• ●Cofactor for glutathione reductase (regenerates reduced glutathione)
• ●Required for activation of B6 (to PLP) and folate metabolism
• ●Cofactor in fatty acid beta-oxidation and BCAA catabolism

Mechanism

FAD-dependent enzymes drive electron transfer at complex I and complex II of the ETC. FAD-glutathione reductase maintains the GSH/GSSG ratio that buffers oxidative stress. Riboflavin is also a cofactor for MTHFR — the homozygous 677T variant raises riboflavin demand, and supplementation can lower homocysteine in this subgroup.

Benefits

• ●Reduces migraine frequency at 400 mg/day (3 well-designed trials)
• ●Corrects riboflavin-responsive forms of MTHFR-associated hyperhomocysteinemia
• ●Treatment for inherited multiple acyl-CoA dehydrogenase deficiency
• ●Photodegrades bilirubin in neonatal jaundice phototherapy

Deficiency

Usually subclinical and rarely isolated — typically co-occurs with broader B-vitamin shortfall. Population intake is generally adequate in fortified-grain countries.

Excess

No established UL. Excess is excreted in urine, producing the bright yellow colour typical of B-complex supplements.

Forms

• Riboflavin (free)
  Standard supplement form
• Riboflavin-5-phosphate (R5P/FMN)
  Active coenzyme form; marketed as 'activated' but conversion is rarely rate-limiting
• FAD
  Tissue coenzyme; not used as oral supplement

Food sources

• Beef liver (cooked) · 3 oz2.9 mg
• Fortified cereal · 1 cup0.5–1.7 mg
• Greek yogurt · 1 cup0.5 mg
• Cooked salmon · 3 oz0.5 mg
• Cooked spinach · 1 cup0.4 mg
• Almonds · 1 oz0.3 mg

Supplement forms

Standard riboflavin is fine. Migraine prophylaxis dose is 400 mg/day; expect 2–3 months before benefit is apparent. R5P costs more without meaningful clinical advantage.

Bioavailability

Absorbed in proximal small intestine by a saturable transporter; absorption plateaus around 27 mg per dose. Food (especially with fat) modestly enhances uptake. Sensitive to light — milk in clear plastic bottles loses 50% of riboflavin in 2 hours of fluorescent exposure.

Longevity relevance

Adequacy supports mitochondrial function and glutathione recycling, both relevant to healthy aging. No evidence that megadosing extends lifespan in non-deficient adults.

Relationships

References

• NIH ODS — Riboflavinguideline
• Linus Pauling Institute — Riboflavinreview
• Schoenen — riboflavin migraine RCT (Neurology 1998)study

About Vitamin B2 (Riboflavin)

Cofactor for FAD/FMN; cellular energy production.

Role

Energy metabolism

Daily target

1.3 mg (DV)

Also called

riboflavin, vitamin b2, vitamin b-2, riboflavin 5'-phosphate, r5p