FMN

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What Is FMN?

Supplement

Flavin mononucleotide (FMN), also known as riboflavin-5′-phosphate, is the bioactive form of Vitamin B2 that serves as a vital prosthetic group for mitochondrial oxidoreductases like NADH dehydrogenase. It facilitates essential electron transfer in the respiratory chain and acts as a cofactor for blue-light photoreceptors, playing a critical role in cellular energy metabolism and mitochondrial function.

FMN Research & Studies

01 Riboflavin metabolism: role in mitochondrial function

This review details how riboflavin derivatives like FMN are indispensable for mitochondrial energy production and the maintenance of the electron transport chain.

View Study (PubMed)
02 Flavin mononucleotide

An analysis of FMN as a stronger oxidizing agent than NAD, highlighting its unique ability to participate in both one- and two-electron transfers within cells.

View Study (Wikipedia)

FMN User Reviews & Experiences

85% Positive

*Based on large scale analysis of publicly available user experiences

Users generally view FMN as a superior, more bioavailable form of Vitamin B2 compared to standard riboflavin, specifically noting its efficacy in supporting mitochondrial health and energy levels.

FMN Benefits, Dosage & Side Effects

Effects
  • Mitochondrial Enhancement: FMN supports the electron transport chain, specifically Complex I, to optimize ATP production.
  • Bioactive Energy Support: As the primary form found in tissues, it provides more immediate metabolic support than standard riboflavin.
  • Solubility Benefits: FMN is significantly more water-soluble than basic riboflavin, leading to better absorption and systemic utilization.
Effectiveness
  • Mitochondrial Rescue: Highly effective in clinical contexts for treating mitochondrial diseases and ischemia/reperfusion injury.
  • Bioavailability: Considered more effective for those with riboflavin kinase deficiencies who cannot convert standard B2 efficiently.
  • Fast-Acting: Because it does not require the same metabolic conversion steps as riboflavin, it is utilized more rapidly by cells.
Dosage & Administration
  • Common Supplement Dose: Often found in 'Coenzymated' B-complexes ranging from 10mg to 50mg.
  • Clinical Application: Higher therapeutic doses are used in medical settings for corneal cross-linking or specific metabolic disorders.
  • Enhanced RDA: Intake often exceeds the standard 1.1-1.3mg RDA when used for targeted mitochondrial support.
Side Effects
  • Chromaturia: Harmless bright yellow or neon-orange discoloration of urine due to excess riboflavin excretion.
  • Digestive Comfort: Generally well-tolerated, though high doses may cause mild gastrointestinal upset in sensitive individuals.
  • Rapid Absorption: Unlike standard B2, its high solubility can lead to faster but shorter-lived peaks in serum levels if not taken with food.
Availability & Sourcing
  • Over-the-Counter: Widely available as a dietary supplement often labeled as Riboflavin-5'-Phosphate.
  • FDA Approved: Recently approved in specific formulations (Epioxa) for medical use in treating keratoconus as of October 2025.
  • Food Additive: Commonly found in European food products under the designation E101a.

Related Compounds

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