Riboflavin, or vitamin B2, is a water-soluble vitamin that serves as a key component of two coenzymes: flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). These coenzymes, known as flavocoenzymes, are essential for various oxidation-reduction (redox) reactions in the body. Flavocoenzymes are crucial for metabolizing carbohydrates, fats, and proteins, and FAD plays a critical role in the mitochondrial electron transport chain, which is essential for energy production. Additionally, flavocoenzymes, in conjunction with the cytochrome P-450 enzyme system, help metabolize drugs and toxins.
Riboflavin, also known as vitamin B2, functions as a prosthetic group for the nucleotides flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These coenzymes are crucial for oxidative enzyme systems involved in electron transport and play significant roles in energy production, cellular function, growth, development, and the metabolism of fats, drugs, and steroids.
Riboflavin deficiencies often lead to fatigue due to its role in the formation of adenosine triphosphate (ATP). Additionally, these coenzymes are vital for the dehydrogenation of fatty acids and the conversion of L-amino acids to alpha-keto acids. FAD also supports the glutathione reductase enzyme system, which maintains reduced glutathione.
Riboflavin is primarily absorbed in the proximal small intestine, with limited absorption from single doses over 27 mg. The body stores small amounts in the liver, heart, and kidneys, with 60% being protein-bound after administration and a plasma half-life of approximately 75 minutes.
Indications:
- Riboflavin is essential for ongoing macronutrient metabolism and can improve iron status in patients with iron deficiency.
- Some studies suggest riboflavin may help prevent DNA damage caused by carcinogens by acting as a coenzyme with various cytochrome P450 enzymes, though data on cancer prevention or treatment is limited and mixed.
Warnings:
Premature infants who received excess riboflavin have experienced photohemolysis when exposed to light sources used to treat hyperbilirubinemia.