riboflavine

Riboflavin, also known as riboflavine or vitamin B2, is a water-soluble vitamin essential for human health. It acts as a precursor to the redox-active coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which participate in numerous oxidation–reduction reactions throughout energy metabolism.

In the body, riboflavin-dependent enzymes support the metabolism of carbohydrates, fats, and proteins, help maintain the cellular redox state, and assist in the regeneration of other vitamins such as vitamin B6 and vitamin B3. FMN and FAD are involved in the electron transport chain and in various dehydrogenase reactions, contributing to ATP production and overall energy yield.

Dietary riboflavin is widely available in foods such as dairy products, eggs, meat, organ meats, green leafy vegetables, and fortified cereals. It is sensitive to light and is often provided in opaque packaging to preserve potency. The body absorbs riboflavin in the small intestine and converts it to FMN and then to FAD through specific kinases; these coenzymes function in many tissues, particularly in the liver and the mitochondria. Excess riboflavin is excreted in urine.

Deficiency, known as ariboflavinosis, is uncommon in developed countries but can occur with poor diet, malabsorption, or chronic illness. Symptoms include sore throat, cracked lips, angular stomatitis, a swollen magenta tongue, dermatitis, and sensitivity to light. People at risk include those with restricted diets, alcohol dependence, or certain medical conditions.

Riboflavin supplements are used to treat deficiency and may be included in multivitamin preparations. High-dose riboflavin has been studied for migraine prophylaxis, with mixed results. There is no established toxicity from typical dietary intake, and adverse effects are rare.