Vitamin B2 (Riboflavin)

What It Is

Vitamin B2, known as riboflavin, is an essential water-soluble vitamin that belongs to the B-complex group. Humans cannot produce it in meaningful amounts and must obtain it from diet or supplementation. It is found naturally in foods such as dairy, eggs, organ meats, almonds, fortified cereals, leafy greens and some mushrooms. Being water soluble, excess amounts are excreted in urine rather than stored, which is why intake must be regular.

How It Works

Riboflavin acts primarily as a precursor to two coenzymes—FAD (flavin adenine dinucleotide) and FMN (flavin mononucleotide)—which support dozens of oxidation-reduction reactions throughout metabolism. In practical terms, these coenzymes help convert carbohydrates, fats, and proteins into cellular energy (ATP), assist in antioxidant regeneration (notably helping recycle glutathione), and support mitochondrial integrity. Riboflavin also plays a role in maintaining normal function of the skin, eyes, mucous membranes, iron metabolism and in the translation of dietary vitamin B6, folate and niacin into their active forms.

Why It’s Important

Adequate riboflavin is crucial for energy metabolism, nervous system function, and red blood cell maintenance. It contributes indirectly to DNA repair and cell protection by maintaining the antioxidant defense system. Clinically, riboflavin has been used in high-dose regimens for migraine prevention, likely through mitochondrial stabilization. Deficiency (called ariboflavinosis) can manifest as fatigue, weakness, mouth corner cracking (angular cheilitis), sore throat, skin inflammation, tongue redness and discomfort, eye irritation or light sensitivity. Sub-optimal intake may go unnoticed but still impair energy output and antioxidant tone.

Considerations

Because riboflavin is water soluble, toxicity is essentially absent even at high doses, though urine commonly turns bright yellow when intake is high—this is benign. People with restricted diets (vegan diets without fortified foods, under-eating, eating disorders, or low-dairy intakes) are at higher risk of insufficient intake. Chronic malabsorption, alcoholism, advanced age, and certain genetic variants affecting flavoprotein activity can increase requirements. Riboflavin status is also relevant in individuals supplementing iron, folate or B6, since riboflavin supports their utilization; if riboflavin is inadequate, response to these nutrients may be blunted. Finally, high-dose supplementation for migraine is usually done under clinician direction because the target dose (often 200–400 mg per day) is far above dietary intake and is taken for a defined clinical purpose.