Vitamin B2 (Riboflavin)
Essential Vitamins & Minerals · 8 specs
Direct Answer
Vitamin B2 is an essential water-soluble isoalloxazine vitamin serving as the core structural component of Flavin Mononucleotide (FMN) and Flavin Adenine Dinucleotide (FAD) coenzymes in cellular redox respiration. Adult RDA is 1.3 mg (men) / 1.1 mg (women).
Source: NIH ODS / EFSA · Last reviewed Aug 28, 2026
Specs
| Nutrient Type | Water-Soluble Isoalloxazine Vitamin |
| Adult RDA / RDI | 1.3 mg / day (Men) / 1.1 mg / day (Women) |
| Tolerable Upper Limit (UL) | None Established (Saturates intestinal absorption at ~27mg; excreted as harmless bright yellow urine) |
| Chemical Forms | Riboflavin, Riboflavin-5'-Phosphate (FMN), Flavin Adenine Dinucleotide (FAD) |
| Primary Biological Function | Complex I and Complex II mitochondrial electron transport chain cytochromes, Glutathione Reductase, B6/Folate activation |
| Deficiency Condition | Ariboflavinosis (Angular cheilitis / cracked lip corners, glossitis / magenta tongue, seborrheic dermatitis) |
| Top Whole Food Sources | Beef Liver, Dairy Milk, Greek Yogurt, Eggs, Almonds, Portobello Mushrooms, Spinach |
| Photodegradation Vulnerability | Extremely light-sensitive (dairy milk stored in clear glass loses 50% riboflavin within 2 hours of sunlight exposure) |
FAD & Glutathione Antioxidant Regeneration
Riboflavin in the form of FAD is the mandatory prosthetic coenzyme for glutathione reductase, regenerating reduced glutathione (GSH) to defend cells against reactive oxygen species.
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