🧬 Family & Essentiality

🌿 Plain-Language Summary

Vitamin B2 helps your body release energy from food. It forms two coenzymes — FMN and FAD — that are crucial for converting carbohydrates, fats, and proteins into usable energy. Riboflavin also supports antioxidant defences and helps other vitamins work properly.

⚗️ Molecular & Chemical IDs

• Riboflavin: C₁₇H₂₀N₄O₆ (CAS 83-88-5)
• Properties: Light-sensitive, stable to heat, yellow-orange pigment

⚡ Functions

• Electron transfer via FMN/FAD in mitochondrial energy metabolism (Complex I & II, fatty acid oxidation, TCA cycle)
• Supports glutathione reductase → maintains antioxidant capacity (recycles glutathione)
• Required for metabolism of other vitamins: B6 (PLP activation), niacin (NAD synthesis), folate (MTHFR activity)

🍽️ Absorption & Bioavailability

Cultural note: yoghurt in opaque tubs (Middle Eastern diets) preserves riboflavin better than milk in clear bottles.

🇦🇺 Australian NRVs (NHMRC — RDI)

• Adult men: 1.3 mg/day
• Adult women: 1.1 mg/day
• Pregnancy: 1.4 mg/day
• Lactation: 1.6 mg/day

UL (Upper Level): Not established

🚨 Deficiency & Excess

Deficiency (ariboflavinosis)

• Angular cheilitis (cracks at mouth corners)
• Glossitis (magenta tongue)
• Stomatitis, seborrhoeic dermatitis, eye irritation

Excess

No known toxicity from foods; high-dose supplements cause harmless bright yellow urine.

🥗 Food Sources

• Dairy (milk, yoghurt), eggs
• Lean meats, offal
• Green vegetables, almonds, mushrooms
• Fortified breads and cereals

🧪 Testing & Monitoring

• Functional marker: EGRAC (erythrocyte glutathione reductase activation coefficient)
• Plasma riboflavin or urinary riboflavin provide supportive info
• Testing considered in malnutrition, alcohol misuse, or chronic illness

🔗 Interactions

• Photosensitivity: exposure to light destroys riboflavin in foods/solutions
• Medications: chlorpromazine, tricyclic antidepressants, and some chemotherapy drugs can affect riboflavin status

📊 Evidence Snapshot

• 🔬✅ Well-established: FMN/FAD roles in energy metabolism
• 🧪⚖️ Clinical note: High-dose riboflavin (100–400 mg/day) for migraine prevention should be supervised by a healthcare provider
• ⚠️❌ Unproven/hype: Broad energy/performance claims in already well-nourished individuals