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📰Read the full Riboflavin evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.⚠ Angular stomatitis + glossitis — classic ariboflavinosis. Common in alcoholism, veganism without supplementation, and elderly [3]
⚠ Anemia refractory to iron therapy — consider riboflavin deficiency as the underlying cause [2]
⚠ Patient with MTHFR 677TT genotype and elevated homocysteine — riboflavin (1.6 mg/day) may be as important as folate [6]
⚠ Migraine patients — offer riboflavin 400 mg/day before prescribing more costly or toxic prophylactics [4]
🥗 Food first — build your daily 1.3 mg/ 1.1 mg
Check the foods you regularly eat — the bar fills toward your daily target.
Beef liver (85g)2.9 mg
Fortified cereals (1 serving)1.3 mg
Yogurt (1 cup)0.5 mg
Milk (1 cup)0.4 mg
Mushrooms (½ cup)0.2 mg
Almonds (28g)0.3 mg
Egg (1 large)0.2 mg
Check your regular foods above
☑ Risk checker
Low dairy intake (vegans, lactose intolerance without alternatives) [3]
Chronic alcoholism [2]
Anorexia nervosa and restrictive eating disorders [3]
Elderly with poor dietary diversity [3]
Phototherapy in neonatal jaundice (degrades riboflavin) [1]
Hypothyroidism (may impair conversion to FAD) [2]
MTHFR 677TT genotype (increased riboflavin demand) [6]
Select factors
🔬 Lab interpreter
Recommended test
Erythrocyte glutathione reductase activity coefficient (EGRAC)
Erythrocyte glutathione reductase activity coefficient (EGRAC)
Reference range / target
<1.20 normal; 1.20–1.40 marginal; >1.40 deficient
<1.20 normal; 1.20–1.40 marginal; >1.40 deficient
The gold standard functional biomarker. Measures the degree to which exogenous FAD stimulates glutathione reductase in erythrocytes [2].
Full lab monitoring ↓⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
Riboflavin is the 'silent enabler' — its deficiency impairs folate, niacin, and iron metabolism. High-dose riboflavin (400 mg/day) is an evidence-based migraine prophylaxis with minimal side effects. In patients with the MTHFR 677TT genotype, riboflavin is a critical cofactor for homocysteine metabolism [2] [4] [6].
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: Specific dosage data under clinical review
👦 Pediatric: See guidance
Infants 0–6 months: 0.3 mg/day AI; 7–12 months: 0.4 mg/day. Children 1–3 years: 0.5 mg/day; 4–8 years: 0.6 mg/day [1]. Deficiency in children manifests as angular stomatitis, glossitis, and gr
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Specific dosage data under clinical review
How to take
🍽 Timing: Take with food to enhance absorption. Can be taken at any time of day [1].
💊 With food: Food increases absorption. No specific fat requirement (water-soluble vitamin) [1].
🚫 Avoid: Keep away from light — riboflavin supplements degrade with UV exposure. Alcohol impairs absorption and utilization [2].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['Riboflavin', 'common', 'Free riboflavin. Absorbed in the proximal small intestine via active transport (RFVT). Absorption saturates at approximately 27 mg per single dose [1].'] | Standard | Check label | |
| ["Riboflavin-5'-phosphate (FMN)", 'preferred', 'Pre-activated form. May have slightly higher bioavailability than free riboflavin. Rapidly converted to FAD in tissues [1].'] | Standard | Check label | |
| ['FAD (flavin adenine dinucleotide)', '', 'Coenzyme form found naturally in food. Hydrolyzed to riboflavin in the gut before absorption [1].'] | Standard | Check label |
3 Common questions
Why does my urine turn bright yellow after taking riboflavin? ▼
Excess riboflavin beyond tissue needs is rapidly excreted in urine, producing the characteristic bright yellow color (flavinuria). This is completely harmless and actually indicates adequate absorption and normal kidney function [2].
Can riboflavin help prevent migraines? ▼
Yes — high-dose riboflavin (400 mg/day) has been shown to reduce migraine frequency by approximately 50% in a clinical trial [4]. It is included in several clinical practice guidelines as a migraine prophylaxis option with minimal side effects.
Is riboflavin destroyed by light? ▼
Yes. Riboflavin is highly photosensitive. Milk in clear glass or plastic containers can lose 50–70% of its riboflavin within 24 hours of light exposure [1]. Store dairy products in opaque containers and keep supplements away from light.
Do vegetarians and vegans get enough riboflavin? ▼
Lacto-ovo vegetarians usually meet requirements through dairy and eggs. Vegans are at higher risk of deficiency unless they consume fortified foods, mushrooms, or almonds regularly [3]. Fortified plant milks and cereals are practical alternatives.
4 Clinical evidence
Strong
Treatment and prevention of ariboflavinosis (angular stomatitis, glossitis, seborrheic dermatitis, normochromic normocytic anemia) [3]. Essential cofactor role in the metabolism of folate (MTHFR requires FAD), niacin, and pyridoxine — riboflavin deficiency impairs the function of these vitamins [2]. HIGH
Moderate
Migraine prophylaxis: 400 mg/day reduced migraine frequency by approximately 50% in a randomized trial (n = 55) [4]. This dose is included in multiple clinical guidelines for migraine prevention. Preeclampsia risk reduction in MTHFR TT genotype carriers supplemented with riboflavin [6]. Cataract risk reduction: some observational data suggest inverse association with riboflavin intake [2]. MODERATE
Insufficient
5 Safety, toxicity & adverse events
Relative
⚠ No significant contraindications. Riboflavin is one of the safest B vitamins — excess is excreted in urine (causing harmless fluorescent yellow color).
🚩 Red flags
● Angular stomatitis + glossitis + seborrheic dermatitis — classic ariboflavinosis triad [3]
● Iron-deficiency anemia not responding to iron therapy — assess riboflavin status (required for iron metabolism) [2]
● Neonate undergoing phototherapy with declining riboflavin — monitor and consider supplementation [1]
● Patient with elevated homocysteine despite folate supplementation — check riboflavin status (MTHFR cofactor) [6]
6 Interactions
Drug interactions
Phenobarbital and other barbiturates Moderate
Mechanism: Barbiturates induce hepatic enzymes that increase riboflavin catabolism. [3]
Effect: Reduced riboflavin status with chronic use. [3]
Action: Monitor for signs of deficiency. Consider B-complex supplementation [3].
Tricyclic antidepressants (amitriptyline, imipramine) Moderate
Mechanism: May inhibit riboflavin conversion to FAD and FMN. [3]
Effect: Subclinical riboflavin depletion with long-term use. [3]
Action: B-complex supplementation during chronic TCA therapy [3].
Probenecid Minor
Mechanism: Decreases gastrointestinal absorption and increases renal excretion of riboflavin. [3]
Effect: Mild reduction in riboflavin status. [3]
Action: Ensure adequate dietary riboflavin intake. Supplement if needed [3].
Methotrexate Minor
Mechanism: Folate antagonist that indirectly increases demand for riboflavin (cofactor for folate metabolism). [2]
Effect: May exacerbate subclinical riboflavin deficiency. [2]
Action: Include riboflavin in B-vitamin supplementation during methotrexate therapy [2].
Supplement synergies
Iron · As per deficiency protocol
Riboflavin (as FAD) is required for the mobilization and utilization of stored iron. Deficiency impairs iron metabolism and can cause anemia refractory to iron therapy alone [2].
Riboflavin (as FAD) is required for the mobilization and utilization of stored iron. Deficiency impairs iron metabolism and can cause anemia refractory to iron therapy alone [2].
Folate · 400–800 µg/day folate
Riboflavin (as FAD) is an essential cofactor for MTHFR, the enzyme that activates folate. Co-supplementation optimizes folate metabolism, particularly in MTHFR 677TT carriers [6].
Riboflavin (as FAD) is an essential cofactor for MTHFR, the enzyme that activates folate. Co-supplementation optimizes folate metabolism, particularly in MTHFR 677TT carriers [6].
Niacin · As per protocol
Riboflavin (as FAD) is required by kynurenine mono-oxygenase in the tryptophan-to-niacin conversion pathway [1].
Riboflavin (as FAD) is required by kynurenine mono-oxygenase in the tryptophan-to-niacin conversion pathway [1].
7 Regulatory
United States (FDA): Classified as a dietary supplement. Mandatory fortification of enriched grain products. No UL established due to limited absorption and rapid renal clearance [1].
European Union (EFSA): Authorized health claims for energy metabolism, nervous system function, maintenance of mucous membranes and skin, red blood cell formation, iron metabolism, and vision [7]. No UL established.
Japan (MHLW): Eligible for Foods with Function Claims. Recommended intake: 1.6 mg/day for adult males. Widely available in OTC supplements.
South Korea (MFDS): Registered health functional food ingredient. Approved claims: energy metabolism and skin health.
8 US supplement products
2,448
on-market products containing Riboflavin (NIH DSLD)
Brands carrying Riboflavin (596)
Click a brand to see its Riboflavin products.
9 Frequently paired with
10 Cite this page
Vancouver: Pkhakadze G. Riboflavin — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Aug 15]. Available from: https://supplement.ge/ingredients/riboflavin/
APA 7th: Pkhakadze, G. (2026). Riboflavin — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/riboflavin/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: February 2027
References: 7 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "Riboflavin — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/riboflavin/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG