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Riboflavin

Evidence Level
Strong
8 Clinical Trials
8 Documented Benefits
4/5 Evidence Score

Riboflavin (vitamin B2) is an essential water-soluble vitamin central to energy production and to recycling antioxidants such as glutathione. It also helps activate other B vitamins, including B6 and folate. Adequate amounts are easily obtained from dairy, eggs, lean meats, and fortified grains, so deficiency is uncommon, but supplements are used for general energy support and, at a higher dose of around 400 mg per day, have been studied for people prone to migraines. Riboflavin is considered very safe because excess is excreted, which harmlessly turns urine bright yellow, a normal and expected effect rather than a cause for concern.

Studied Dose 1.1–1.3 mg/day (RDA); migraine prevention: 400 mg/day (clinical studies); metabolic support: 10–50 mg/day
Active Compound Vitamin B2 (Riboflavin / R-5-P)
Deficiency information View details

Riboflavin (vitamin B2) deficiency, also called ariboflavinosis, is extremely rare in the US but can occur in people with very limited diets, alcohol use disorder, or specific genetic disorders. Riboflavin deficiency rarely occurs alone — it usually appears alongside deficiencies of other B vitamins.

Common symptoms

  • Cracks at the corners of the mouth (angular stomatitis)
  • Swollen, cracked lips (cheilosis)
  • Sore throat
  • Magenta-colored, swollen tongue (glossitis)
  • Skin disorders, including seborrheic dermatitis around the nose and mouth
  • Itchy, red, or bloodshot eyes; sensitivity to light
  • Hair loss
  • Fatigue from associated normocytic anemia

At-risk groups

  • People with alcohol use disorder (poor intake plus impaired absorption)
  • People with very limited diets or anorexia
  • Strict vegans avoiding all dairy and fortified foods (dairy is a major source)
  • Pregnant and breastfeeding women with poor intake
  • Adolescents during growth spurts who skip breakfast
  • Athletes with extremely high energy expenditure and poor diet
  • People with malabsorption conditions
  • People with rare inherited disorders affecting riboflavin transport
When to see a doctor: Persistent cracks at the corners of the mouth, recurrent sore throat with swollen tongue, or seborrheic dermatitis that doesn't respond to standard treatment may warrant evaluation for B-vitamin deficiencies. A dietitian or doctor can assess intake and order targeted testing.
Explore related deficiencies →
Sources: NIH ODS — Riboflavin Health Professional Fact Sheet · Riboflavin Deficiency — StatPearls (NBK470460)

Benefits

Migraine Prevention

High-dose riboflavin (400 mg/day for adults, 200 mg/day for children) reduces migraine frequency and severity by about two attacks per month. Benefits typically appear after 1–3 months with minimal side effects.

Supported by Trial 1, Trial 2

Energy Metabolism

Riboflavin is a precursor to flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), coenzymes critical for carbohydrate, protein, and fat metabolism. It supports energy production in cells, particularly in mitochondria. Enhances overall energy levels and cellular function, especially in active tissues like muscles and the heart.

Supported by Trial 6, Trial 4

Cardiovascular Health

In individuals with the MTHFR 677TT genotype, low-dose riboflavin (1.6 mg/day) lowers systolic blood pressure by 6–13 mm Hg and reduces homocysteine levels, a risk factor for heart disease.

Supported by Trial 6

Eye Health

Riboflavin supports glutathione reductase activity, protecting lens proteins from oxidative damage. Combined with niacin, it may reduce the risk of nuclear cataracts.

Supported by Trial 4, Trial 1

Neurological Disorders

High-dose riboflavin is a mainstay treatment for multiple acyl-CoA dehydrogenase deficiency (MADD) and other mitochondrial disorders caused by gene mutations (e.g., ETFDH, ACAD9), improving muscle function and energy metabolism.

Supported by Trial 8

Skin and Mucous Membrane Health

Riboflavin deficiency can cause cheilosis (cracked lips), angular stomatitis, and dermatitis. Adequate intake supports healthy skin, lips, and mucous membranes. Maintains tissue integrity, particularly in high-turnover areas.

Supported by Trial 8, Trial 1

Red Blood Cell Production

Riboflavin supports erythrocyte production and iron metabolism, potentially reducing anemia risk when combined with other nutrients.

Supported by Trial 5, Trial 1

Antioxidant Support

As a component of glutathione reductase, riboflavin helps regenerate glutathione, a key antioxidant, protecting cells from oxidative stress. May reduce oxidative damage in conditions like cataracts or neurological diseases.

Supported by Trial 8

Mechanism of action

1

Coenzyme Role

Riboflavin is converted into FMN and FAD, which serve as coenzymes in redox reactions. These coenzymes act as electron carriers in enzymatic reactions, facilitating the transfer of electrons in metabolic pathways.

2

Energy Metabolism

FMN and FAD are essential for the function of flavoproteins, which are involved in the metabolism of carbohydrates, fats, and proteins. They participate in the electron transport chain, contributing to ATP production via oxidative phosphorylation.

3

Enzyme Cofactor

FAD and FMN are cofactors for enzymes like glutathione reductase, which maintains reduced glutathione levels for antioxidant defense, and succinate dehydrogenase, a key enzyme in the citric acid cycle.

4

Antioxidant Support

By supporting glutathione reductase, riboflavin indirectly protects cells from oxidative stress by maintaining the antioxidant glutathione in its reduced form.

5

Other Functions

Riboflavin-dependent enzymes are involved in the metabolism of other B vitamins (e.g., vitamin B6 and folate) and the synthesis of niacin from tryptophan.

Clinical trials

1
Riboflavin for Migraine Prophylaxis — Schoenen Clinical Trial

Randomized, double-blind, placebo-controlled trial in 55 adults with recurrent migraines receiving riboflavin (400 mg/day) vs placebo for 3 months. Outcomes: migraine frequency, duration, intensity. (Neurology)

55 adults with recurrent migraines.

Riboflavin reduced migraine frequency by ~50% vs placebo. AHS/AAN guidelines (2012) recommend riboflavin (Level B) for migraine prevention. Generally well-tolerated; bright yellow urine is harmless cosmetic effect.

2
High-Dose Riboflavin for Pediatric Migraine — Clinical Trial

Double-blind, randomized, placebo-controlled trial in children with migraines receiving 200 mg/day riboflavin vs placebo. (MacLennan et al. 2008, J Child Neurol; or related)

Pediatric migraine patients.

Mixed results in pediatric trials — some trials showed benefit, others negative. Pediatric migraine evidence less robust than adult. NHS UK guidance suggests riboflavin trial reasonable; not all children respond.

3
Riboflavin as Medication Adherence Biomarker — Trial

2-year clinical trial assessing riboflavin as a biomarker for medication adherence in clinical trials. Outcomes: urinary riboflavin as proxy for compliance.

Trial participants.

Riboflavin's distinctive urinary excretion provides reliable adherence biomarker — pharmaceutical applications use this property. Note: this is a methodologic application, not a clinical efficacy trial.

4
Riboflavin as Surrogate Marker for BCRP Activity — Pilot

Pilot study evaluating riboflavin as endogenous biomarker for Breast Cancer Resistance Protein (BCRP/ABCG2) activity. (2024)

Pharmacokinetic research participants.

Riboflavin shows promise as BCRP activity marker — relevant for drug-drug interaction research. Pharmacology methodology paper, not clinical efficacy.

5
Multivitamin Effects on Plasma Nutrients (China) — Clinical Trial

Randomized, double-blind, controlled trial in China examining multivitamin/mineral supplements on plasma B-vitamin levels. Outcomes: riboflavin, B12, folate, etc.

Chinese adults.

Multivitamin supplementation increased plasma B-vitamin levels. Establishes that supplementation effectively raises micronutrient levels — basic but useful confirmation.

6
Riboflavin for MTHFR 677TT Genotype — Clinical Trial

Clinical trials examining riboflavin (1.6 mg/day for 12 weeks) effects on homocysteine and BP in patients with MTHFR C677T variant.

MTHFR 677TT genotype patients.

Riboflavin supplementation improved homocysteine levels and lowered BP in MTHFR 677TT genotype carriers. Critical context: MTHFR variants are common (~10-20% of population); riboflavin is cofactor for MTHFR enzyme — supplementation can rescue impaired methylation. This finding has clinical relevance for genotype-targeted nutrition.

7
Riboflavin for Pediatric Migraine — Multiple Studies Review

Review of 7 studies (4 clinical trials) evaluating riboflavin's role in pediatric migraine prevention. (2021)

Pediatric migraine literature.

Riboflavin modestly effective in pediatric migraine prevention but evidence less consistent than adult evidence. AAP/AAN guidance: reasonable trial; not first-line.

8
Riboflavin in Neurological Diseases — Review

Narrative review summarizing clinical trials and studies on riboflavin's therapeutic use in neurological disorders. (2021)

Pooled neurological literature.

Riboflavin shows therapeutic role in: migraine, MELAS syndrome (mitochondrial encephalopathy), Brown-Vialetto-Van Laere syndrome (riboflavin transporter deficiency), some pediatric neurological disorders. Specific mitochondrial neurological conditions are most established applications beyond migraine.

Side effects and drug interactions

Common Potential side effects

Urine Discoloration: The most common side effect is bright yellow or orange urine due to the excretion of excess riboflavin, which is harmless.
Gastrointestinal Issues: High doses (e.g., >100 mg/day) may cause mild symptoms like nausea, diarrhea, or stomach discomfort in some individuals.
Allergic Reactions: Rare cases of hypersensitivity or allergic reactions, such as itching, rash, or swelling, have been reported with large doses.
Photosensitivity: In very rare cases, excessive riboflavin intake may increase sensitivity to sunlight, potentially leading to skin reactions.

Important Drug interactions

Potential Drug Interactions: High doses might interfere with certain medications (e.g., tetracycline antibiotics) or affect the efficacy of other B vitamins by altering their metabolism.

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Frequently asked questions about Riboflavin

How much riboflavin (B2) should I take?

The RDA is about 1.1 to 1.3 mg per day. Supplements often contain far more (25 to 100 mg, or 400 mg for migraine support). It is water-soluble and very safe, with excess simply excreted.

Why does riboflavin turn urine bright yellow?

Riboflavin (vitamin B2) is naturally bright yellow, and the body excretes what it does not use, which harmlessly turns urine vivid yellow. It is a normal, expected effect, not a sign of a problem.

What is riboflavin used for?

Riboflavin is essential for energy production and helps recycle antioxidants like glutathione. At a higher dose of 400 mg per day it has been studied for supporting people who are prone to migraines.

Is riboflavin safe?

Yes, riboflavin is considered very safe even at high doses because it is water-soluble and not stored in large amounts. The main visible effect is bright yellow urine, which is harmless.

What is Riboflavin?

Riboflavin (vitamin B2) is an essential water-soluble vitamin central to energy production and to recycling antioxidants such as glutathione. It also helps activate other B vitamins, including B6 and folate.

What are the signs of Riboflavin deficiency?

Riboflavin (vitamin B2) deficiency, also called ariboflavinosis, is extremely rare in the US but can occur in people with very limited diets, alcohol use disorder, or specific genetic disorders. Riboflavin deficiency rarely occurs alone — it usually appears alongside deficiencies of other B vitamins.

What is the recommended dosage of Riboflavin?

The clinically studied dose is 1.1–1.3 mg/day (RDA); migraine prevention: 400 mg/day (clinical studies); metabolic support: 10–50 mg/day Always follow the product label and check with a healthcare provider for personal advice.

Is Riboflavin safe, and does it have side effects?

For most healthy adults, Riboflavin is well tolerated at studied doses. Reported effects can include: Urine Discoloration: The most common side effect is bright yellow or orange urine due to the excretion of excess riboflavin, which is harmless. Gastrointestinal Issues: High doses (e.g. It may also interact with some medications. Riboflavin is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Riboflavin interact with any medications?

Possible interactions include: Potential Drug Interactions: High doses might interfere with certain medications (e.g., tetracycline antibiotics) or affect the efficacy of other B vitamins by altering their metabolism. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Riboflavin?

NutraSmarts rates the evidence for Riboflavin as Strong (4 out of 5). It is backed by 8 clinical trials and 4 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(4 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Schoenen J, Jacquy J, Lenaerts M. Effectiveness of high-dose riboflavin in migraine prophylaxis. A randomized controlled trial. Neurology. 1998;50(2):466-70. doi: 10.1212/wnl.50.2.466.PubMedUsed to support: Landmark RCT: riboflavin 400 mg/d for 3 months reduced migraine attack frequency and headache days versus placebo (responder rate 59% vs 15%). Primary support for high-dose riboflavin in adult migraine prophylaxis.
  2. Bruijn J, Duivenvoorden H, Passchier J, Locher H, Dijkstra N, Arts WF. Medium-dose riboflavin as a prophylactic agent in children with migraine: a preliminary placebo-controlled, randomised, double-blind, cross-over trial. Cephalalgia. 2010;30(12):1426-34. doi: 10.1177/0333102410365106.PubMedUsed to support: Pediatric RCT (medium-dose riboflavin) that found NO significant reduction in migraine frequency, duration, or severity versus placebo in children. Important honesty counterpoint: the adult benefit has not replicated consistently in children.
  3. Thompson DF, Saluja HS. Prophylaxis of migraine headaches with riboflavin: A systematic review. J Clin Pharm Ther. 2017;42(4):394-403. doi: 10.1111/jcpt.12548.PubMedUsed to support: Systematic review of 11 trials: riboflavin showed a consistent prophylactic benefit in adults (5 trials) but mixed/inconsistent results overall, especially in pediatric trials. Supports adult migraine prevention while honestly noting heterogeneity; riboflavin is well tolerated and inexpensive.
  4. Powers HJ. Riboflavin (vitamin B-2) and health. Am J Clin Nutr. 2003;77(6):1352-60. doi: 10.1093/ajcn/77.6.1352.PubMedUsed to support: Authoritative review of riboflavin's role as a precursor of the flavocoenzymes FMN and FAD in energy metabolism, and the clinical features of deficiency (ariboflavinosis). Supports the essential cofactor/deficiency-correction role, including interactions with iron handling and other B vitamins.