NutriDex

The Supplement Research Compendium
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Vitamin B2 (Riboflavin)

The flavin cofactor powering cellular energy and redox metabolism

Moderate evidence 🍊Vitamin

✚ Updated · How we grade evidence

Evidence tier
Moderate
Research weight
Citations
11 verified / 11
Classification
Vitamin
❝
What the evidence says. Several controlled trials; effects real but modest or context-dependent.

What is Vitamin B2 (Riboflavin)?

Vitamin B2 (Riboflavin) is a vitamin used for corrects and prevents ariboflavinosis (angular stomatitis, cheilosis, glossitis, dermatitis, sore throat, normocytic anemia). NutriDex grades the human evidence as Moderate. Riboflavin (vitamin B2) is the precursor of the flavin coenzymes FMN and FAD, which are essential for oxidative energy metabolism, the electron transport chain, fatty-acid oxidation, and the metabolism of other micronutrients (folate, vitamin B6, niacin, iron). Frank deficiency (ariboflavinosis) causes angular stomatitis, cheilosis, glossitis, sore throat, normocytic anemia and dermatitis, but is rare in developed countries; correcting it resolves these signs. In non-deficient people the best-supported supplementation benefit is high-dose (400 mg/day) migraine prophylaxis in adults, where small RCTs show reduced attack frequency (NNT ~2.3 in Schoenen 1998), though pediatric results are mixed/null. Blood-pressure lowering is real but restricted to a genetic subgroup (MTHFR 677TT hypertensives); there is no evidence routine riboflavin benefits replete adults beyond these uses.

Purported Benefits

✓Corrects and prevents ariboflavinosis (angular stomatitis, cheilosis, glossitis, dermatitis, sore throat, normocytic anemia)
✓High-dose (400 mg/day) prophylaxis reduces migraine frequency in adults (Schoenen 1998: 59% vs 15% responders, NNT 2.3); pediatric data are mixed/null
✓Lowers blood pressure specifically in hypertensive adults with the MTHFR 677TT genotype (a genotype-targeted, not universal, effect)
✓Required cofactor (as FAD) for the proper metabolism of folate, vitamin B6, niacin and iron, so adequacy supports those pathways
✓Essential for mitochondrial energy production via FMN/FAD in the electron transport chain and fatty-acid oxidation

Evidence by outcome

The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.

OutcomeEvidenceEffectStudies
Ariboflavinosis (deficiency correction)Repletion reliably resolves deficiency signs; established by authoritative DRI bodies rather than RCTs (rare in developed countries). Strong ↑ benefit · large 2
Migraine prophylaxis (adults)High-dose 400 mg/day cut attack frequency (Schoenen NNT 2.3); small RCTs and reviews, well tolerated. Moderate ↑ benefit · moderate 3
Migraine prophylaxis (pediatric)Pediatric data are mixed: a 2025 review found benefit in most comparisons, but earlier trials were null/inconsistent. Mixed ↔ mixed 2
Blood pressure (MTHFR 677TT genotype)Low-dose riboflavin lowers SBP ~5-13 mmHg only in 677TT hypertensives; a genotype-targeted, not universal, effect. Moderate ↑ benefit · moderate 2

Dosing & Compounds

Typical Dose
Adult RDA (US IOM): 1.3 mg/day (men), 1.1 mg/day (women); 1.4 mg (pregnancy), 1.6 mg (lactation). EFSA sets a similar adult Population Reference Intake of 1.6 mg/day. Typical supplement/B-complex doses 1.7-25 mg/day. Migraine prophylaxis dose used in trials: 400 mg/day. No Tolerable Upper Intake Level (UL) has been established, because no adverse effects from high oral intake have been reliably documented and intestinal absorption is limited above ~27 mg per dose.
Active Compounds
Supplement forms: riboflavin (free form), riboflavin-5'-phosphate (FMN); commonly in B-complex and multivitaminsDietary sources: milk and dairy (major contributor), eggs, organ meats (liver, kidney), lean meats, fortified cereals and breads/flourPlant sources: almonds, mushrooms, spinach and other green vegetables, fortified grains

Safety & Cautions

Very low toxicity; riboflavin is water-soluble and excess is excreted in urine, so no UL is set (IOM/NIH ODS/EFSA). The main visible effect of high doses is bright yellow-orange urine (flavinuria), which is harmless. Photosensitivity is theoretical and not clinically significant from oral intake. Interactions: certain drugs may lower riboflavin status or interact (e.g., anticholinergics and probenecid affecting absorption/excretion; chronic high-dose phenothiazines/tricyclics can impair conversion to coenzymes). Riboflavin is photodegraded—keep supplements away from light. No teratogenic, cardiovascular, or carcinogenic signals are associated with riboflavin, unlike some other vitamins (e.g., beta-carotene in smokers, preformed vitamin A). Educational only — always check with your doctor or pharmacist before combining Vitamin B2 (Riboflavin) with any medicine.

Key Studies ★ 11 studies

Systematic review Martello 2025 (Acta Paediatrica) ✓ Full text
Systematic review of 17 studies found riboflavin (alone or combined) significantly reduced migraine frequency in 7/10 comparisons and migraine days in 3/4 studies in paediatric patients, with few side effects and no negative outcomes.
systematic review Thompson & Saluja 2017 (systematic review) ✓ PubMed
Across trials, high-dose riboflavin (50-400 mg/day) reduced migraine frequency in adults and was well tolerated, though results in children were mixed and more data are needed.
RCT Wilson/McNulty 2013 (targeted RCT) ✓ PubMed
Riboflavin 1.6 mg/day for 16 weeks lowered systolic BP by ~13 mmHg specifically in hypertensive adults with the MTHFR 677TT genotype, with no effect in CT/CC genotypes.
RCT Wilson 2013 (Hypertension) ✓ Full text
Targeted RCT in hypertensive MTHFR 677TT individuals (riboflavin 1.6 mg/d, 16 weeks) showed a systolic BP treatment effect of 5.6 +/- 2.6 mm Hg (P=0.033) over and above antihypertensive drugs; diastolic effect was not significant (PubMed 23608654).
RCT Schoenen 1998 (RCT) ✓ PubMed
400 mg/day riboflavin for 3 months reduced migraine attack frequency vs placebo (responders >=50% improvement: 59% vs 15%, p=0.002; NNT 2.3) in 55 patients.
Review Robblee 2025 (Curr Pain Headache Rep) ✓ Source
Nutraceuticals review concludes riboflavin (vitamin B2) can be recommended for migraine prevention in adults with minimal adverse events, while paediatric efficacy remains unproven (PMID 39853578).
Review Riboflavin in neurological diseases 2025 (PMC) ✓ Full text
Review of riboflavin in neurological disease summarizes therapeutic advances, metabolic cofactor roles, and emerging genetic strategies including high-dose riboflavin's efficacy in migraine and riboflavin transporter deficiency.
review McNulty 2017 (review) ✓ PubMed
Synthesizes RCT evidence that riboflavin lowers blood pressure in a genotype-specific manner (MTHFR 677TT), supporting a personalized-nutrition approach rather than universal benefit.
authoritative body NIH ODS Riboflavin Fact Sheet (authoritative body) ✓ Source
Adult RDA is 1.3 mg (men)/1.1 mg (women); deficiency (ariboflavinosis) is rare in the US, and no UL has been established because high intakes have not produced documented adverse effects.
authoritative body EFSA NDA Panel 2017 (authoritative body) ✓ Full text
Set adult riboflavin Population Reference Intake at 1.6 mg/day (1.9 mg pregnancy, 2.0 mg lactation) and did not establish an upper limit due to lack of evidence of harm from excess intake.
authoritative body IOM DRI (Thiamin, Riboflavin, etc.) 1998 ✓ Full text
Established the adult riboflavin RDA and concluded data were insufficient to set a Tolerable Upper Intake Level, citing limited absorption and absence of reported toxicity.
11 sources cited · 11 verified Search all studies on PubMed ↗

Common questions about Vitamin B2 (Riboflavin)

What is Vitamin B2 (Riboflavin) used for?

Vitamin B2 (Riboflavin) is most often taken for Corrects and prevents ariboflavinosis (angular stomatitis, cheilosis, glossitis, dermatitis, sore throat, normocytic anemia), High-dose (400 mg/day) prophylaxis reduces migraine frequency in adults (Schoenen 1998: 59% vs 15% responders, NNT 2.3); pediatric data are mixed/null, Lowers blood pressure specifically in hypertensive adults with the MTHFR 677TT genotype (a genotype-targeted, not universal, effect), Required cofactor (as FAD) for the proper metabolism of folate, vitamin B6, niacin and iron, so adequacy supports those pathways. The flavin cofactor powering cellular energy and redox metabolism

Does Vitamin B2 (Riboflavin) work — what does the evidence say?

Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Riboflavin (vitamin B2) is the precursor of the flavin coenzymes FMN and FAD, which are essential for oxidative energy metabolism, the electron transport chain, fatty-acid oxidation, and the metabolism of other micronutrients (folate, vitamin B6, niacin, iron). Frank deficiency (ariboflavinosis) causes angular stomatitis, cheilosis, glossitis, sore throat, normocytic anemia and dermatitis, but is rare in developed countries; correcting it resolves these signs. In non-deficient people the best-supported supplementation benefit is high-dose (400 mg/day) migraine prophylaxis in adults, where small RCTs show reduced attack frequency (NNT ~2.3 in Schoenen 1998), though pediatric results are mixed/null. Blood-pressure lowering is real but restricted to a genetic subgroup (MTHFR 677TT hypertensives); there is no evidence routine riboflavin benefits replete adults beyond these uses.

What is the typical dose of Vitamin B2 (Riboflavin)?

Adult RDA (US IOM): 1.3 mg/day (men), 1.1 mg/day (women); 1.4 mg (pregnancy), 1.6 mg (lactation). EFSA sets a similar adult Population Reference Intake of 1.6 mg/day. Typical supplement/B-complex doses 1.7-25 mg/day. Migraine prophylaxis dose used in trials: 400 mg/day. No Tolerable Upper Intake Level (UL) has been established, because no adverse effects from high oral intake have been reliably documented and intestinal absorption is limited above ~27 mg per dose.

Is Vitamin B2 (Riboflavin) safe? Any cautions or side effects?

Very low toxicity; riboflavin is water-soluble and excess is excreted in urine, so no UL is set (IOM/NIH ODS/EFSA). The main visible effect of high doses is bright yellow-orange urine (flavinuria), which is harmless. Photosensitivity is theoretical and not clinically significant from oral intake. Interactions: certain drugs may lower riboflavin status or interact (e.g., anticholinergics and probenecid affecting absorption/excretion; chronic high-dose phenothiazines/tricyclics can impair conversion to coenzymes). Riboflavin is photodegraded—keep supplements away from light. No teratogenic, cardiovascular, or carcinogenic signals are associated with riboflavin, unlike some other vitamins (e.g., beta-carotene in smokers, preformed vitamin A).

How many studies support Vitamin B2 (Riboflavin)?

NutriDex cites 11 sources for Vitamin B2 (Riboflavin), graded "Moderate".

Cite this page
APA

Peh, D. (2026). Vitamin B2 (Riboflavin): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/vitamin-b2

BibTeX
@misc{nutridex_vitamin_b2,
  author       = {Peh, Daryl},
  title        = {Vitamin B2 (Riboflavin): Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/vitamin-b2},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

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