Riboflavin: a milk and egg vitamin, and what the migraine trials really show

Riboflavin deficiency is rare in wealthy countries and concentrated in two groups: vegans and people who drink little or no milk. The vitamin is also sold in large doses for migraine, and that part of the story splits by age, because what worked in adults kept failing in children.

What it does in the body

• Riboflavin coenzymes play major roles in energy production, cellular function, growth and development, and metabolism of fats, drugs and steroids. — general adults Evidence E source

How much you need

• The RDA for riboflavin is 1.3 mg a day for adult men and 1.1 mg for adult women aged 19 to 50. — general adults Evidence E source
• Most of the riboflavin in food arrives bound up as FAD. Eggs and milk are the exception, carrying it in the free form. And in the American diet it is milk and bread, not liver, that actually delivers it. — general population, US food supply Evidence E source
• In Northern Europe riboflavin comes mostly from milk and meat, which puts vegans in question - except that the surveys disagree with each other about whether vegans actually fall short. — adults in the Nordic and Baltic countries; vegetarians and vegans specifically Evidence E source

How well your body absorbs it

• Riboflavin is the vitamin that light destroys. It breaks down in ordinary daylight, faster as the food gets warmer or less acidic - which is why milk in a clear bottle is not the same food as milk in a carton. — не застосовується: хімія вітаміну Evidence E source
• Boiling costs about twice as much riboflavin as steaming or microwaving the same food, because the vitamin leaves in the water rather than being destroyed by the heat. — general population Evidence E source
• The body takes up almost all the riboflavin in a meal - and then stops: past about 27 mg in one sitting, extra riboflavin simply is not absorbed. — general population Evidence E source
• Riboflavin from whole food is absorbed better than riboflavin taken on its own - 60 to 70 per cent against 50 to 60 per cent. — загальна доросла популяція Evidence E source
• Gut bacteria make riboflavin in the large intestine, and nobody knows whether any of it ever reaches us. — не застосовується Evidence E source

What too little does

• Riboflavin deficiency cracks the corners of the mouth and lips, inflames the tongue and throat, and in severe cases damages the liver and nerves. — people with riboflavin deficiency Evidence E source
• For a handful of people born without working riboflavin transporters, high-dose riboflavin is not a supplement but a life-saving drug - and it works best started early. — patients with riboflavin transporter deficiency caused by SLC52A3 or SLC52A2 mutations, formerly called Brown-Vialetto-Van Laere or Fazio-Londe syndrome Evidence E source
• There is no blood test that tells you whether you have enough riboflavin: no cut-off has ever been agreed for the plasma forms, and the functional test does not work at all in people with G6PD deficiency. — general population; specifically named limitation in people with G6PD deficiency Evidence E source

Who is most likely to fall short

• Vegetarian athletes are at risk of riboflavin deficiency, because their need is higher and some vegetarians exclude all animal products. — general adults Evidence E source
• Vegans and people who drink little milk are the groups most likely to fall short on riboflavin in wealthy countries. — vegans and low-milk consumers Evidence E source
• The gene variant that makes riboflavin matter more is not rare: it affects 5 to 15 per cent of most populations, about a fifth in parts of Italy and China, and nearly a third in Mexico. — general populations worldwide Evidence E source

What the evidence does and does not show

• In two small randomised studies in children, 50 to 200 mg of riboflavin a day did not reduce migraine frequency or severity. — children with migraine, two small randomised studies Evidence B source
• Across 22 randomised trials of supplements for migraine, riboflavin cut the number of attacks by about one and a third a month. — adults and children with migraine, 22 trials of dietary supplements Evidence A source
• An earlier review of 11 riboflavin trials found the effect holds up in adults but not reliably in children and teenagers. — adults, children and adolescents with migraine across 11 trials Evidence A source
• Cochrane looked for the blood-pressure effect of riboflavin in 2025 and could not find one it would stand behind: four small trials, most of them at high risk of bias, and a systolic result whose confidence interval still contains zero. — adults, with or without antihypertensive treatment, taking oral riboflavin alone against placebo or no additional treatment Evidence A source
• Riboflavin does cut migraine attacks - by a bit over one a month - and in the same pooled comparison magnesium and CoQ10 cut more. — adults and children with migraine taking dietary supplements for prophylaxis Evidence A source
• The widely repeated claim that riboflavin drops blood pressure by 6 to 13 mmHg in people with one gene variant comes from three trials - and it is exactly these that Cochrane later judged too weak to rely on. — patients homozygous for the MTHFR 677TT genotype Evidence E source
• No food or supplement sold in the United States may legally claim that riboflavin prevents or treats anything. FDA has authorised no health claim for it at all. — усі харчові продукти й добавки на ринку США Evidence E source

What too much does

• No Tolerable Upper Intake Level was set for riboflavin, because adverse effects from high intakes have not been reported. — general adults Evidence E source
• There is no upper limit for riboflavin, and the honest reason is not that safety was established but that nobody has looked properly. The high-dose studies asked people how they felt and measured nothing. — adults taking 100-400 mg/day of supplemental riboflavin in the reviewed studies Evidence E source
• You cannot overdose on riboflavin from food or from a tablet: the gut stops absorbing it somewhere around 25 to 30 mg and the rest leaves in the urine. — adults Evidence E source

Medicines it interacts with

• The NIH states riboflavin has no known clinically relevant interactions with medications. Evidence E source
• Riboflavin does interact with medicines after all: the blood thinner ticagrelor raises riboflavin in the blood by about a fifth, because the two share a transporter in the gut wall. — healthy volunteers; the exact number randomised is not stated in the abstract and the full text was not retrievable Evidence B source

What to do with this

Milk, yogurt, eggs, meat and fortified cereal carry most of the riboflavin in an ordinary diet. If those are on your plate regularly, this page is background reading.

Two groups should look twice. Vegans, and anyone who has dropped dairy without deliberately replacing it, are the people most likely to fall short in a wealthy country. Vegetarian athletes are named as a separate risk group, because training raises the requirement. Almonds, mushrooms, fortified plant drinks and nutritional yeast are the practical replacements.

If you are taking riboflavin for migraine, the evidence is better than it looks from the usual shrug. Pooling 22 randomised trials, riboflavin cut attacks by about one and a third a month, which is real but modest, and the trials that carried that result were in adults. In children two small randomised studies found no reduction in either the number of headaches or their severity, so the same bottle is a fair try for a grown-up and a poor bet for a ten-year-old.

The blood pressure claim, and what happened to it

If you have read that riboflavin lowers blood pressure dramatically in people carrying a particular gene variant, that claim is real, it is specific, and it has now been reviewed.

The variant is MTHFR 677TT, and it is not rare. It affects 5 to 15 per cent of most populations, around 20 per cent in parts of Italy and China, and about 30 per cent in Mexico. The biology is tidy: that version of the enzyme holds on less well to its FAD cofactor, and FAD is made from riboflavin. Three trials reported blood pressure falling by 6 to 13 mmHg in people with the TT genotype after 16 weeks of riboflavin.

Unsettled. Cochrane went looking for that effect in 2025 and would not stand behind it. Four small trials, most at high risk of bias. Systolic pressure came out at a mean difference of -1.94 mmHg, with a confidence interval running from -5.74 to 1.86, which includes no effect at all. Diastolic came out at -3.03 with an interval from -5.97 to -0.09, technically clear of zero and rated very low certainty. The three trials that produced the headline figure are the same body of work Cochrane judged too weak to rely on. So the mechanism is plausible, the early results were striking, and the pooled answer is that nobody knows. If you carry that variant, this is worth watching and is not yet worth treating.

Established. The migraine result is on firmer ground and is smaller than the marketing. Riboflavin cut attacks by about 1.34 a month. In the same pooled comparison magnesium cut 2.51 attacks, along with severity and monthly migraine days, and CoQ10 cut 1.73 attacks plus severity and duration. Riboflavin works and came third.

Why there is no upper limit, and why that is not reassurance

Unsettled. No upper limit has been set for riboflavin, and the honest reason is not that its safety was established. No adverse effects have been reported from food or supplements, but the studies that used 100 to 400 mg a day asked people how they felt and measured no objective biochemistry at all. The data are described as insufficient to set a limit. The practical reassurance is different and better: absorption in the small intestine saturates around 25 to 30 mg, so past roughly 27 mg in one dose the extra riboflavin is simply not taken up, and what does get in leaves in urine. A large tablet mostly makes expensive yellow urine.

That ceiling has a second use. Riboflavin from whole food is absorbed at 60 to 70 per cent, against 50 to 60 per cent for free riboflavin taken on its own at ordinary doses. The food does better than the tablet.

Light, water, and what that means in a kitchen

Riboflavin is the vitamin that daylight destroys. It breaks down in ordinary visible light, faster as food gets warmer or less acidic, which is a real difference between milk sold in a clear bottle and the same milk in a carton. It is most stable in the dark at a pH of 3.5 to 4.

Water matters too, in a way that has a fix. Boiling costs roughly twice as much riboflavin as steaming or microwaving the same food, because the vitamin leaves into the water rather than being destroyed by heat. Steam it, microwave it, or use the cooking water.

Most of the riboflavin in food arrives bound up as FAD. Eggs and milk are the exception and carry the free form. And in the American diet the biggest actual contributors are not the richest foods. Liver tops any table of concentration, and what delivers riboflavin to real people is milk and milk drinks, bread and bread products, meat-based mixed dishes and ready-to-eat cereal.

Unsettled. There is no blood test that will tell you whether your riboflavin is adequate. No cut-off values have ever been proposed for plasma riboflavin, FAD or FMN, because they track what you ate recently rather than your status. The functional test, EGRAC, does not work in people with G6PD deficiency, because that enzyme holds FAD too tightly to reveal a shortage. So if you suspect low riboflavin, what settles it is the distinctive picture of cracked mouth corners and a sore tongue plus a response to treatment, rather than a number.

Unsettled. Whether vegans fall short is genuinely open. In Northern Europe riboflavin comes mostly from milk and meat, and intake runs 1.8 to 2.3 mg per 10 MJ in the Nordic countries against 1.4 to 1.7 in the Baltic ones. One body of survey work reports that vegan diets may not supply enough. Another reports intake similar between vegans and omnivores. Since there is no agreed blood test to settle it, the sensible move for anyone eating no dairy is to build in almonds, mushrooms, fortified plant drinks and nutritional yeast and stop worrying about the argument.

One more open question, for interest rather than for action. Bacteria in the large intestine make flavins, and the cells lining the colon use them. Whether any of that ever reaches the rest of you is unknown.

Not for everyone. There is a small group for whom riboflavin is a drug rather than a nutrient. People born without working riboflavin transporters cannot absorb or move the vitamin properly, and they develop hearing loss, bulbar palsy and breathing difficulty. High-dose riboflavin can be life-saving there, and it works best when started soon after symptoms appear. That is a diagnosis made by a specialist, and it is the reason a neurologist may prescribe doses this page would otherwise call pointless.

Established. Riboflavin does have one proper drug interaction after all. The blood thinner ticagrelor raised peak plasma riboflavin by about a fifth, because the two share transporters in the gut wall, BCRP and MRP4, which ticagrelor blocks. The direction is worth noting. The drug pushes riboflavin up rather than down, so this is a curiosity about how the gut works rather than a reason to supplement.

What a riboflavin label is allowed to say

Established. No food or supplement sold in the United States may legally claim that riboflavin prevents or treats anything. A health claim is unlawful unless the regulations specifically provide for it, and the sections that do run without gaps from 101.72 to 101.83. They cover calcium and vitamin D, dietary lipids, sodium, saturated fat, fibre, fruits and vegetables, folate, sugar alcohols, soluble fibre, soy protein and plant sterols. Riboflavin is not among them, and no qualified claim exists for it either.

Hold that next to the two claims further up this page and it fits them rather than contradicting them. An empty register is a fact about the regulator, not about the vitamin. It records that the evidence never reached the bar an authorised claim demands, which is exactly what the migraine result and the blood pressure result look like from the outside. Riboflavin does reduce migraine attacks by about 1.34 a month. That is a real finding and it is also not the kind of finding a regulator will let a cereal box advertise. The absence on the label is about the strength of the evidence rather than about whether anything is happening.

Where to get it from food

The bottom line

Men need 1.3 mg a day and women 1.1 mg, and no upper limit was set because high intakes have not produced harm. Milk, eggs, meat and fortified grain carry most of it, which is why avoiding dairy without replacing it is the main route to falling short. The deficiency has a distinctive look, with cracks at the corners of the mouth and a swollen tongue. On migraine the trials split by age. A 2025 meta-analysis of 22 supplement trials found riboflavin cut attacks by about one and a third a month, and an earlier review of 11 trials found a consistent effect in adults and a mixed one in children. Two small randomised studies in children found that 50 to 200 mg a day did not reduce either the number of headaches or their severity. Three corrections belong on this page. The missing upper limit does not mean riboflavin has been shown to be safe at any dose. It means nobody has looked properly: the 100 to 400 mg studies asked people how they felt and measured no biochemistry. The blood pressure claim that circulates about riboflavin, 6 to 13 mmHg in people with one gene variant, rests on three trials, and a 2025 Cochrane review of that question found a systolic result whose confidence interval still contains zero. And there is no blood test that tells you whether your riboflavin is adequate, because no cut-off has ever been agreed.

Sources

1. rib-01 · Position of an expert body · expert body statement
   These coenzymes play major roles in energy production; cellular function, growth, and development; and metabolism of fats, drugs, and steroids.
   NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
2. rib-02 · Position of an expert body · expert body statement
   1.3 mg for adult males and 1.1 mg for adult females ages 19–50 (value from the source's table, not a sentence)
   NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
3. rib-c-02 · Position of an expert body · agency fact sheet
   The riboflavin in most foods is in the form of FAD, although the main form in eggs and milk is free riboflavin [9].
   Riboflavin, Fact Sheet for Health Professionals, NIH Office of Dietary Supplements · checked 2026-09-21 · independently re-checked
4. rib-c-14 · Position of an expert body · scoping review of national dietary surveys
   Major sources of riboflavin in the Nordic diets are milk and dairy products, meat, and meat products. The average dietary intake according to national dietary surveys is in the range of 1.8 mg–2.3 mg/10 MJ in the Nordic countries and 1.4–1.7 mg/10 MJ in the Baltic countries
   Nordic Nutrition Recommendations 2023 scoping review, Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
5. rib-c-01 · Position of an expert body · scoping review
   Riboflavin, despite being a water-soluble vitamin, is sparingly soluble in water (10–13 mg/100 mL). It is also a very light-sensitive vitamin, degrading even in visible light, increasingly with pH and temperature.
   Nordic Nutrition Recommendations 2023 scoping review, Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
6. rib-c-03 · Position of an expert body · agency fact sheet
   Because riboflavin is soluble in water, about twice as much riboflavin content is lost in cooking water when foods are boiled as when they are prepared in other ways, such as by steaming or microwaving [11].
   Riboflavin, Fact Sheet for Health Professionals, NIH Office of Dietary Supplements · checked 2026-09-21 · independently re-checked
7. rib-c-04 · Position of an expert body · agency fact sheet
   About 95% of riboflavin in the form of FAD or FMN from food is bioavailable up to a maximum of about 27 mg of riboflavin per meal or dose [3].
   Riboflavin, Fact Sheet for Health Professionals, NIH Office of Dietary Supplements · checked 2026-09-21 · independently re-checked
8. rib-c-05 · Position of an expert body · scoping review
   This mechanism is saturated at doses of about 30–50 mg. Absorption rates of free riboflavin are reported to be 50–60% at doses of 2–25 mg, and absorption rates of riboflavin from whole foods are 60–70% (13, 14).
   Nordic Nutrition Recommendations 2023 scoping review, Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
9. rib-c-16 · Position of an expert body · scoping review
   In the large intestine, bacteria produce flavins utilized by colonic epithelial cells. However, it is unknown if microbial flavins are available as a source for riboflavin metabolism (21).
   Nordic Nutrition Recommendations 2023 scoping review, Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
10. rib-05 · Position of an expert body · expert body statement
    The signs and symptoms of riboflavin deficiency (also known as ariboflavinosis) include skin disorders, hyperemia (excess blood) and edema of the mouth and throat, angular stomatitis (lesions at the corners of the mouth), cheilosis (swollen, cracked lips), hair loss, reproductive problems, sore throat, itchy and red eyes, and degeneration of the liver and nervous system
    NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
11. rib-c-13 · Position of an expert body · agency fact sheet
    Although no cure exists for riboflavin transporter deficiency, high-dose riboflavin supplementation can be a life-saving treatment in this population, especially when it is initiated soon after symptom onset.
    Riboflavin, Fact Sheet for Health Professionals, NIH Office of Dietary Supplements · checked 2026-09-21 · independently re-checked
12. rib-c-15 · Position of an expert body · scoping review
    No cut-off values have been suggested for plasma concentrations of riboflavin, FAD, and FMN, for the assessment of riboflavin deficiency or adequacy (1)...One limitation of EGRAC is that it cannot be used in individuals with glucose-6-phosphate dehydrogenase (G6PD)-deficiency, as their EGR have an increased avidity for FAD, which prevents the detection of low riboflavin status.
    Nordic Nutrition Recommendations 2023 scoping review, Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
13. rib-04 · Position of an expert body · expert body statement
    Vegetarian athletes are at risk of riboflavin deficiency because of their increased need for this nutrient and because some vegetarians exclude all animal products.
    NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
14. rib-06 · Position of an expert body · expert body statement
    Vegans and those who consume little milk in developed countries are also at risk of riboflavin inadequacy
    NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
15. rib-c-12 · Position of an expert body · Cochrane systematic review (background)
    Though the prevalence of the TT genotype has not been estimated for every population, it typically varies from 5% to 15%, and may be around 20% in areas in Italy and China and 30% in Mexico [13].
    Cochrane Database of Systematic Reviews, 2025 (CD015464.pub2) · checked 2026-09-21 · independently re-checked
16. rib-08 · Randomised controlled trial(s) · review of trials cited by expert body
    However, two small randomized studies in children found that 50 to 200 mg/day riboflavin did not reduce the number of migraine headaches or headache severity compared to placebo
    NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
17. rib-t1 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis
    Riboflavin decreased attack frequency (MD = -1.34).
    Hosseini et al., Neurological Sciences, 2025 · checked 2026-09-16 · independently re-checked
18. rib-t2 · Meta-analysis or systematic review · systematic review of clinical trials
    A total of 11 clinical trials reveal a mixed effect of riboflavin in the prophylaxis of migraine headache. Five clinical trials show a consistent positive therapeutic effect in adults; four clinical trials show a mixed effect in paediatric and adolescent patients, and two clinical trials of combination therapy have not shown benefit.
    Thompson and Saluja, Journal of Clinical Pharmacy and Therapeutics, 2017 · checked 2026-09-16 · independently re-checked
19. rib-c-06 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis
    The evidence is very uncertain about the effect of riboflavin on systolic blood pressure (MD -1.94 mmHg, 95% CI -5.74 to 1.86 mmHg; P = 0.32; 3 studies, 320 participants; very low-certainty evidence) and diastolic blood pressure (MD -3.03 mmHg, 95% CI -5.97 to -0.09 mmHg; P = 0.04; 2 studies, 271 participants; very low-certainty evidence).
    Cochrane Database of Systematic Reviews, 2025 (CD015464.pub2) · checked 2026-09-21 · independently re-checked
20. rib-c-07 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    Magnesium supplementation reduced migraine attacks (mean difference (MD) = -2.51), severity (MD = -0.88), and the monthly migraine days (MD = -1.66) compared with the control group. CoQ10 decreased the frequency (MD = -1.73), severity (MD = -1.35), and duration of migraine (MD = -1.72). Riboflavin decreased attack frequency (MD = -1.34).
    Neurological Sciences, 2025 · checked 2026-09-21 · independently re-checked
21. rib-c-11 · Position of an expert body · scoping review
    Three clinical trials of riboflavin supplementation have demonstrated a substantial blood pressure reduction of 6–13 mmHg among patients with the MTHFR 677TT (homozygous) genotype when receiving riboflavin supplements for 16 weeks (32–34).
    Nordic Nutrition Recommendations 2023 scoping review, Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
22. rib-c-17 · Position of an expert body · federal regulation
    No expressed or implied health claim may be made on the label or in labeling for a food, regardless of whether the food is in conventional food form or dietary supplement form, unless:
    21 CFR 101.14, Health claims: general requirements, пункт (e) Prohibited health claims · checked 2026-09-21 · independently re-checked
23. rib-03 · Position of an expert body · expert body statement
    Because adverse effects from high riboflavin intakes from foods or supplements (400 mg/day for at least 3 months) have not been reported, the FNB did not establish ULs for riboflavin.
    NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
24. rib-c-08 · Position of an expert body · scoping review
    There are no reports of adverse effects of high riboflavin intakes from dietary sources or supplements (1). The limited studies in which large doses (100–400 mg/day) of supplemental riboflavin have been administered do not indicate any adverse effects (31). However, these studies only included self-reported assessment of adverse effects and no objective biochemical markers. Hence, there are insufficient data to set a UL for riboflavin.
    Nordic Nutrition Recommendations 2023 scoping review, Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
25. rib-c-10 · Position of an expert body · Cochrane systematic review (background)
    Riboflavin toxicity is not a concern, as absorption in the small intestine is saturated at about 25 mg to 30 mg, and excess riboflavin is excreted primarily in the urine [6, 7].
    Cochrane Database of Systematic Reviews, 2025 (CD015464.pub2) · checked 2026-09-21 · independently re-checked
26. rib-07 · Position of an expert body · expert body statement
    Riboflavin is not known to have any clinically relevant interactions with medications.
    NIH Office of Dietary Supplements, Riboflavin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
27. rib-c-09 · Randomised controlled trial(s) · randomised crossover pharmacokinetic trial
    Intake of 90 mg ticagrelor increased the ratio between the peak plasma riboflavin concentration and the fasting riboflavin concentration before ticagrelor administration by 1.20-fold (90% confidence interval, 1.10-1.32; P = 0.006) compared to placebo.
    Clinical Pharmacology & Therapeutics, 2024 · checked 2026-09-21 · independently re-checked