Riboflavin (vitamin B2)
A water-soluble B vitamin, bought most often by people who get migraines.
- Headache frequency
- Getting enough
- Blood pressure
- Gut bacteria
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
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On this page
What is riboflavin (vitamin B2)?
Riboflavin, or vitamin B2, is one of the water-soluble B vitamins, and every living cell needs it. The body turns it into two helper molecules, flavin mononucleotide and flavin adenine dinucleotide, which sit inside enzymes and make their chemistry possible. The riboflavin in supplements is made by fermentation, grown by yeasts and bacteria rather than taken out of food, and it has been sold as a human and animal nutritional supplement for decades. Surveys keep reporting intakes below what is needed, even in countries with plenty of riboflavin-rich food, which is part of why a plain B2 tablet still sells.
Why do people take riboflavin (vitamin B2)?
Headache frequency
The thinking. Riboflavin has a following in Britain among people who get migraines, and for many of them it is the only reason they buy a B vitamin at all. The thinking rests on what it does inside mitochondria, the parts of a cell that release energy: riboflavin is needed by the first two links of that chain, and that is the mechanism researchers point to.
What research has found. Pooling nine trials in 673 adults, migraine days, how often attacks came, how long they lasted and how much they hurt all came out lower on 400 mg a day for three months. A review of seventeen studies in children found attacks less frequent in most comparisons, with more mixed results for length and severity. A fair body of trials has looked at this, and most point the same way.
Getting enough
The thinking. Some people buy B2 simply to cover a gap. Surveys keep reporting intakes below what is needed, even in countries with plenty of riboflavin-rich food, and an inherited limit on absorbing and using the vitamin has been reported in roughly one in ten to one in seven people worldwide. Infections, exercise, diet, ageing and pregnancy all shift how much of it the body has to hand.
What research has found. One trial gave male adults up to 1 mg a day on top of their food for six weeks. The level in their blood rose step by step with the dose once the extra passed 0.4 mg, and more began appearing in the urine above 0.6 mg; from those turning points the researchers put the average daily requirement at about 1.4 mg. Few studies have measured this yet, so there is little to go on either way.
Blood pressure
The thinking. Riboflavin is the helper molecule an enzyme called MTHFR needs, and one common version of the gene that makes it goes with higher blood pressure. People who have had that version picked up in a genetic test are the ones who buy riboflavin with blood pressure in mind; the thinking is that a scarce helper leaves a fussy enzyme working less well.
What research has found. A review pooling four trials in 374 adults called the evidence very uncertain: systolic pressure was no different, diastolic came out about 3 mmHg lower, and most trials were judged at high risk of bias. Two smaller trials, in adults already on blood-pressure medicines who carried that version, found systolic readings 6 to 9 mmHg lower on 1.6 mg a day. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.
Gut bacteria
The thinking. A newer reason, and a smaller one. The thinking is that a vitamin can work either directly on the body or indirectly, by changing what the bacteria in the gut do, and riboflavin has been tested for the second. Interest settled on one bacterium in particular, Faecalibacterium prausnitzii, and on butyrate, one of the short-chain fatty acids gut bacteria make.
What research has found. One trial gave healthy volunteers 50 or 100 mg a day for a fortnight. Neither dose on its own changed how much of that bacterium was present, and the fatty-acid profile differed only slightly; when the two dose groups were combined, butyrate production came out higher, and the network of bacteria looked more stable. Very little research has measured this so far, either way.
What does riboflavin (vitamin B2) do in the body?
Riboflavin is a helper, not a fuel. The body converts it into two coenzymes, flavin mononucleotide and flavin adenine dinucleotide, and those sit inside a large family of enzymes called flavoproteins, holding them in shape and letting them do their chemistry. Because so many enzymes depend on them, riboflavin turns up wherever the body is moving energy about, above all in the mitochondria, where the first two complexes of the respiratory chain are flavoproteins.
That one job explains the range. The same coenzymes are needed to turn used glutathione back into its working form, which is why riboflavin is described as part of the body’s own antioxidant housekeeping; in the nervous system it is needed to build myelin, the sheath around nerve fibres. It is also the cofactor for MTHFR, the enzyme that sits in the chemistry handling homocysteine, which is where the gene-variant research comes from. Being water-soluble, what the body cannot hold on to leaves in the urine.
What do people say about taking riboflavin (vitamin B2)?
These are anecdotes people have shared, not evidence.
What people like
- Every thread read was about headaches. Nobody described taking riboflavin for anything else, and many came to it through a GP or a neurologist.
- Where people did report a change it was fewer attacks, not none: one described about half as many, another said they lessened over months.
- Several like that it needs no prescription, and one reason it comes up is that people are trying to replace or avoid prescribed medicines.
- In several threads it is one poster passing it to another, citing a specialist’s advice or national guidance rather than a result of their own.
Common complaints
- The commonest report is that it did nothing. In both of the longer threads, more people said it made no difference than said it helped.
- Several gave it six months before stopping, and more than one wondered afterwards whether an early improvement had really been the supplement.
- One poster warns that it turns your urine a funny colour, and says plainly that this is harmless rather than a reason to stop.
- Finding the strength the threads name is a grumble: one poster could get only 100 mg tablets on the high street and ordered online instead.
- People muddle it with the other B vitamins; one was taking a general B supplement at a small fraction of the dose the threads name.
How people take it
- 400 mg a day is the figure the threads keep returning to, and posters correct each other whenever a smaller strength is mentioned.
- One splits it as 200 mg twice a day, another takes 200 mg once, and one was started on 500 mg by a GP.
- Three months is the trial period people give it, usually on a specialist’s advice; several say nothing had changed at four weeks or ten days.
- It is rarely taken alone: magnesium appears alongside it in nearly every account, and coenzyme Q10 or feverfew in a few of them.
Read from these public discussions:
- Riboflavin - anyone tried it? (Patient.info, 2018)
- Vitamin B2 and migraine prevention (Patient.info, 2018)
- Candesartan and migraine (Mumsnet, 2024)
- Help me with my migraines (Mumsnet, 2018)
- Migraines/headaches (Mumsnet, 2020)
- Help for migraine (Mumsnet, 2025)
What forms of riboflavin (vitamin B2) are there?
| Form | What’s different | Per serving, on products we list |
|---|---|---|
| Riboflavin | Riboflavin as it is, the form the body converts into its two working helper molecules. | 50 mg |
| Riboflavin-5-phosphate | Riboflavin with a phosphate group already attached, a step the body otherwise carries out itself. | not in our price tables yet |
What else is worth knowing about riboflavin (vitamin B2)?
- Riboflavin turns urine a vivid yellow, which is the vitamin itself leaving the body. One trial used that on purpose, giving 400 mg the night before an operation so a surgeon could see the urine arriving, and found the colour clearly stronger than after a dummy capsule.
- Labels give the riboflavin per serving, and a serving may be more than one tablet; it is sold either as plain riboflavin or as riboflavin-5-phosphate.
- The amounts in these studies cover an enormous range: 1.6 mg a day in the blood-pressure trials, and 400 mg a day for three months in the pooled migraine trials.
- Where side effects were reported they were few: the blood-pressure review found a single trial that listed them by group, two on riboflavin and one on placebo, and the review of children’s studies reported no negative outcomes and few side effects across five studies.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (13 studies)
- Systematic Review Suggests Nutraceuticals Containing Vitamin B2 Could Provide an Alternative Treatment for Paediatric Migraines. (2025, systematic review)
- Effect of Vitamin B2 supplementation on migraine prophylaxis: a systematic review and meta-analysis. (2022, meta-analysis)
- Plasma riboflavin is a useful marker for studying riboflavin requirement in Chinese male adults. (2016, randomised trial)
- Riboflavin supplements for blood pressure lowering in adults. (2025, meta-analysis)
- Blood pressure in treated hypertensive individuals with the MTHFR 677TT genotype is responsive to intervention with riboflavin: findings of a targeted randomized trial. (2013, randomised trial)
- Riboflavin offers a targeted strategy for managing hypertension in patients with the MTHFR 677TT genotype: a 4-y follow-up. (2012, randomised trial)
- Riboflavin Supplementation Promotes Butyrate Production in the Absence of Gross Compositional Changes in the Gut Microbiota. (2023, randomised trial)
- Riboflavin: The Health Benefits of a Forgotten Natural Vitamin. (2020, review)
- Riboflavin and health: A review of recent human research. (2017, review)
- Production of Vitamin B2 (Riboflavin) by Microorganisms: An Overview. (2020, review)
- Riboflavin Deficiency-Implications for General Human Health and Inborn Errors of Metabolism. (2020, review)
- Riboflavin in Neurological Diseases: A Narrative Review. (2021, review)
- An update on the genetics, clinical presentation, and pathomechanisms of human riboflavin transporter deficiency. (2019, review)
How much does riboflavin (vitamin B2) cost?
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