Vitamin B2

Vitamin B2 is the water-soluble vitamin your body uses to turn food into usable energy. Inside cells it becomes two coenzymes called FMN and FAD. These run hundreds of reactions in metabolism. They help release iron from storage. They protect cells from oxidative stress.^[1] Your body cannot store much riboflavin. Excess leaves in urine within hours. Daily intake matters.

If you have heard about B2 for migraines, for energy or alongside iron, this page covers the forms, how much you need and what the research shows.

Forms of vitamin B2

Riboflavin is the parent form. Your body converts it into the two active coenzymes that do the actual work in your cells.^[1]

Riboflavin is the form found in food and in most supplements. It is the form used in nōuxx Cycle Routine across all three phases. It is well absorbed in the small intestine.^[1]

Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are the two active coenzymes. About 90% of dietary riboflavin shows up as FAD. They sit at the centre of energy-yielding reactions in every cell.^[1]

Riboflavin is found in dairy, eggs, lean meat, oily fish, leafy greens, almonds and fortified cereals. Milk is one of the densest sources in a Western diet. Riboflavin is sensitive to light. Milk in clear bottles loses meaningful riboflavin within hours of light exposure.^[1]

Severe riboflavin deficiency is called ariboflavinosis. It shows up as cracked lips, sore throat, inflammation of the tongue, scaly skin around the nose and mouth. Anaemia follows.^[3] Severe deficiency is rare in high-income countries. Sub-clinical deficiency is much more widespread. It is particularly common in women of reproductive age across Europe.^[3]

How much you need

The European Food Safety Authority sets the population reference intake for riboflavin at 1.6 mg per day for adult women. Pregnancy raises that to 1.9 mg. Breastfeeding raises it to 2.0 mg.^[1] nōuxx provides 2 mg per phase. This covers the daily target with a small buffer.

There is no upper limit set for riboflavin. Excess is excreted in urine. High doses turn urine bright yellow. This is harmless. It is the most reliable visual sign a B-complex has been absorbed.^[1]

The science on women's health

Migraine prevention

Migraine affects roughly three times more women than men. The strongest non-deficiency evidence base for riboflavin sits in migraine prophylaxis at high doses of 400 mg per day.^[4]

A 2021 systematic review and meta-analysis of nine trials in 673 patients found that riboflavin at 400 mg per day for three months significantly reduced migraine days, attack duration, attack frequency and pain score.^[4] A 2024 dose-response meta-analysis of 22 randomised trials confirmed that riboflavin reduced attack frequency compared with placebo.^[5] The proposed mechanism is improved mitochondrial energy production in brain cells, which is implicated in migraine pathophysiology.

Be honest about what this means for nōuxx. The 2 mg dose in Cycle Routine sits at nutritional intake level. It is not a migraine treatment dose. Women using high-dose riboflavin for migraine prophylaxis should do so under clinical guidance.

Iron metabolism and anaemia

Riboflavin is required to release iron from its storage protein ferritin so it can be used for red blood cell production.^[6] When riboflavin runs low this step slows down. Iron supplementation works less well.

A 2024 review in the Proceedings of the Nutrition Society drew together the evidence on riboflavin and anaemia in pregnancy. Sub-clinical riboflavin deficiency is common in women of reproductive age in both low- and high-income countries. Randomised trials in pregnant women have shown that riboflavin improves haematological status alongside iron.^[6]

A 2024 narrative review focused on women's health concluded that riboflavin status influences urogenital health, hormonal regulation across the menstrual cycle and pregnancy outcomes.^[7] The biology lines up with why nōuxx Bloody Berry pairs B2 with iron.

EU authorised health claims

Under EU law, riboflavin is officially authorised to carry the following health claims:

• Riboflavin contributes to the reduction of tiredness and fatigue
• Riboflavin contributes to normal energy-yielding metabolism
• Riboflavin contributes to normal functioning of the nervous system
• Riboflavin contributes to the maintenance of normal skin
• Riboflavin contributes to the maintenance of normal mucous membranes
• Riboflavin contributes to the maintenance of normal red blood cells
• Riboflavin contributes to the maintenance of normal vision
• Riboflavin contributes to the normal metabolism of iron
• Riboflavin contributes to the protection of cells from oxidative stress^[2]

References

[1] National Institutes of Health, Office of Dietary Supplements. Riboflavin: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Riboflavin-HealthProfessional

[2] Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, 25 May 2012. eur-lex.europa.eu

[3] McNulty H, Pentieva K, Ward M. Causes and clinical sequelae of riboflavin deficiency. Annual Review of Nutrition 2023;43:101-122. doi.org/10.1146/annurev-nutr-061121-084407

[4] Chen YS, Lee HF, Tsai CH, et al. Effect of vitamin B2 supplementation on migraine prophylaxis: a systematic review and meta-analysis. Nutritional Neuroscience 2022;25(9):1801-1812. doi.org/10.1080/1028415X.2021.1904542

[5] Talandashti MK, Shahinfar H, Delgarm P, Jazayeri S. Effects of selected dietary supplements on migraine prophylaxis: a systematic review and dose-response meta-analysis of randomized controlled trials. Neurological Sciences 2025;46(2):651-670. doi.org/10.1007/s10072-024-07794-0

[6] Duffy B, McNulty H, Ward M, Pentieva K. Anaemia during pregnancy: could riboflavin deficiency be implicated? Proceedings of the Nutrition Society 2026;85(1):74-81. doi.org/10.1017/S0029665124007468

[7] Dricot CEMK, Erreygers I, Cauwenberghs E, et al. Riboflavin for women's health and emerging microbiome strategies. NPJ Biofilms and Microbiomes 2024;10(1):107. doi.org/10.1038/s41522-024-00579-5