Riboflavin (Vitamin B2)
What it does
Riboflavin, also called vitamin B2, helps the body use energy from food and keeps several enzyme systems working. It is needed to form FAD and FMN, two coenzymes involved in energy metabolism, antioxidant recycling, and the metabolism of other nutrients. Most people get enough riboflavin from dairy, enriched grains, meat, eggs, almonds, mushrooms, and greens, but intake can drop when dairy, fortified foods, or overall food variety are low.
Riboflavin intake is often covered by dairy, enriched grains, meat, eggs, almonds, mushrooms, and leafy greens. The recommended intake is 1.1 mg for women and 1.3 mg for men, and the ideal range shown here is 1.1 to 3.0 mg. No tolerable upper limit has been established, but riboflavin can become easier to miss when dairy, enriched grains, or overall food variety are low.
Energy metabolism. Riboflavin is used to make FAD and FMN, coenzymes that help the body process carbohydrates, fats, and proteins for energy.
Antioxidant recycling. Riboflavin helps support the glutathione recycling system, which is one of the body’s normal antioxidant defenses.
Nutrient activation. Riboflavin is involved in vitamin B6 metabolism, niacin production from tryptophan, iron metabolism, and folate-related pathways.
Folate and MTHFR context. Riboflavin is the source of FAD, a cofactor used by the MTHFR enzyme. That makes B2 relevant to folate metabolism, but it should not turn the page into an MTHFR page.
Why riboflavin can be inconsistent
Riboflavin is not rare, but it depends heavily on a few common food patterns. Dairy and enriched grains cover a lot of intake for many people. If those foods are removed, replacement foods matter.
Dairy often carries a lot of the baseline. Milk and yogurt are common riboflavin sources. People who avoid dairy can still cover riboflavin, but they need other reliable sources such as fortified foods, eggs, meat, almonds, mushrooms, spinach, or enriched grains.
Fortified and enriched foods matter. Riboflavin is added to many enriched grain products and some fortified foods. Diets that remove both dairy and enriched grains need more planning.
Light can degrade riboflavin. Riboflavin is sensitive to light, which is one reason milk is usually sold in opaque containers rather than clear glass.
Pregnancy, lactation, alcohol, and low food intake can change the picture. Riboflavin status can matter more when needs rise, intake drops, or absorption and metabolism are affected by chronic heavy alcohol use, certain medications, or medical context.
Who may need to pay closer attention
Some people are more likely to have low riboflavin intake or higher riboflavin needs than others:
- people who avoid dairy and do not replace it with riboflavin-rich foods
- people who avoid enriched grains and fortified foods
- people eating very low-variety diets
- people who are pregnant or lactating
- people with chronic heavy alcohol use
- people with low food intake or restrictive eating patterns
- people with frequent migraines who are discussing riboflavin with a clinician
None of these factors proves a riboflavin problem. They are reasons to check whether riboflavin-rich foods are in the routine, or talk with a doctor or dietitian about whether testing or supplementation makes sense.
Best food sources
Dairy, enriched grains, meat, eggs, almonds, mushrooms, and leafy greens all provide riboflavin.
| Food | Riboflavin per serving |
|---|---|
| Beef liver, cooked (3 oz) | ~2.9 mg |
| Fortified breakfast cereal (1 serving) | varies widely |
| Milk, 2% (1 cup) | ~0.5 mg |
| Yogurt, plain (1 cup) | ~0.6 mg |
| Beef, cooked (3 oz) | ~0.2-0.3 mg |
| Egg, cooked (1 large) | ~0.2 mg |
| Almonds (1 oz) | ~0.3 mg |
| Portobello mushrooms, grilled (1/2 cup) | ~0.3 mg |
| Spinach, cooked (1/2 cup) | ~0.2 mg |
The dairy and fortified-food pattern. Riboflavin is easy to cover when milk, yogurt, enriched grains, eggs, meat, almonds, mushrooms, or greens are part of the routine. It becomes easier to miss when dairy and enriched foods are both removed without reliable replacements.
How much do you need?
Standard RDA
1.3 mg per day for adult men and 1.1 mg per day for adult women. Pregnancy raises the recommendation to 1.4 mg, and lactation raises it to 1.6 mg.
Individual context matters
Most people cover riboflavin with a varied diet. People avoiding dairy, enriched grains, and fortified foods may need to be more deliberate. Pregnancy, lactation, low food intake, chronic heavy alcohol use, and very high activity levels can also make riboflavin status more relevant.
No established upper limit
No tolerable upper limit has been established for riboflavin. Higher intakes are generally excreted, and bright yellow urine after a B-vitamin supplement is a common riboflavin effect. That does not mean high doses are automatically useful for everyday coverage.
Forms and supplements
Riboflavin supplements are usually straightforward. The main question is whether someone needs extra B2 because of diet pattern, medical context, or clinician guidance.
Riboflavin
The standard form used in many supplements and fortified foods. It is common, effective for basic coverage, and well understood.
Riboflavin-5-phosphate
A coenzyme form used in some supplements. It may make sense in certain formulas, but standard riboflavin is still effective for basic coverage, so R5P should not be presented as automatically better for everyone.
High-dose riboflavin
High-dose riboflavin, often around 400 mg per day, has been studied for migraine prevention. This is a targeted clinical use, not the same as everyday riboflavin coverage.
Nutrient context
Vitamin B6
Riboflavin is involved in converting vitamin B6 into its active form. This is one reason B vitamins are connected, even though each has a different job.
Folate
Riboflavin provides FAD, a cofactor used by the MTHFR enzyme in folate metabolism. This makes riboflavin relevant to folate status without making it a replacement for folate.
Iron
Riboflavin status can affect iron metabolism. This matters most when iron status questions are already part of the picture.
Closing the gap
Riboflavin is usually easy to cover when dairy, enriched grains, eggs, meat, almonds, mushrooms, or greens are part of the routine. The gap shows up when those common sources disappear and nothing replaces them.
The useful check is where B2 is coming from. If dairy or enriched grains are in the routine, intake often looks solid. If they are not, foods like eggs, meat, almonds, mushrooms, greens, fortified foods, or organ meats need to carry more of the load. High-dose riboflavin is mostly relevant for specific uses, such as clinician-guided migraine prevention, not ordinary daily coverage.
See how riboflavin shows up in your usual diet →
The information on this page is educational and does not constitute medical advice. Talk to a qualified healthcare provider before making changes to your diet or interpreting lab results.
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