Vitamin B2 (Riboflavin)
Riboflavin, B2 · Riboflavin
Riboflavin is a water-soluble B vitamin that forms coenzymes essential for energy metabolism and cellular oxidation-reduction reactions.
Medically reviewed by Rayna Dvorak, ND, LAc
At a glance
| What it is | Water-soluble B vitamin forming FAD and FMN |
| Where it’s from | Dairy, eggs, meat, greens, fortified grains |
| Main roles | Energy metabolism, redox reactions, other B-vitamin activation |
| Common forms | Riboflavin, riboflavin-5-phosphate |
| Key caution | Low toxicity; harmless bright-yellow urine |
| Individualized guidance | Discuss needs with a qualified clinician |
What it is
A water-soluble B vitamin that the body converts into the flavin coenzymes FAD and FMN. These are essential for many energy-producing and oxidation-reduction reactions and for activating other nutrients like B6 and folate.
How it works in the body
Riboflavin-derived FAD and FMN act as electron carriers in the metabolism of carbohydrates, fats, and proteins and in the mitochondrial electron transport chain. They also support glutathione recycling and the metabolism of other B vitamins. Some proposed roles beyond these core functions remain theoretical.
What it’s commonly studied or used for
Evidence varies by use. Ratings describe the strength of human research, not a promise of benefit for any individual.
| Area | What the evidence suggests | Evidence |
|---|---|---|
| Deficiency correction | Repletion studied for riboflavin deficiency. | Stronger |
| Energy metabolism support | Core coenzyme role in producing cellular energy. | Stronger |
| Migraine frequency | Studied as a preventive; some supportive evidence. | Moderate |
| Supporting other B-vitamin activity | Needed to activate B6 and metabolize folate. | Moderate |
| Skin and mucosa | Involved in normal skin and mucosal health. | Preliminary |
Signs of possible insufficiency
Deficiency risk rises with low dairy and meat intake, alcohol use, and some inherited metabolic conditions, and often coexists with other B-vitamin shortfalls. It may show as mouth and skin changes. Testing is not routine in healthy people.
Food and natural sources
Milk and dairy, eggs, lean meats, organ meats, almonds, mushrooms, leafy greens, and fortified or enriched grains. Riboflavin is degraded by light exposure.
Available forms
| Form | General notes | Consideration |
|---|---|---|
| Riboflavin | Standard form found in most supplements. | — |
| Riboflavin-5-phosphate | Preformed active coenzyme form. | No proven superiority for most people. |
| B-complex blends | Provides riboflavin with other B vitamins. | Check total amounts across products. |
Typical use & dosing context
Requirements vary by age, sex, and pregnancy or lactation and are small daily amounts; riboflavin is water-soluble with no established tolerable upper limit. Treat any numbers as context only. Individualized guidance from a qualified clinician is recommended.
Safety, side effects & who should use caution
- Very well tolerated with low toxicity due to water solubility.
- Commonly turns urine bright yellow, which is harmless.
- Considered compatible with pregnancy and breastfeeding at dietary levels.
- High doses rarely cause mild digestive upset in some people.
- No established upper intake limit has been set.
- People with malabsorption or alcohol use may need extra attention.
- Seek care for persistent mouth, eye, or skin symptoms rather than self-treating.
“Natural” does not mean risk-free. Amounts safe for one person can be inappropriate for another.
Medication & supplement interactions
| Interacts with | Nature of the interaction |
|---|---|
| Certain antidepressants and antipsychotics | May affect riboflavin metabolism; usually minor. |
| Alcohol | Impairs absorption and increases requirements. |
| Anticholinergic drugs | May slow gut transit and alter absorption theoretically. |
| Tetracycline antibiotics | Taking together may affect each other’s absorption; separate timing. |
Quality & product selection
Choose brands with third-party testing, opaque or protective packaging since riboflavin is light-sensitive, and clear labeling of form and dose. Be cautious of exaggerated energy claims.
Find practitioner-grade Vitamin B2 (Riboflavin) in Dr. Rayna’s Fullscript dispensary →
Explore practitioner-selected options
Where appropriate, Dr. Rayna may maintain practitioner-curated products or public wellness protocols through Fullscript. Inclusion of a product does not mean it is right for you.
Unsure whether Vitamin B2 (Riboflavin) fits your health history?
Supplement plans are most useful when they reflect your medications, labs, symptoms, and goals.
Common questions
Bright-yellow urine is a normal, harmless effect of excess riboflavin being excreted and is not a cause for concern.
Some studies suggest riboflavin may support reduced migraine frequency for certain people, but results vary; discuss it with your clinician.
Diets including dairy, eggs, meat, greens, and fortified grains typically provide adequate riboflavin for most people.
Riboflavin-5-phosphate is the active form, but standard riboflavin is well absorbed and adequate for most people.
Related supplements & topics
References
- NIH Office of Dietary Supplements
- Natural Medicines database
Educational only. This profile is general information, not medical advice, and does not create a provider–patient relationship. Do not start, stop, or change any medication or supplement based on this page without guidance from a licensed clinician. For emergencies, call 911.
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