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Vitamin B2 (Riboflavin)

What is vitamin B2?

This vitamin is more commonly known by its name rather than its number. You probably know it as riboflavin.

What does the body use Riboflavin for?

The B2 vitamin, similarly to B1 (thiamin), is used to help our body maintain energy metabolism and cellular health. B2 is also essential for cell reproduction and growth. Riboflavin also plays a role in tissue respiration, which is the process by which cells receive and exchange oxygen.

Dietary Reference Intakes (DRIs)

The amount of riboflavin you need depends on your sex and age.

Helpful terms to know

  • Recommended Dietary Allowance (RDA): covers the needs of 97-98% of individuals in a group; the average amount of a nutrient a healthy person should consume daily. Vary by gender, age, and whether a woman is pregnant or breastfeeding. Developed by the Food and Nutrition Board at the Institutes of Medicine (IOM) of the National Academies.

  • mcg = microgram


Since riboflavin is essential to metabolism, even at the cellular level, symptoms of deficiency are understandably most noticeable in tissue with a high level of cellular turnover, such as the skin.

Who is at risk for a riboflavin deficiency?

Individuals that may be prone to a deficiency of B2 generally fall in the following categories:

  • Vegetarian athletes

  • pregnant/lactating women

  • Infants

  • vegan

  • Infants with Brown-Vialetto-Van syndrome (very rare neurological disorder)

How long after suffering from a deficiency do symptoms start to appear?

Symptoms of a lack of vitamin B2 can become evident after several months of deficiency. Deficiency of riboflavin normally occurs in conjunction with deficiencies of other vitamins, especially in cases of malnutrition.

Symptoms of deficiency

Early Stages

  • Photophobia

  • Tearing

  • Burning and itching of the eyes

  • Loss of visual acuity (sharpness)

  • Soreness or burning of the lips, mouth, and tongue

Advanced Stage

  • Fissuring of the lips (cheilosis)

  • Cracks in the skin at the corners of the mouth (angular stomatitis)

  • Greasy eruption at skin folds (i.e. nasolabial folds, scrotum, vulva)

  • Purple, swollen tongue

  • Capillary overgrowth around the cornea of the eye

  • Peripheral neuropathy (weakness, numbness, and pain due to nerve damage in the extremities such as hands or feet)


Riboflavin has not yet been present in cases of toxicity, however it is known that high doses are not beneficial. Stay within the RDA for your respective age and gender to know the amount of riboflavin you should consume daily. If you have questions, consult your dietitian or a trusted, vitamin-literate member of your healthcare team. Oral doses up to 400 mg of riboflavin have been consumed in patients with migraines without side effects, however this should be done under supervision of a medical professional and not as a home experiment. Talk with your physician and dietitian before increasing your normal dose.

How to determine levels of riboflavin

These tests should be run under direct medical supervision. Ask your doctor and dietitian for more information. You riboflavin status can be assessed through measurement of the following:

  • Most sensitive: measuring the activity of FAD-dependent enzyme erythrocyte glutathione reductase (activity of this enzyme is limited in cases of riboflavin deficiency or marginal riboflavin status

  • Additional measurements:

    • FMN-dependent enzyme activity

    • Pyridoxamine phosphate oxidase activity (appears to be a biomarker for riboflavin status)

    • Urinary riboflavin excretion- Less than 25 mcg riboflavin/g creatinine (without recent riboflavin intake) or less than 40 mcg riboflavin/day is considered indicative of deficiency

It’s perfectly okay if these types of tests sound like gibberish to you. Take this list to your healthcare professionals and they will be able to determine which ones will be appropriate for you and can tell you more about each of them.

Sources of Riboflavin

How stable is Riboflavin?

Riboflavin is stable when exposed to heat, oxygen, and acid. However, it is unstable in the presence of light (especially ultraviolet [UV]) or alkali.

Supplementation & Treatment with Riboflavin


Conflicting evidence exists on potential uses for riboflavin. Some studies show that riboflavin may be useful in preventing migraines, however evidence as of now is inconclusive. What experts know for certain is that riboflavin is vital to overall health and energy metabolism.

Brown-Vialetto-Van syndrome

For infants with this very rare neurological disorder, which is caused by a mutation in the gene encoding for intestinal riboflavin transportation, supplemental riboflavin can be a life-saving treatment.

Dietary Supplements

Multivitamin and multimineral supplements generally provide about 1.3 mg of riboflavin, which accounts for 100% of the estimated daily value. For B-vitamins, B-complex supplements (that include riboflavin) may also be available. Be sure to check the label of any supplement you intend on consuming before ingestion.


The Dietary Guidelines for Americans suggest trying to obtain your daily amount of vitamins, including riboflavin, first from food (such as the sources listed above). Unnecessary supplementation can interact with other medicines and how your body processes nutrients, so consult with your healthcare team before starting a riboflavin supplement to see if you are truly in need of taking one.


FREE Patient Resources

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Related Professional Resources

Don't you wish you had a quick reference to brush up on riboflavin before seeing your clients or patients? This quick reference will help you organize your thoughts and prove to be a great resource in between appointments.   Upon purchase, a high quality pdf file will be available for download. From there, you can turn the file into a print-out, poster, or whatever you would like!

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Related Posts



  1. Pronsky ZM, Elbe D, Ayoob K. Food Medication Interactions (The Foremost Drug-Nutrient Interaction Resource), Micronutrient Food Sources. 18th Edition. 2015. ISBN: 978-0-9710896-6-2

  2. Hart J. Eat Pretty. Chronicle Books. 2014. ISBN 978-1452123660.

  3. Gropper SS, Smith JL, Carr TP. Advanced Nutrition and Human Metabolism, Seventh Edition. Cengage Learning. 2017. ISBN: 978-1305627857.

  4. Mahan KL, Raymond JL. Krause's Food & the Nutrition Care Process 13th Edition. 2011. Saunders. ISBN: 978-1437722338.

  5. Office of Dietary Supplements. Riboflavin, Fact Sheet for Consumers. National Institutes of Health. 2020. Accessed at

  6. Office of Dietary Supplements. Riboflavin, Fact Sheet for Professionals. National Institutes of Health. 2020. Accessed at

  7. Klemm S. What Are B-Vitamins. Academy of Nutrition and Dietetics. 2019. Accessed at


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