- Vitamin B2 (riboflavin) information Linus Pauling Institute
- Vitamin B1 (thiamine) overview Linus Pauling Institute
- Vitamin B2 health properties, benefits, side effects Natural Medicines Comprehensive Database
- List of foods high in vitamin B2 USDA.gov
- Vitamin B2 deficiency symptoms Emedicine
- Decreased thyroid activity and riboflavin deficiency PubMed
- Vitamin B2 pregnancy category Drugs.com
- Vitamin B2 and work performance The National Academic Press
- Effect of storing and cooking on vitamin B2 content of foods PubMed
- Riboflavin in fortified foods is GRAS U.S. Food and Drug Administration
- Riboflavin is vegan Vrg.org
- Riboflavin can color the stool yellow The National Academic Press
- Riboflavin deficiency in low-protein diet in kidney failure PubMed
- Vitamin B2 safety in pregnancy and breastfeeding Medscape
- Riboflavin, magnesium and feverfew for migraine pain PubMed
- Riboflavin absorption and excretion National Institute of Health
- Vitamin B-complex Food and Agriculture Organization (FAO)
Vitamin B2 (Riboflavin)
Vitamin B2 (Riboflavin) Quick Facts
- Vitamin B2 is an essential nutrient involved in production of energy from food, metabolism of glucose and maintaining healthy skin.
- Healthy individuals, including pregnant and breastfeeding women and vegans can get sufficient amounts of vitamin B2 by eating variety of foods, so they do not likely need supplemental vitamin B2.
- Chronic alcoholics and, rarely, people who do not eat enough can develop vitamin B2 deficiency (ariboflavinosis) with magenta red tongue and oily, scaly skin.
- Vitamin B2 supplements help in vitamin B2 deficiency and, possibly, in preventing migraine and cataracts but less likely in other health disorders.
Recommended Daily Intake
The Recommended Dietary Allowance (RDA) for vitamin B2 for adult men is 1.3 mg/day, for women 1.1 mg/day, 1.4 mg/day during pregnancy and 1.6 mg/day during breastfeeding .
Food Sources of Vitamin B2
Most common foods contain at least small amounts of riboflavin.
Foods HIGH in vitamin B2:
- PLANT FOODS: fortified ready-to-eat cereals (0.5-6 mg/cup), yeast extract spread (2.2 mg/tbsp), vegetarian fillets (0.8 mg/3 oz), cornmeal (0.6 mg/cup), pasta (0.6 mg/130 g), orange and grape juice (1.1 mg/cup), dark green leafy vegetables: spinach, broccoli (0.1-0.4 mg/cup).
- ANIMAL FOODS: beef liver (3 mg/3 oz), chicken liver (2 mg/3 oz), mollusks (1.5 mg/3 oz), whey, dried, acid (1.2 mg/cup), beef/game/goose meat (0.3-0.8 mg/3 oz), salmon, red (0.5 mg/3 oz), cheese, Monterey, Swiss (0.5 mg/cup), milk (0.5 mg/cup), eggs (0.3 mg/egg)
- Breast milk from well nourished mothers should provide enough riboflavin (~0.4 mg/liter) for exclusively breastfed infants in their first 6 months [1,4].
NOTE: 1 oz = 28 g, 1 cup = 237 mL
Common foods low in vitamin B2: unfortified white rice, most fruits (apples, pears, plums).
Riboflavin in fortified foods is safe and vegan
In the United States, flour (baked products), morning cereals and certain chocolate bars and beverages are fortified with riboflavin or riboflavin phosphate, which are typically synthetically or microbially produced, so they are vegan ; in rare occasions they may be animal derived — you may need to contact the producer to find this out. Riboflavin and riboflavin 5-phosphate are Generally Recognized As Safe (GRAS) by the US Food and Drug Administration (FDA) .
Cooking and exposure to ultraviolet light (UV), including daylight, for few hours can destroy quite some riboflavin in the foods, but storing in a dark place for several months may have no significant effect [1,9].
References: Linus Pauling Institute , USDA.gov 
Vitamin B2 Deficiency (Ariboflavinosis): Who is at risk?
- Chronic alcoholics and people who starve or suffer from anorexia nervosa
- Individuals with celiac or Crohn’s disease, HIV/AIDS, liver disease, cancer , individuals with chronic kidney failure on low-protein diet ,
- In poor regions of Africa and Asia: children with gastrointestinal infections 
- Individuals with hypothyroidism  or adrenal insufficiency, which make vitamin B2 less effective
- Premature infants with neonatal jaundice on phototherapy 
Vitamin B2 Deficiency Symptoms and Signs
Symptoms of vitamin B2 deficiency, which can appear within few weeks of reduced vitamin intake:
- Sore and magenta red tongue and throat (glossitis)
- Cracks in the corners of the lips (angular stomatitis or cheilosis)
(picture source: Wikipedia, author: James Heilman, MD)
- Oily, scaly skin around the nose and scrotum (seborrheic dermatitis)
- Vessels growth in the eye cornea, itchy eyes, night blindness
- In severe cases, paleness and fatigue due to anemia
References: Linus Pauling Institute , Natural Medicines Comprehensive Database 
Vitamin B2 deficiency is a risk factor for cataracts, migraine, peripheral neuropathy, night blindness, iron-deficiency anemia, heart disease, high blood pressure, preeclampsia (high blood pressure and edema in pregnancy), birth defects (cleft lip and palate, growth retardation), esophageal and cervical cancer [1,5].
Vitamin B2 deficiency is usually accompanied with deficiencies of other B-complex vitamins .
Diagnosis and Treatment
Vitamin B2 deficiency is diagnosed by a blood test . Treatment is with vitamin B2 supplements.
Vitamin B2 (Riboflavin) Supplements
By mouth (available over-the-counter)
Oral vitamin B2 in the form of tablets, capsules, softgels, lozenges, powder or liquid containing riboflavin or riboflavin-5-phosphate (monophosphate) are available without prescription. Vitamin B2 is also usually included in vitamin B-complex, prenatal and multivitamin supplements.
Tablets or capsules may contain 10, 15, 20 100, 200, 250, 300 or 400 mg of vitamin B2.
Can vitamin B2 supplements be good for you?
Vitamin B2 supplements are effective in:
- Preventing and treating riboflavin deficiency
Vitamin B2 supplements are possibly effective in:
- Reducing the migraine attack frequency, but less likely intensity and duration; it may take few months for supplements to take maximal effect; in children no effects were observed.
- Preventing cataracts
- Genetic metabolic disorders: multiple acyl-CoA dehydrogenase deficiency (MADD), riboflavin-responsive trimethylaminuria
References: Linus Pauling Institute , Natural Medicines Comprehensive Database 
There is insufficient evidence about vitamin B2 supplements effectiveness in prevention or treatment of HIV/AIDS-related lactic acidosis, cervical cancer, acne, hair loss, muscle cramps, canker sores, memory loss, Alzheimer’s disease, burns, alcoholism, liver disease or sickle cell anemia; increasing energy levels or athletic performance, boosting the immune system, promoting weight loss, slowing aging or improving skin (rosacea) or nail health [3,8].
Recommended Riboflavin Dosage in Adults
- For riboflavin deficiency, tablets 5-30 mg/day
- For preventing migraine headache, tablets 400 mg/day
- For preventing cataracts 2.6 mg/day, optionally in combination with vitamin B3 (niacin) 40 mg/day. NOTE: Vitamin in doses higher than 10 mg/day may worsen cataracts .
- Reference: 
Vitamin B2 Supplements Safety: Side Effects, Toxicity
No toxic effects of vitamin B2 supplements were identified so far . High doses (400 mg/day) may trigger diarrhea and excessive urination (polyuria) in some people . Vitamin B2 supplements can give urine and stool fluorescent bright yellow or orange color (flavinuria), which causes no harm [1,12]. No Tolerable Upper Level for riboflavin has been set, because overdose has not been observed . Any vitamin B2 taken in excess is excreted with urine .
Overconsumption of vitamin B2 from foods is practically impossible; even by eating a lot of fortified foods you will not likely get too much vitamin B2.
Safety During Pregnancy and Breastfeeding
Vitamin B2 by mouth in doses within Recommended Daily Allowance (1.4 mg/day) is pregnancy category A, which means no harmful effects for the babies were observed during human trials, and doses above 1.4 mg/day are pregnancy category C, which means, insufficient human trials were made to prove its safety at these doses [7,14].
Vitamin B2 is safe to use during breastfeeding .
Vitamin B2 Interactions With Drugs and Nutrients
The following drugs may reduce vitamin B2 activity: quinine, chlorpromazine, tricyclic antidepressants, adriamycin, phenobarbitol .
In individuals with vitamin B2 deficiency and anemia, vitamin B2 supplements increase bioavailability of iron .
Vitamin B2 is required for proper action of vitamins B3 (niacin), B6 (pyridoxine), B9 (folic acid), B12, iron and zinc .
Vitamin B2 Absorption and Body Stores
- Vitamin B2 is water-soluble so it can not be stored in the body fat and can be therefore depleted from the body in several weeks.
- Vitamin B2 is absorbed in the upper small intestine (jejunum); absorption is much better when taken with foods .
Frequently Asked Questions
1. What are other names for vitamin B2?
The other name for vitamin B2–riboflavin–originates from ribose, which is a component of vitamin B2 molecule, and the Latin word for yellow–flavus–because vitamin B2 as a compound is yellow .
2. What is riboflavin mechanism of action and function?
Riboflavin acts as an activating substance (cofactor, coenzyme) for enzymes involved in tissue respiration and thus production of energy from carbohydrates, proteins and fats . It is also involved in the metabolism of vitamin B3 (niacin), B6 (pyridoxine), B9 (folate) and iron .
3. What are health benefits of high vitamin B2 doses (400 mg/day)?
Riboflavin in a dose 400 mg/day may help reduce migraine headache frequency in adults . However, in one 2004 study, a combination of riboflavin 400 mg, magnesium 300 mg and feverfew herb extract 100 mg was not more effective than 25 mg of riboflavin alone .
4. Is vitamin B2 an antioxidant?
On the level of the chemical reactions, vitamin B2 acts as an antioxidant, but no health benefits of vitamin B2 supplements related to its antioxidant activity have been proven so far in humans .
- Vitamin A - Retinol and retinal
- Vitamin B1 - Thiamine
- Vitamin B2 - Riboflavin
- Vitamin B3 - Niacin
- Vitamin B5 - Pantothenic acid
- Vitamin B6 - Pyridoxine
- Vitamin B7 - Biotin
- Vitamin B9 - Folic acid
- Vitamin B12 - Cobalamin
- Vitamin C - Ascorbic acid
- Vitamin D - Ergocalciferol and cholecalciferol
- Vitamin E - Tocopherol
- Vitamin K - Phylloquinone
- Hydrogenated starch hydrolysates (HSH)
- Fructo-oligosaccharides (FOS)
- Galacto-oligosaccharides (GOS)
- Human milk oligosaccharides (HMO)
- Isomalto-oligosaccharides (IMO)
- Mannan oligosaccharides (MOS)
- Raffinose, stachyose, verbascose
- SOLUBLE FIBER:
- Acacia (arabic) gum
- Beta mannan
- Carageenan gum
- Carob or locust bean gum
- Fenugreek gum
- Gellan gum
- Glucomannan or konjac gum
- Guar gum
- Karaya gum
- Psyllium husk mucilage
- Resistant starches
- Tara gum
- Tragacanth gum
- Xanthan gum
- INSOLUBLE FIBER:
- Chitin and chitosan
- Aspartic acid
- Glutamic acid
- FATTY ACIDS
- Alpha-linolenic acid (ALA)
- Eicosapentaenoic (EPA) and Docosahexaenoic acid (DHA)
- Arachidonic acid (AA)
- Linoleic acid
- Conjugated linoleic acid (CLA)
- Short-chain fatty acids (SCFAs)
- Medium-chain fatty acids (MCFAs)
- Long-chain fatty acids (LCFAs)
- Very long-chain fatty acids (VLCFAs)
- Flavanols: Proanthocyanidins
- Flavanones: Hesperidin
- Flavonols: Quercetin
- Flavones: Diosmin, Luteolin
- Isoflavones: daidzein, genistein
- Caffeic acid
- Chlorogenic acid
- Tannic acid
- Alcohol chemical and physical properties
- Alcoholic beverages types (beer, wine, spirits)
- Denatured alcohol
- Alcohol absorption, metabolism, elimination
- Alcohol and body temperature
- Alcohol and the skin
- Alcohol, appetite and digestion
- Neurological effects of alcohol
- Alcohol, hormones and neurotransmitters
- Alcohol and pain
- Alcohol, blood pressure, heart disease and stroke
- Women, pregnancy, children and alcohol
- Alcohol tolerance
- Alcohol, blood glucose and diabetes
- Alcohol intolerance, allergy and headache
- Alcohol and psychological disorders
- Alcohol and vitamin, mineral and protein deficiency
- Alcohol-drug interactions
- Moderate, heavy, binge drinking
- Alcohol intoxication
- Alcohol poisoning
- Alcohol and gastrointestinal tract
- Alcoholic liver disease
- Long-term effects of excessive alcohol drinking
- Alcohol craving and alcoholism
- Alcohol withdrawal