Comprehensive Guide to Vitamin B2 - Riboflavin

Vitamin B2-RiboflavinDr. James Meschino DC, MS, ND
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Riboflavin is a yellow-green fluorescent pigment that is responsible for the bright yellow urine that accompanies supplementation with this B-vitamin.

Absorption and Metabolism
Riboflavin is easily absorbed in the proximal small intestine. Only 15% is absorbed when taken alone and 60% of a 30 mg dose is absorbed when taken with food. It is phosphorylated to flavin mononucleotide (FMN) in the intestinal cells, and then carried into the bloodstream. The amount of riboflavin stored in the liver and kidneys is minimal, and therefore, it must be regularly supplied in the diet.


Energy Metabolism: in the form of FMN and FAD, these derivatives of Vitamin B2 are the prosthetic group of flavoproteins, involved in energy production within the mitochondria of the cell. They catalyze the first step in oxidative phosphorylation to help generate ATP energy.

Glutathione Formation

Steroid synthesis and amino acid metabolism

Red Blood Cell Production

Activates Vitamin B6 and folic acid: acts as a coenzyme to convert Vitamin B6 and folic acid to their active biological forms in the body.

Classical B2 Deficiency
Growth retardation: severe deficiency

Cheilosis: cracks at corners of the mouth

Glossitis: smooth and purplish tongue

Inflamed mouth

Dry, scaly facial skin

Seborrheic dermatitis, especially the nose-labial folds1

Low levels linked to esophageal cancer2
Recommended Daily Allowance (Vitamin B2)
Age Group and GenderVitamin B2 (mg)
Healthy adults1.5-1.8
Infants (<6 months)0.4
Infants (6-12 months)0.5
Children 1-10 years0.8-1.2 (progressive intake)1


Riboflavin Supplementation (above RDA)

Migraine Prevention

49 migraine patients were treated with 400 mg of Riboflavin for at least 3 months. A 68.2 percent improvement in frequency and duration of headache was reported in this group. The researchers indicated that there were no serious side effects from B2 treatment at this dosage and the treatment was well tolerated and effective.3

Cataract Protection

In one trial of Chinese subjects known to have sub-optimal intakes of Vitamin B2, older individuals supplemented with 3 mg of Vitamin B2 and 40 mg B3 per day demonstrated partial protection against cataracts.4

Mouth Ulcers (Apthous Stomatitis)

Supplementing with 300 mg Vitamin B1, 20 mg Vitamin B2 and 150 mg Vitamin B6 has been reported to provide relief and faster healing in some people.5

Adverse Side Effects and Toxicity

No toxicity or side effects from Riboflavin supplementation have been demonstrated.6,7

Drug - Nutrient Interactions
  1. Tricyclic Antidepressants

    Animal studies report that these drugs reduce the conversion of Riboflavin to its active form (e.g. amitriptyline, imipramine), which may increase Vitamin B2 requirement.8

  2. The following drugs are reported to cause riboflavin depletion:

    Antibiotics: antibiotics reduce B-vitamin synthesis by bacterial flora9,10

    Oral contraceptives11,12

    Chlorpromazine: animal studies indicate that this drug increases Riboflavin elimination13

Standard Textbooks of Nutritional Science:

   - Shils M, Shike M, Olson J and Ross C. Modern Nutrition in Health and Disease. 9th ed. Baltimore, MD: Lippincott Williams & Wilkins; 1993.

   - Escott-Stump S and Mahan LK, editors. Food, Nutrition and Diet Therapy. 10th ed. Philadelphia, PA: W.B. Saunders Company; 2000.

   - Bowman B and Russell RM, editors. Present Knowledge in Nutrition, 8th ed. Washington, DC:.ILSI Press; 2001.

   - Kreutler PA and Czajka-Narins DM, editors. Nutrition in Perspective. 2nd ed. Upper Saddle River, NJ: Prentice Hall Inc.; 1987.

Munoz N, Hayashi M, Bang LJ, Wahrendorf J, Crespi M, Bosch FX. Effect of Riboflavin, Retinal, and Zinc on the micronuclei of buccal mucosa and of esophogus. J Natl Cancer Inst 1987;79:687-91.

Schoenen J, Lenaerts M, Bastings E. High-dose Riboflavin as a prophylactic treatment of migraine: results of an open pilot study. Cephalalgia 1994;14:328-9.

Sperduto RD, Hu TS, Milton RC, Zhao JL, Everett DF, Cheng QF, et al. The linxian cateract studies. Arch opthlalmol 1993; III:1246-53.

Nolan A, McIntosh WB, Allam BF, Lamey. Recurrent apthous ulceration. J Oral Pathol Med 1991;20:389-91. Kreutler PA, Czajka-Narins D.M. Nutrition in Perspective. 2nd ed. Englewood Cliffs, NJ: Prentice Hall; 1987. p. 218.

Krause M and Mahan K. Food Nutrition and Diet Therapy. 7th ed. Philadelphia, Pa: W.B. Saunders Company; 1984.

Pinto J, Huang YP, Pelliccione N, Rivlin RS. Cardiac sensitivity to the inhibitory effects of chlorpromazine, imipramine and amitriptyline upon formation of flavins. Biochem Phamocol 1982;31(21):3495-9.

Cumings JH, Macfarlane G. Role of intestinal bacteria in nutrient metabolism. J Parenter enteral nutr 1997;21(6):357-65.

Deguchi Y, Morishita T, Mutai M. Comparative studies on synthesis of water-soluble vitamins among species of bifidobacteria. Agric Boil Chem 1985;49(1):13-9.

Webb JL. Nutritional effects of oral contraceptive use: a review. J Reprod Med 1980;25(4):150-6.

Newman LJ, Lopez R, Cole HS, et al. Riboflavin deficiency in women taking oral contraceptive agents. Am J Clin Nutr 1978;31(2):247-9.

Pelliccione N, et al. Accelerated development of riboflavin deficiency by treatment with chlorpromazine. Biochem Pharmacol 1983; 32(19):2949-53.