Vitamin B2

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Latest Edit: Hector 2014-03-17 (EDT)

See Also Vitamins


Vitamin B2, or Riboflavin to which it is also referred, is a water-soluble micronutrient. It plays an important role in energy production in the body as well as being involved in glutathione regeneration.

Food Sources

Other food sources include:[1]

Riboflavin is destroyed by light but not by cooking.


The following are the primary uses of Vitamin B2.[2] [3]

Deficiency Symptoms

Deficiency in Riboflavin is rare, however, low levels are common in the elderly. Symptoms of deficiency include:

  • cracking of the lips and corner of the mouth
  • inflamed tongue
  • visual disturbances such as sensitivity to light and loss of visual acuity
  • cataract formation
  • burning and itching of the eyes, lips, mouth, and tongue
  • signs of disorders of mucous membranes
  • can also produced anemia and seborrheic dermatitis

Excess Symptoms

Riboflavin, in excess, is excreted in the urine and is responsible for turning urine a bright yellow-green fluorescent colour but is not associated with toxicity.

Assessment Procedure

Common deficiency tests: [4]

  • Alpha-Keto acids urine test - a high level indicates a deficiency
  • Ethylmalonate urine test - a high level indicates a deficiency
  • EGR Activity Coefficient

Prescribing Considerations

  • Riboflavin is available in supplemental for as simple riboflavin and activated riboflavin (riboflavin-5-phosphate). [2]
  • The recommended dosages varies based on age and health status. To determine what your specific requirements are talk to your naturopathic doctor or other trained medical professional.
  • Infants: 0.4mg (under 6 months); 0.5mg (6-12 months)
  • Child: 0.8mg (1-3 years); 1.1mg (4-6 months); 1.2mg (7-10 years)
  • Adolescent: 1.5mg (Males 11-14 years); 1.8mg (Males 15-18 years)
  • Adult: 1.7mg (Males 19-50 years); 1.3mg (Females 11-50 years); 1.4mg (Males 51+ years); 1.2mg (Females 51+ years)
  • Pregnancy: 1.6mg
  • Lactation: 1.8mg


  • Children: no adverse effects
  • Pregnancy and Breastfeeding: vitamin B2 is excreted in breast milk but is generally considered safe in both pregnancy and during nursing.

Drug Interactions

Drug interactions include:[5]

Supportive or Beneficial:
  • Thyroid Hormones - Hypothyroidism and riboflavin deficiency share many characteristics. T3 enhances biosynthesis of active vitamin B2. Thyroid status appears to influence activity of riboflavin (and folate and response to tricyclic antidepressants and phenothiazines. Co-administration may be beneficial.
  • Tricyclic Antidepressants (TCAs) - Drug can adversely affect vitamin activity and increase requirements by impairing absorption and inhibiting conversion to active form. Co-administration may prevent or reverse depletion as well as augment clinical response to TCAs through an additive or synergistic effect.
Addresses Drug-Induced Deficiency:
  • Anticonvulsant Medications and Related Barbiturates - Drug may alter riboflavin metabolism and interfere with activity of riboflavin-related enzymes and deplete the vitamin. Co-administration can mitigate adverse effects. Requires clinical management.
  • Antiretroviral Agents, Nucleoside (Analog) Reverse-Transcriptase Inhibitors (NRTIs or NNRTIs) - Drug-induced mitochondrial toxicity associated with riboflavin deficiency contributes to lactic acidosis in patients treated with NRTIs. Co-administration, preferably with Thiamine can be beneficial. Supervise closely and monitor regularly.
  • Boric Acid, Borate, and Boron - Drug tends to complex with vitamin B2 and thereby reduce absorption and increase urinary excretion. Separate intake of boron/boric acid and riboflavin unless binding is intentional as with boric acid poisoning.
  • Chloropromazine and Related Phenothiazine Antipsychotics - Drug can inhibit conversion of Riboflavin to its active forms and/or can cause binding and increased excretion. Consider co-administration of Riboflavin (and folic acid especially in unipolar depression. Separate intake (due to potential decrease bioavailability of drug when taken together). Evaluate and monitor Riboflavin, FAD, and thyroxine status (when deficient, all can be linked to unipolar depression).
  • Doxorubicin and Related Anthracycline Chemotherapy - Drug can inhibit conversion to vitamin's active forms and/or binding and excretion may also occur. Sunlight exposure in the presence of riboflavin may deactivate doxorubicin. Co-administration, especially with CoQ10, can be beneficial but may not be adequate. Separate intake (due to potential decrease bioavailability of drug when taken together). Sunlight avoidance may be prudent with co-administration. Supervise closely.
  • Oral Contraceptives: Monophasic, Biphasic, and Triphasic Estrogen

Preparations (Synthetic Estrogen and Progesterone Analogs) - Drug may reduce levels of vitamin B2 (as well as B6, folate, and B12). Co-administration of a B-complex formulation can be beneficial.

  • Probenecid - Drug can impair absorption in GI tract, inhibit renal tubular secretion, and decrease urinary excretion. Co-administration especially with nutritionally compromised patients and with long-term therapy. Monitor for signs of deficiency.
  • Antimalarial Drugs - Low vitamin B2 status is protective against malaria and advantageous in reducing the severity of malarial symptoms. Vitamin B2 is generally contraindicated in both prevention and treatment. Further research is needed as riboflavin may actually be protective against Plasmodium falciparum.
  • Propantheline Bromide (Pro-Banthine) - Drug elevates vitamin B2 levels by decreasing salivary flow and decreasing rate of gastric emptying and GI motility. No response necessary. Patients need not avoid vitamin B2 in multivitamin.
  • Tetraycline and Other Antibiotics - Simultaneous intake of vitamin B2 and other B vitamins with the drug can reduce absorption and bioavailability of both/all agents. Antibiotic effect on gut flora ecology can produce secondary adverse effects on B-vitamin status and inflammatory processes. Separate intake. Probiotic flora is beneficial after antibiotic therapy.

Nutrient Interactions

Nutrient interactions include: [5]


  1. Medlineplus [1]
  2. 2.0 2.1 Murray Michael T (2005) Encyclopedia of Nutritional Supplements, The Essential Guide for Improving Your Health Naturally, Prima Publishing
  3. Hoffer Abram, Prousky Jonathan (2006) Naturopathic Nutrition, a Guide to Health Food and Nutritional Supplements, CCNM Press
  4. Bralley J Alexander and Lord Richard S (2005) Laboratory Evaluations in Molecular Medicine, Nutrients, Toxicants, and Cell Regulators Institute for Advances in Molecular Medince, GA
  5. 5.0 5.1 Stargrove Mitchell Bebell, Treasure Jonathan, McKee Dwight L (2008) Herb, Nutrient, and Drug Interactions, Clinical Implications and Therapeutic Strategies. Mosby