Comprehensive Guide to Vitamins by Dr. James Meschino - HTML preview

Vitamin B₂ - Riboflavin

Introduction

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.

Functions

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)

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 flora^9,10
   Oral contraceptives^11,12
   Chlorpromazine: animal studies indicate that this drug increases Riboflavin elimination¹³

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

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

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

- Kreutler PA and Czajka-Narins DM, editors. Nutrition in Perspective. 2^nd 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. 2^nd ed. Englewood Cliffs, NJ: Prentice Hall; 1987. p. 218.

Krause M and Mahan K. Food Nutrition and Diet Therapy. 7^th 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.