The name Riboflavin is derived from its chemical component of the sugar called D-ribose and is characterized by its yellow fluorescent pigment. Riboflavin is stable in heat, but sensitive to light. Like the other water-soluble vitamins, Riboflavin is not abundantly stored in the body because excess amounts are easily excreted in the urine and is evident in a fluorescent yellow color. As mentioned, B-complex vitamins have multi-faceted functions. For example, Riboflavin works hand-in-hand with other B-complex vitamins in the breakdown of carbohydrate, protein and fat for energy. Riboflavin is believed to be helpful in the absorption of iron in treating anemia. Riboflavin is needed in the conversion of the amino acid Tryptophan to Niacin for normal cell function. Therefore, an absence of Riboflavin will affect the other nutrients' ability to work.

Functions

Riboflavin (Vitamin B2) is made up of two enzymes (coenzymes) called flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are important in energy production. These coenzymes work as catalysts in the electron transport system, which result in the formation of a primary energy currency in the cell, called adenosine triphosphate (ATP). Thus, the ultimate product is energy.

Riboflavin is also essential in the making of fatty acid and amino acid. As mentioned in the earlier sections that fats and protein are important in the body. The role of fats in the absorption of fat-soluble vitamins and in hormonal processes contrasts with the role of protein in muscle structures. For example, the synthesis of fatty acid (from fats) and amino acid (from protein) results in cellular growth; therefore, without Riboflavin this process would not happen. The production of certain hormones and the formation of red blood cells require the help of B-complex vitamins, such as Riboflavin. This explains why Vitamin B2 is helpful in the treatment of anemia.

Deficiencies

So far, there has been no reported specific Vitamin B2 deficiency. This is because Riboflavin (Vitamin B2) is involved with multiple nutrients and their functions. In order to activate the function of the other B-vitamins, Riboflavin must be present and vice versa. Therefore, a deficiency of Vitamin B2 could also mean deficiencies of other B-vitamins. There is an exception, of course. For example, newborn infants who are given phototherapy to treat a condition called hyperbilirubinemia become deficient in Riboflavin. This is because as mentioned, Riboflavin is sensitive to light and phototherapy involves the use of light. Reported symptoms associated with inadequate intake of Riboflavin (Vitamin B2) are as follows:

• Cheilosis - cracking at the corners of the mouth and inflammation of the mucous membranes in the mouth
• Glossitis - swollen and reddened tongue
• Corneal Vascularization - reddening, burning, itching of the eyes and sensitivity to light
• Seborrheic Dermatitis - unusual dryness and greasy scaling of the skin
• Nerve tissue damage - associated with depression
• Decreased neurotransmitter production - which may affect mental function
• Abnormal growth in infants and children

Toxicity

Riboflavin (Vitamin B2) is a water-soluble vitamin that is easily excreted in the urine, and as such, it is least likely to reach toxic levels. There have been no toxicity symptoms reported relating to excessive intake of Riboflavin.

The Recommended Dietary Allowance (RDA)

Since Riboflavin (Vitamin B2) plays an important role in energy production, the RDA is measured in terms of the total calories eaten. As mentioned earlier, Riboflavin is essential in the synthesis of amino acid and fatty acid, which are needed for cellular growth. Therefore, Riboflavin requirement must equal to the total energy needs and metabolism. However, the body's requirement for Riboflavin is increased during pregnancy, lactation, and heavy exercise. The safe RDA for Riboflavin (Vitamin B2) is 0.6 mg per 1,000 calories.

Food Sources

Riboflavin (Vitamin B2) is found in a variety of food sources, however, in small amounts. The most abundant sources of this vitamin are milk, milk products and liver. Other food sources of Riboflavin are oysters, lean meat, green leafy vegetables, mushrooms, asparagus, broccoli, avocados, Brussels sprouts and salmon.

Riboflavin is reported to be stable to heat, therefore, it is least likely lost during cooking. However, baking soda is reportedly destructive to the vitamin stability when it is added during cooking. In addition, because this vitamin is sensitive to light, the storage of such foods in clear containers may destroy the vitamin.

-- Ofelia B. Mutia, M.S.,R.D.,L.D.

Resources and Acknowledgments

1. Understanding Normal & Clinical Nutrition by Whitney, Cataldo & Rolfes
2. The Essential Guide to Vitamins and Minerals by Elizabeth Somer, M.A.,R.D.
3. Nutrition Concepts & Controversies by Hamilton, Whitney & Sizer
4. Advanced Nutrition and Human Metabolism by James L. Groff, Sareen S. Gropper
5. Bowes & Church's Food Values of Portions Commonly Used by Jean A.T. Pennington, Ph.D., Anna De Planter Bowes, Helen N. Church
6. Essentials of Nutrition and Diet Therapy by Sue Rodwell Williams
7. The Nutrition Desk Reference (3rd Edition) by Garrison, Robert Jr., M.A., R.Ph., and Somer, Elizabeth, M.A., R.D.