Riboflavin, or vitamin B-2, is a member of the B complex family. Riboflavin is a water-soluble, vibrantly yellow vitamin, which accounts for the fluorescent yellow-green urine of people who take vitamin B complex supplements. Riboflavin is not stored in significant amounts in your tissues, so you need to acquire this nutrient from your diet on a regular basis. However, according to Dr. Elson Haas, author of "Staying Healthy with Nutrition," some riboflavin is synthesized by the bacteria in your intestine, so serious deficiencies are uncommon.
Riboflavin serves as the precursor for two coenzymes needed for energy production in your cells. Flavin mononucleotide, or FMN, and flavin adenine dinucleotide, or FAD, are vital participants in the metabolism of fats and carbohydrates to produce ATP, a high-energy molecule needed by all cells. Riboflavin also helps your cells to convert the amino acid tryptophan to niacin, another B vitamin, and it is needed to activate vitamin B-6, or pyridoxine. Finally, as outlined in the April 2011 issue of the "International Journal of Oncology," riboflavin is needed to recycle glutathione, which is an important antioxidant in your cells.
The best food source of riboflavin is brewer's yeast. Other excellent sources include liver, tongue, heart and all organ meats. Nori seaweed and oily fish, such as trout, herring, mackerel and eel contain substantial amounts of riboflavin. Milk products, eggs, dried legumes, wild rice, millet and shellfish contain somewhat smaller amounts. Dark leafy greens are reasonable sources of riboflavin. Riboflavin is commonly included in vitamin B complex supplements; you can also purchase it as a single nutrient.
Although some riboflavin is produced by your intestinal bacteria, deficiencies can occur in certain situations. Alcoholics, elderly persons, the impoverished, people who rely on highly-processed foods and depressed individuals may not consume enough of the right foods to meet their riboflavin needs. In addition, you could become deficient if you take antibiotics for extended periods of time. The most common signs of riboflavin deficiency are a breakdown of the skin and mucous membranes at the corners of your mouth and edges of your lips. Your tongue darkens and becomes tender, and you develop dermatitis of the face, scalp, ears, eyelids and genital area. Eye inflammation may also occur.
Riboflavin deficiency often occurs in conjunction with other B vitamin deficiencies, so you should discuss the treatment of other B vitamin deficiencies with your doctor if you are diagnosed with a riboflavin deficiency. A measurement of urinary riboflavin can confirm a riboflavin deficiency. To treat a deficiency, oral riboflavin doses of 2 to 10 mg are administered 3 times daily until signs and symptoms improve, and then the dose is reduced to 2 to 4 mg once daily until you completely recover. If oral supplements are ineffective, riboflavin injections can be given. Daily riboflavin requirements for adults vary from 1 to 1.6 mg, with the higher doses recommended for pregnant and lactating women.