Riboflavin, also known as Vitamin B2, has many functions in common with the other members of the B complex family. These include support of the immune and nervous systems and formation of healthy red blood cells. Riboflavin provides essential factors for the production of cellular enzymes that turn proteins, fats, and carbohydrates into energy. It also participates in cell reproduction, and keeps skin, hair, nails, eyes, and mucous membranes healthy. Folic acid (vitamin B9) and pyridoxine (vitamin B6) are activated by riboflavin.
Recent research has found that riboflavin is one of three vitamins involved in the regulation of circadian (daily) rhythms in humans and other mammals. Riboflavin helps to activate certain light-sensitive cells in the retina of the eye that synchronize the animal's daily biological rhythms with the solar light/darkness cycle.
General use
The RDA of riboflavin for infants under six months is 0.4 milligrams (mg). It goes up incrementally with age and caloric intake. Babies from six months to one year of age require 0.5 mg. Children need 0.8 mg at one to three years of age, 1.1 mg at four to six years, and 1.2 mg at seven to ten years. Women need 1.3 mg from 11-50 years, and 1.2 mg thereafter. Slightly more is required for pregnancy (1.6 mg) and lactation (1.7-1.8 mg). Men require 1.5 mg from 11-14 years of age, 1.8 mg from 15-18 years, 1.7 mg from 19-50 years, and 1.4 mg at 51 years and older. Riboflavin is water-soluble, and is not stored in significant quantities in the body.
High doses of riboflavin, as much as 400 mg per day, have been shown to reduce the frequency of migraine headaches by half in susceptible people. The severity of the events was also reportedly decreased. This may be an effect of improved use of cellular energy in the brain. It is theorized that riboflavin may help decrease the odds of getting cataracts, but the evidence for this is not definitive. One large study had a group taking both niacin (vitamin B3) and riboflavin, and while the group had a significantly lower total incidence of cataracts, they had a somewhat higher than average incidence of a specific cataract subtype. Memory may be improved by these supplements, according to some research done on older people. Riboflavin and vitamin C both help boost the body's level of glutathione, which is an antioxidant with many beneficial effects. There is not enough evidence to support the effectiveness of riboflavin for sickle-cell anemia, canker sores, or as an athletic performance aid.
Natural sources
Beef liver is a very rich source of riboflavin, but dairy products also supply ample amounts. Higher fat sources contain less than those with low fat. Many processed grain products are fortified with riboflavin, as well as other B vitamins. Good vegetable choices include avocados, mushrooms, spinach, and other dark green, leafy vegetables. Nuts, legumes, nutritional yeast, and brewer's yeast contain riboflavin as well. Cooked foods provide as much of this vitamin as raw ones do, since the substance is heat stable. Light, however, does break down riboflavin. To preserve it, be sure to either store dairy and grain products in something opaque or keep them away from light.
Supplemental sources
Riboflavin is available as an oral single vitamin product. Consider taking a balanced B complex supplement rather than high doses of an individual vitamin unless there is a specific indication to do so. Store supplements in a cool, dry place, away from light, and out of the reach of children.
Deficiency
Ariboflavinosis is the term for the condition of vitamin B2 deficiency. Since small amounts can be stored in the liver and kidneys, a dietary inadequacy may not become apparent for several months. Insufficient levels of riboflavin have noticeable effects on several areas of the skin. Commonly the corners of the mouth are cracked. Facial skin and scalp tend to itch and scale, as does the scrotal skin. The eyes fatigue easily and are sensitive to light, and may also become watery, sore, or bloodshot. Trembling, neuropathy, dizziness, insomnia, poor digestion, slow growth, and sore throat and tongue have also been reported. Anemia may develop if the deficiency is severe. People who are deficient in riboflavin are likely to be lacking in other B vitamins, and possibly additional nutrients, as well.
Recent studies done at the National Cancer Institute indicate that riboflavin deficiency increases a woman's risk of developing cervical cancer. Further studies of this connection are underway.
Risk factors for deficiency
Riboflavin deficiency is uncommon in developed countries, but some populations may need more than the RDA in order to maintain good health. War refugees are a population at high risk for riboflavin deficiency. Vegans and others who do not use dairy products would do well to take a balanced B vitamin supplement; one study of Swedish vegans found that over 90% were not getting enough riboflavin in their diet. Those with increased need for riboflavin and other B vitamins may include people under high stress, including those experiencing surgery, chronic illnesses, liver disease, or poor nutritional status. Diabetics may have a tendency to be low on riboflavin as a result of increased urinary excretion. Athletes, and anyone else with a high-energy output will need additional vitamin B2. This includes anyone who exercises with some regularity. The elderly are more likely to suffer from nutritional inadequacy as well as problems with absorption; the dietary preferences of many elderly people often exclude foods that are high in riboflavin. Smokers and alcoholics are at higher risk for deficiency as tobacco and alcohol suppress absorption. Birth control pills may possibly reduce riboflavin levels, as can phenothiazine tranquilizers, tricyclic antidepressants, and probenecid. Consult a health care professional to determine if supplementation is appropriate.
Recent advances in human genetics indicate that certain genotypes are at greater risk for riboflavin deficiency than others.
Precautions
Riboflavin should not be taken by anyone with a B vitamin allergy or chronic renal disease. Other populations are unlikely to experience any difficulty from taking supplemental B2.
Side effects
Taking supplemental riboflavin causes a harmless intense orange or yellow discoloration of the urine.
Interactions
Probenecid (a drug treating gout) impairs riboflavin absorption, and propantheline bromide (a drug treating peptic ulcers) reportedly both delays and increases absorption. Phenothiazines (antipsychotic drugs) increase the excretion of riboflavin, thus lowering serum levels, and oral contraceptives may also decrease serum levels. Tricyclic antidepressants may lower the levels of riboflavin in the body. Supplementation should be discussed with a health care provider if these medications are being used. Absorption of riboflavin is improved when taken together with other B vitamins and vitamin C.
Riboflavin supplements may lower the effectiveness of chloroquine and other antimalarial medications. Riboflavin should not be taken at the same time as tetracycline antibiotics because it interferes with the absorption and effectiveness of these medications. It may also interfere with the effectiveness of sulfa-containing drugs used to treat bacterial infections.
BOOKS
Bratman, Steven, and David Kroll. Natural Health Bible. Prima Publishing, 1999.
Feinstein, Alice. Prevention's Healing with Vitamins. Pennsylvania: Rodale Press, 1996.
Griffith, H. Winter. Vitamins, Herbs, Minerals & Supplements: the complete guide. Arizona: Fisher Books, 1998.
Jellin, Jeff, Forrest Batz, and Kathy Hitchens. Pharmacist's letter/Prescriber's Letter Natural Medicines Comprehensive Database. California: Therapeutic Research Faculty, 1999.
Pressman, Alan H., and Sheila Buff. The Complete Idiot's Guide to Vitamins and Minerals. New York: Alpha books, 1997.
PERIODICALS
Blanck, H. M., B. A. Bowman, M. K. Serdula, et al. "Angular Stomatitis and Riboflavin Status Among Adolescent Bhutanese Refugees Living in Southeastern Nepal." American Journal of Clinical Nutrition 76 (August 2002): 430-435.
Larsson, C. L., and G. K. Johansson. "Dietary Intake and Nutritional Status of Young Vegans and Omnivores in Sweden." American Journal of Clinical Nutrition 76 (July 2002): 100-106.
McNulty, H., M. C. McKinley, B. Wilson, et al. "Impaired Functioning of Thermolabile Methylenetetrahydrofolate Reductase Is Dependent on Riboflavin Status: Implications for Riboflavin Requirements." American Journal of Clinical Nutrition 76 (August 2002): 436-441.
Shahar, S., K. Chee, and W. C. Wan Chik. "Food Intakes and Preferences of Hospitalised Geriatric Patients." BMC Geriatrics 2 (August 6, 2002): 3.
Silberstein, S. D., and P. J. Goadsby. "Migraine: Preventive Treatment." Cephalalgia 22 (September 2002): 491-512.
Wolf, G. "Three Vitamins Are Involved in Regulation of the Circadian Rhythm." Nutrition Reviews 60 (August 2002): 257-260.
Ziegler, R. G., S. J. Weinstein, and T. R. Fears. "Nutritional and Genetic Inefficiencies in One-Carbon Metabolism and Cervical Cancer Risk." Journal of Nutrition 132 (August 2002): 2345S-2349S.
ORGANIZATIONS
American Dietetic Association. 216 West Jackson Blvd., Chicago, IL 60606. (312) 899-0040. <www.eatright.org>.
Office of Dietary Supplements (ODS), National Institutes of Health. 6100 Executive Boulevard, Room 3B01, MSC 7517, Bethesda, MD 20892. (301) 435-2920. <www.ods.od.nih.gov>.
