Riboflavin
Riboflavin
Definition
Riboflavin is a water-soluble vitamin that the body needs to remain healthy. Humans cannot make riboflavin, so they must get it from foods in their diet. Riboflavin is also called vitamin B2.
Riboflavin
| Age | Recommended Dietary Allowance (mg/day) |
| Children 0–6 mos. | 0.3 (AI) |
| Children 7–12 mos. | 0.4 |
| Children 1–3 yrs. | 0.5 |
| Children 4–8 yrs. | 0.6 |
| Children 9–13 yrs. | 0.9 |
| Boys 14–18 yrs. | 1.3 |
| Girls 14–18 yrs. | 1.0 |
| Men 19>yrs. | 1.3 |
| Women 19>yrs. | 1.1 |
| Pregnant women | 1.4 |
| Breastfeeding women | 1.6 |
| Food | Riboflavin (mg) |
| Yogurt, low fat, 1 cup | 0.52 |
| Milk, 2%, 1 cup | 0.40 |
| Tempeh, cooked, 4 oz. | 0.40 |
| Beef tenderloin, broiled, 4 oz. | 0.35 |
| Milk, nonfat, 1 cup | 0.34 |
| Egg, boiled, 1 large | 0.27 |
| Almonds, roasted, 1 oz. | 0.24 |
| Spinach, cooked, ½ cup | 0.21 |
| Chicken, dark meat, roasted, 3 oz. | 0.18 |
| Salmon, broiled, 3 oz. | 0.13 |
| Asparagus, cooked, ½ cup | 0.11 |
| Chicken, light meat, roasted, 3 oz. | 0.10 |
| Broccoli, steamed, ½ cup | 0.09 |
| Bread, white, enriched, 1 slice | 0.09 |
| Bread, whole wheat, 1 slice | 0.07 |
AI = Adequate Intake
mg = milligram
(Illustration by GGS Information Services/Thomson Gale.)
Purpose
Riboflavin has a broad range activities related to the conversion of nutrients into energy, making other vitamins and minerals available to the body, and acting as an antioxidant to remove of free radicals from cells.
Description
Without riboflavin, much of the food people eat could not be converted into energy. To produce energy, the body breaks down carbohydrates (starches and sugars) and fats into smaller units (glucose) that are then “burned” (oxidized) by cells to produce the energy they need to function. Riboflavin does not break down carbohydrates by itself. Instead, it joins with compounds called flavins that control the pathway that produces energy from food. Other vitamins such as B1 also are involved in this process. Riboflavin is especially important in supplying energy to muscles during physical activity and to the heart, which needs a continuous supply of energy.
When the body burns nutrients, free radicals are formed as a waste product of oxidation. Free radicals are highly reactive molecules that can damage cell membranes and DNA (genetic material). The damage that free radicals cause to cells is believed to play a role in the development of certain diseases, especially cancer . Riboflavin is an antioxidant. It binds to certain free radicals to neutralize them and remove them from the body so that they do not cause damage.
Riboflavin also plays a role in the way the body uses vitamin B6, niacin , folic acid, ironm and zinc . It helps convert vitamin B6 into its active form and is a necessary part of the chemical reactions that allow niacin to be used by the body. In the absence of riboflavin, less iron is absorbed from the intestines and the production of hemoglobin, the iron-containing molecule in red blood cells transports oxygen around the body, is depressed.
Normal riboflavin requirements
The United States Institute of Medicine (IOM) of the National Academy of Sciences has developed values called Dietary Reference Intakes (DRIs) for vitamins and minerals. The DRIs consist of three sets of numbers. The Recommended Dietary Allowance (RDA) defines the average daily amount of the nutrient needed to meet the health needs of 97-98% of the population. The Adequate Intake (AI) is an estimate set when there is not enough information to determine an RDA. The Tolerable Upper Intake Level (UL) is the average maximum amount that can be taken daily without risking negative side effects. The DRIs are calculated for children, adult men, adult women, pregnant women, and breastfeeding women.
The IOM has not set RDAs for riboflavin in children under one year old because of incomplete scientific information. Instead, it has set AI levels for this age group. No UL levels have been set for any age group because no negative (toxic) side effects have been found with large doses of riboflavin. RDAs for riboflavin measured in micrograms (mg).
The following are the RDAs and AIs for riboflavin for healthy individuals:
- children birth-6 months: AI 0.3 mg
- children 7-12 months: AI 0.4 mg
- children 1-3 years: RDA 0.5 mg
- children 4-8 years: RDA 0.6 mg
- children 9-13 years: RDA 0.9 mg
- boys 14-18 years: RDA 1.3 mg
KEY TERMS
Antioxidant— A molecule that prevents oxidation. In the body antioxidants attach to other molecules called free radicals and prevent the free radicals from causing damage to cell walls, DNA, and other parts of the cell.
Dietary supplement— A product, such as a vitamin, mineral, herb, amino acid, or enzyme, that is intended to be consumed in addition to an individual's diet with the expectation that it will improve health.
Enzyme— A protein that change the rate of a chemical reaction within the body without themselves being used up in the reaction.
Jaundice— A condition in which bilirubin, a waste product caused by the normal breakdown or red blood cells, builds up in the body faster than the liver can break it down. People with jaundice develop yellowish skin and the whites of their eyes become yellow. The condition can occur in new-borns and people with liver damage.
Vitamin— A nutrient that the body needs in small amounts to remain healthy but that the body cannot manufacture for itself and must acquire through diet.
Water-soluble vitamin— A vitamin that dissolves in water and can be removed from the body in urine.
- girls 14-18 years: RDA 1.0 mg
- women age 19 and older: RDA 1.1 mg
- men age 19 and older: RDA 1.3 mg
- pregnant women: RDA 1.4 mg
- breastfeeding women: RDA 1.6 mg
Sources of riboflavin
People need a continuous supply of riboflavin from their diet because very little riboflavin is stored in the body; any excess is excreted in urine. Almost all healthy people in the United States get enough riboflavin from their diet and do not need to take a riboflavin supplement. In the United States starting in 1943, riboflavin, along with thiamin and niacin, has been added to flour. Other good sources of riboflavin include brewer's yeast, whole grains, wheat germ, and dark green vegetables. Some breakfast cereals are also fortified with riboflavin.
Exposure to light breaks down riboflavin in foods. For example, milk stored in a clear container and left in sunlight for two hours will lose about half of its riboflavin content. Foods containing riboflavin should be stored in opaque containers to prevent breakdown of the vitamin by light. Consumers should select milk in paper cartons rather than glass bottles. Prolonged soaking or boiling also causes foods to lose riboflavin.
The following list gives the approximate riboflavin content for some common foods:
- spinach, cooked, 1/2 cup: 0.21 mg
- asparagus, cooked, 1/2 cup: 0.11 mg
- broccoli, steamed 1/2 cup: 0.09 mcg
- milk, 2% 1 cup 0.40 mg
- milk, nonfat 1 cup: 0.34 mg
- yogurt, low fat: 1 cup: 0.52 mg
- egg, boiled, 1 large: 0.27 mg
- almonds, roasted, 1 ounce: 0.24 mg
- salmon, broiled, 3 ounces: 0.13 mg
- chicken, light meat, roasted, 3 ounces: 0.10 mg
- chicken, dark meat, roasted, 3 ounces: 0.18 mg
- beef tenderloin, broiled, 4 ounces: 0.35 mg
- tempeh, cooked, 4 ounces 0.4 mg
- bread, whole wheat, 1 slice: 0.07 mg
- bread, white, enriched, 1 slice 0.09 mg
Riboflavin deficiency
Most healthy people in the United States get enough riboflavin in their diet because riboflavin is added to many common foods such as bread. Although dietary supplements containing large amounts of riboflavin do not appear to cause negative health effects, they also do not appear to improve health or athletic performance. Excess riboflavin is simply removed from the body in urine. Riboflavin deficiency, also called ariboflavinosis, rarely occurs alone. People who are riboflavin deficient usually also have deficiencies of other B vitamins. Those who are more likely to develop riboflavin deficiency include:
- newborns who receive light therapy for jaundice
- people with alcoholism
- people with anorexia nervosa (self starvation)
- people with celiac disease who cannot eat products containing gluten (e.g. wheat flour, bread, pasta)
- people who are lactose intolerant or who do not eat dairy products
- older, low income individuals who eat a poor diet of highly processed foods
Symptoms of riboflavin deficiency tend to be fairly mild and include sore throat and tongue, cracked skin around the mouth and lips, skin inflammation, and eye problems such as excessive sensitivity to light, burning eyes, and gritty-feeling eyes. Some researchers also believe that migraine headaches may be triggered by riboflavin deficiency. Inadequate levels of riboflavin may decrees the body's ability to use iron, zinc, folic acid, vitamin B3 and vitamin B12 .
Precautions
Riboflavin appears to be safe in high doses and also safe during pregnancy. Extended use of high-dose riboflavin supplements may cause an imbalance with other water-soluble vitamins, especially vitamin B1.
Interactions
Certain drugs appear to interfere with riboflavin's role in the chemical pathway that converts sugar to energy. These drugs include chlorpromazine and related anti-psychotic drugs, tricyclic antidepressants, quinacrine, a drug used to prevent malaria, and dox-orubicin (Adriamycin), a drug used in cancer chemotherapy. Long-term use of phenobarbitol seems to increase the rate of destruction of riboflavin by the liver.
Complications
No complications are expected from riboflavin use. However, for most people, taking riboflavin as a high-dose dietary supplement does not provide any benefits.
Parental concerns
Parents should be aware that the riboflavin stores in newborns treated with light therapy for jaundice are rapidly depleted. Parents of these newborns should discuss the need for a short-term riboflavin supplement with their pediatrician.
Resources
BOOKS
Berkson, Burt and Arthur J. Berkson. Basic Health Publications User's Guide to the B-complex Vitamins. Laguna Beach, CA: Basic Health Publications, 2006.
Gaby, Alan R., ed. A-Z Guide to Drug-Herb-Vitamin Interactions Revised and Expanded 2nd Edition: Improve Your Health and Avoid Side Effects When Using Common Medications and Natural Supplements Together. New York: Three Rivers Press, 2006.
Lieberman, Shari and Nancy Bruning. The Real Vitamin and Mineral Book: The Definitive Guide to Designing Your Personal Supplement Program, 4th ed. New York: Avery, 2007.
Pressman, Alan H. and Sheila Buff.The Complete Idiot's Guide to Vitamins and Minerals, 3rd ed. Indianapolis, IN: Alpha Books, 2007.
Rucker, Robert B., ed. Handbook of Vitamins. Boca Raton, FL: Taylor & Francis, 2007.
ORGANIZATIONS
American Dietetic Association. 120 South Riverside Plaza, Suite 2000, Chicago, Illinois 60606-6995. Telephone: (800) 877-1600. Website: <http://www.eatright.org>
Linus Pauling Institute. Oregon State University, 571 Weniger Hall, Corvallis, OR 97331-6512. Telephone: (541) 717-5075. Fax: (541) 737-5077. Website: <http://lpi.oregonstate.edu>
Office of Dietary Supplements, National Institutes of Health. 6100 Executive Blvd., Room 3B01, MSC 7517, Bethesda, MD 20892-7517 Telephone: (301)435-2920. Fax: (301)480-1845. Website: <http://dietary-supplements.info.nih.gov>
OTHER
Higdon, Jane. “Riboflavin.” Linus Pauling Institute-Oregon State University, September 19, 2002. <http://lpi.ore-gonstate.edu/infocenter/vitamins/riboflavin>
Harvard School of Public Health. “Vitamins.” Harvard University, November 10, 2006. <http://www.hsph.harvard.edu/nutritionsource/vitamins.html>
Maryland Medical Center Programs Center for Integrative Medicine. “Vitamin B2 (Riboflavin).” University of Maryland Medical Center, April 2002. <http://www.umm.edu/altmed/ConsSupplements/VitaminB2Riboflavincs.html>
Medline Plus. “Riboflavin (Vitamin B2).” U. S. National Library of Medicine, August 1, 2006. <http://www.nlm.nih/gov/medlineplus/druginfo/natural/patient-riboflavin.html>
Tsiouris, Nikolaos and Frederick H. Ziel. “Riboflavin Deficiency.” emedicine.com, November 15, 2002. <http://www.emedicine.com/med/topic2031.htm>
Tish Davidson, A.M.
Riboflavin
Riboflavin
Description
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.
Preparations
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 .
Resources
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>.
Judith Turner
Rebecca J. Frey, PhD
Riboflavin
Riboflavin
OVERVIEW
Riboflavin (REY-bo-FLAY-vin), commonly known as vitamin B2, is an orange-yellow crystalline solvent with a bitter taste. It is relatively stable when exposed to heat, but tends to decompose in the presence of light for extended periods of time. Riboflavin is used in the body for a variety of functions, including the metabolism of carbohydrates for the production of energy and the production of red blood cells.
KEY FACTS
OTHER NAMES:
Vitamin B2
FORMULA:
C17H20N4O6
ELEMENTS:
Carbon, hydrogen, nitrogen, oxygen
COMPOUND TYPE:
Organic
STATE:
Solid
MOLECULAR WEIGHT:
376.36 g/mol
MELTING POINT:
280°C (536°F)
BOILING POINT:
Not applicable; decomposes
SOLUBILITY:
Very slightly soluble in water and ethyl alcohol; very soluble in alkaline solvents, but resulting in decomposition
Riboflavin was first observed in 1879 by the English chemist Alexander Wynter Blyth (1844–1921) who noticed a compound in cow's milk that glowed with a yellow fluorescence when exposed to light. Blyth called the compound lachtochrome (lachto- = "milk" and -chrome = color), but was unable to determine its chemical composition or its chemical properties. In fact, it was not until the 1930s that the chemical nature of the compound was determined. The Swiss chemist Paul Karrer (1889–1971) and the Austrian-German chemist Richard Kuhn (1900–1967) independently determined the chemical structure of riboflavin and first synthesized the compound. The name riboflavin is derived from the fact that the vitamin was first found in association with the sugar ribose.
HOW IT IS MADE
Plants and microorganisms synthesize riboflavin naturally. Some foods rich in riboflavin are brewer's yeast, dark green vegetables, mushrooms, legumes, nuts, milk and other dairy products, sweet potatoes, and pumpkins. Bacteria that live in the human digestive tract are also able to synthesize some riboflavin, but not enough to meet the body's requirement for the vitamin.
Riboflavin is produced synthetically using either the genetically-modified bacterium Bacillus subtilis or a fungus called Ashbya gossifyii. The bacteria or fungus are cultured in a large vat that has been seeded with small amounts of riboflavin. Over time, the organisms generate large quantities of riboflavin until some desired amount of the compound has been produced. The vat is then heated to a temperature sufficient to kill the bacteria or fungi, leaving crystalline riboflavin behind. The riboflavin is then separated and purified.
Interesting Facts
- The human body cannot store riboflavin, so it is excreted in the urine. For this reason, it is not dangerous to consume large doses of riboflavin, although the consumption of large amounts of the vitamin serves no biological purpose.
- Since riboflavin does not dissolve in water, it must be converted to a water soluble form, such as riboflavin-5-phosphate, for use as a food additive.
- The recommended daily dose of riboflavin for adults is 1.6 milligrams for men, 1.2 milligrams for women, 0.6 milligrams for children age four to eight, 0.9 milligrams for children age nine to thirteen, and 1.3 milligrams for teenagers.
COMMON USES AND POTENTIAL HAZARDS
The human body needs riboflavin to use oxygen efficiently in the metabolism of amino acids, fatty acids, and carbohydrates. The vitamin is involved in the synthesis of niacin (another B vitamin), it activates vitamin B6, and it helps the adrenal gland to produce hormones. It helps the body make antibodies to fight disease and infection, regulates the thyroid gland, and is important in maintaining healthy hair, nails, and skin. Riboflavin is especially important during periods of rapid growth because it is involved in the formation and growth of cells, especially red blood cells.
In combination with vitamin A, riboflavin helps maintain the mucous membranes that line the digestive tract. Pregnant women need riboflavin to help the fetus grow and develop. The vitamin is also essential for eye health. Some medical professionals recommend riboflavin for the treatment of eye disorders, such as cataracts, sensitivity to bright light, and bloodshot, burning, or itching eyes. Doctors have begun experimenting with the use of riboflavin to treat migraine headaches.
In spite of its many important functions in the body, riboflavin deficiencies do not lead to serious medical problems or death. They may result in a delayed healing of wounds or relatively minor medical conditions such as cheilosis (a reddening and soreness in the corners of the lips), angular stomatitis (cracking of the skin at the corner of the lips), dermatitis (an oily skin disorder), glossitis (a swollen, reddened tongue), and cracking around the nose. In all such cases, however, a riboflavin deficiency by itself is almost never the cause of the problem; instead, deficiencies of other vitamins in the B group are also involved.
Words to Know
- CARBOHYDRATE
- A group of sugars and starches produced by plants and used as food.
- JAUNDICE
- A disease caused by malfunction of the liver in which the skin and eyes become yellow.
- LEGUME
- A member of the pea family of plants, which includes peas and beans.
- METABOLISM
- The process that includes all of the chemical reactions that occur in cells by which fats, carbohydrates, and other compounds are broken down to produce energy and the compounds needed to build new cells and tissues.
- MUCOUS MEMBRANES
- Tissues that line the moist inner lining of the digestive, respiratory, urinary and reproductive systems.
- SOLVENT
- A substance that is able to dissolve one or more other substances.
- SYNTHESIS
- A chemical reaction in which some desired chemical product is made from simple beginning chemicals, or reactants.
Riboflavin deficiencies are very rarely seen in the United States because the vast majority of people consume a diet that contains adequate amounts of the vitamin. Individuals most likely to suffer from riboflavin deficiency problems are those with anorexia (a condition in which people refuse to eat adequate amounts of food), older people with poor diets, alcoholics (because alcohol impairs a person's ability to absorb and use the vitamin), and newborn babies being treated for jaundice by exposure to ultraviolet light (because light destroys riboflavin).
FOR FURTHER INFORMATION
"Food Safety: From the Farm to the Fork." European Commission Web Site. http://europa.eu.int/comm/food/fs/sc/scf/out18_en.html (accessed on November 3, 2005).
"Riboflavin." Linus Pauling Institute, Micronutrient Information. http://lpi.oregonstate.edu/infocenter/vitamins/riboflavin/ (accessed on November 3, 2005).
"Riboflavin." MedlinePlus. http://www.nlm.nih.gov/medlineplus/ency/article/002411.htm (accessed on November 3, 2005).
"Vitamin B2 (Riboflavin)." Herb & Supplement Encyclopedia. http://www.florahealth.com/flora/home/canada/healthinformation/encyclopedias/VitaminB2.asp (accessed on November 3, 2005).
Riboflavin
Riboflavin
Description
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.
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 during 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 protection 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.
Preparations
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.
Risk factors for deficiency
Riboflavin deficiency is uncommon, but some populations may need more than the RDA in order to maintain good health. Vegans, and others who do not use dairy products, would do well to take a balanced B vitamin supplement. 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.
KEY TERMS
Antioxidant —Any one of a group of substances that function to destroy cell-damaging free radicals in the body.
Migraine —A very severe headache, often accompanied by nausea and vomiting. It is usually experienced on one side of the head, and may be preceded by visual symptoms.
Neuropathy —Abnormality of the nerves, which may be manifested as numbness, tingling, or weakness of the affected area.
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.
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. 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.
Resources
BOOKS
Bratman, Steven, and David Kroll. Natural Health Bible. Prima Publishing, 1999.
Feinstein, Alice. Prevention's Healing with Vitamins. Emmaus, PA: 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.
Judith Turner
Riboflavin
Riboflavin
Description
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.
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 10 years. Women need 1.3 mg from 11-50 years, and 1.2 mg thereafter. Slightly more is required during 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 protection 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.
Preparations
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.
Risk factors for deficiency
Riboflavin deficiency is uncommon, but some populations may need more than the RDA in order to maintain good health. Vegans and others who do not use dairy products would do well to take a balanced B vitamin supplement. 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. 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.
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. 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.
KEY TERMS
Antioxidant— Any one of a group of substances that function to destroy cell-damaging free radicals in the body.
Migraine— A very severe headache, often accompanied by nausea and vomiting. It is usually experienced on one side of the head, and may be preceded by visual symptoms.
Neuropathy— Abnormality of the nerves, which may be manifested as numbness, tingling, or weakness of the affected area.
Resources
BOOKS
Bratman, Steven, and David Kroll. Natural Health Bible. Prima Publishing, 1999.
Feinstein, Alice. Prevention's Healing with Vitamins. Emmaus, PA: 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.
Riboflavin
Riboflavin
Riboflavin, also known as vitamin B2, gets its name from its sugar alcohol (ribitol), and from its yellow color and its fluorescence under UV light (flavin comes from the Latin word for yellow). Its systematic names are 7,8-dimethyl-10-(D-ribo-2,3,4,5-tetrahydroxypentyl)isoalloxazine and 7,8-dimethyl-10-ribitylisoalloxazine; its formula is C17H20N4O6. Riboflavin has a molar mass of 376.37 grams (13.3 ounces). It is heat-stabile but easily degraded by light. Riboflavin was referred to as vitamin G in the early part of the twentieth century because it was recognized as a dietary factor needed for growth. Riboflavin was first isolated in 1879, and its chemical structure was determined in 1933.
As determined by the National Research Council of the National Academy of Sciences, the recommended daily allowance (RDA) of riboflavin for adults is about 1.5 milligrams (5.3 × 10−5 ounces). The amount required by an individual varies with factors such as age, gender, and amount of physical activity. Riboflavin is found in many foods, such as eggs, nuts, grains, dairy products, organ meats, and dark green vegetables. Overall, riboflavin content in the body can be estimated by measuring the activity of glutathione reductase (a riboflavin-containing enzyme) in red blood cells. No one has been known to ever die of riboflavin deficiency, but it can occur as a consequence of malnourishment, intake of certain medication, chronic diarrhea, or alcoholism. The first symptoms of riboflavin deficiency are often light sensitivity, blurred vision, and bloodshot eyes. Other symptoms are skin and mucous membranes lesions. Because riboflavin is water-soluble and easily excreted , toxicity resulting from excess intake is not considered a health problem.
Riboflavin is important biochemically because it is vital for proper utilization of carbohydrates, fats, and proteins as energy sources. It is a component
of two coenzymes, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). (Coenzymes are molecules that must be added to certain polypeptides to make them functional enzymes.) In general, FAD and FMN, when tightly bound to specific enzymes, easily lose or gain one or two electrons, or hydrogen atoms, and so drive oxidation /reduction reactions. In the 1930s, Warburg and Christian studied "the old yellow enzyme," a riboflavin-requiring enzyme, and laid the groundwork for our current understanding of cyclic oxidation-reduction reactions in electron transport systems vital to cell respiration. In addition to their role in electron transport chains, FAD- and FMN-requiring enzymes catalyze reactions that are part of a wide array of metabolic pathways.
see also Coenzyme.
Sharron W. Smith
Bibliography
Garrett, Reginald H., and Grisham, Charles M. (2002). Principles of Biochemistry: With a Human Focus. Fort Worth, TX: Harcourt College Publishers.
Robinson, Corinne H.; Lawler, Marilyn R.; Chenoweth, Wanda L.; et al. (1986). Normal and Therapeutic Nutrition, 17th edition. New York: Macmillan.
Internet Resources
Nutrition.org. Information available from <http://www.nutrition.org>.
riboflavin
riboflavin
ri·bo·fla·vin / ˌrībəˈflāvin; ˈrībəˌflā-/ • n. Biochem. a yellow vitamin of the B complex that is essential for metabolic energy production. It is present in many foods, esp. milk, liver, eggs, and green vegetables, and is also synthesized by the intestinal flora. Also called vitamin B2.