Vitamin B-2 (Riboflavin)


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.


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.


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.


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.

Riboflavin, Vitamin B2 tablets

What are riboflavin tablets?

RIBOFLAVIN (Vitamin B2) is a naturally occurring vitamin found in milk, meat, eggs, nuts, enriched flour, and green vegetables. Riboflavin treats vitamin B2 deficiency. Riboflavin deficiency can cause itching, burning eyes; increased sensitivity of the eyes to light; mouth sores; and peeling of the skin on the nose and scrotum. Generic riboflavin tablets are available.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of the following conditions:
• an unusual or allergic reaction to B vitamins, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

How should I take this medicine?

Take riboflavin tablets by mouth. Follow the directions on the prescription label. Swallow the tablets with a glass of water.

What if I miss a dose?

If you miss a dose, skip that dose. Continue with your next scheduled dose.

What drug(s) may interact with riboflavin?

• propantheline

Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.

What should I watch for while taking riboflavin?

Make sure you have a proper diet. Taking riboflavin tablets does not replace the need for a balanced diet. Some foods that contain riboflavin include: milk, meat, eggs, nuts, enriched flour, and green vegetables.

What side effects may I notice from taking riboflavin?

The recommended daily allowance of riboflavin does not cause any serious side effects.
A minor side effect of riboflavin:

• bright yellow urine
This is no cause for alarm.

Where can I keep my medicine?

Keep out of the reach of children in a container that small children cannot open.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Keep container tightly closed. Throw away any unused medicine after the expiration date.



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American Dietetic Association. 216 West Jackson Blvd., Chicago, IL 60606. (312) 899-0040. .

Office of Dietary Supplements (ODS), National Institutes of Health. 6100 Executive Boulevard, Room 3B01, MSC 7517, Bethesda, MD 20892. (301) 435-2920. .

[Article by: Judith Turner; Rebecca J. Frey, PhD]

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