Vitamin B2, also called riboflavin, is one of 8 B vitamins. All B vitamins help the body to convert food (carbohydrates) into fuel (glucose), which is "burned" to produce energy. These B vitamins, often referred to as B complex vitamins, also help the body metabolize fats and protein. B complex vitamins are necessary for healthy skin, hair, eyes, and liver. They also help the nervous system function properly.
All the B vitamins are water-soluble, meaning that the body does not store them.
In addition to producing energy for the body, riboflavin also works as an antioxidant by fighting damaging particles in the body known as free radicals. Free radicals can damage cells and DNA, and may contribute to the aging process, as well as the development of a number of health conditions, such as heart disease and cancer. Antioxidants such as riboflavin can fight free radicals and may reduce or help prevent some of the damage they cause.
Riboflavin is also needed to help the body change vitamin B6 and folate into forms it can use. It is also important for body growth and red blood cell production.
Most healthy people who eat a well-balanced diet get enough riboflavin. However, elderly people and alcoholics may be at risk for riboflavin deficiency because of poor diet. Symptoms of riboflavin deficiency include fatigue; slowed growth; digestive problems; cracks and sores around the corners of the mouth; swollen magenta-colored tongue; eye fatigue; swelling and soreness of the throat; and sensitivity to light.
Vitamin B2, along with other nutrients, is important for normal vision. Some early evidence shows that riboflavin might help prevent cataracts -- damage to the lens of the eye, which can lead to cloudy vision. In one double-blind, placebo-controlled study, people who took a niacin and riboflavin supplement had fewer cataracts than people who took other vitamins and nutrients. However, researchers don't know whether that was due to riboflavin, niacin, or the combination of the two. And levels above 10 mg per day of riboflavin can actually promote damage to the eye from the sun. More research is needed to see if riboflavin can really help in preventing cataracts.
Several studies suggest that people who get migraines may reduce how often they get migraines and how long they last by taking riboflavin. One double-blind, placebo-controlled study showed that taking 400 mg of riboflavin a day cut the number of migraine attacks in half. The study did not compare riboflavin to conventional medications used to prevent migraines, however, so more research is needed.
The best sources of riboflavin include brewer's yeast, almonds, organ meats, whole grains, wheat germ, wild rice, mushrooms, soybeans, milk, yogurt, eggs, broccoli, Brussels sprouts, and spinach. Flours and cereals are often fortified with riboflavin.
Riboflavin is destroyed by light, so food should be stored away from light to protect its riboflavin content. While riboflavin is not destroyed by heat, it can be lost in water when foods are boiled or soaked. During cooking, roasting, and steaming preserves more riboflavin than frying or scalding.
Riboflavin is generally included in multivitamins and B-complex vitamins, and comes separately in 25-, 50-, and 100-mg tablets.
How to Take It
As with all medicines, check with a health care provider before giving riboflavin supplements to a child.
Daily recommendations for dietary riboflavin are listed below.
- Infants birth - 6 months: 0.3 mg (adequate intake)
- Infants 7 - 12 months: 0.4 mg (adequate intake)
- Children 1 - 3 years: 0.5 mg (RDA)
- Children 4 - 8 years: 0.6 mg (RDA)
- Children 9 - 13 years: 0.9 mg (RDA)
- Boys 14 - 18 years: 1.3 mg (RDA)
- Girls 14 - 18 years: 1 mg (RDA)
- Men 19 years and older: 1.3 mg (RDA)
- Women 19 years and older: 1.1 mg (RDA)
- Pregnant women: 1.4 mg (RDA)
- Breastfeeding women: 1.6 mg (RDA)
Riboflavin is best absorbed when taken between meals.
People who do not eat a balanced diet every day may benefit from taking a multivitamin and mineral complex.
Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.
Riboflavin is generally considered safe, even at high doses. However, because doses above 10 mg per day may cause eye damage from the sun, people who take high doses should wear sunglasses that protect their eyes from ultraviolet light.
Riboflavin does not seem to cause any serious side effects. Very high doses may cause itching, numbness, burning or prickling sensations, yellow or orange urine, and sensitivity to light.
Taking any one of the B vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, you may want to take a B complex vitamin, which includes all the B vitamins.
If you are currently being treated with any of the following medications, you should not use vitamin B2 supplements without first talking to your health care provider.
Anticholinergic Drugs -- used to treat a variety of conditions, including gastrointestinal spasms, asthma, depression, and motion sickness. These drugs may make it hard for the body to absorb riboflavin.
Tetracycline -- Riboflavin interferes with the absorption and effectiveness of tetracycline, an antibiotic. All vitamin B complex supplements act in this way. You should take riboflavin at a different time during the day from when you take tetracycline.
Tricyclic Antidepressants -- Tricyclic antidepressants may reduce levels of riboflavin in the body. They include:
- Imipramine (Tofranil)
- Desimpramine (Norpramin)
- Amitriptyline (Elavil)
- Nortriptyline (Pamelor)
Antipsychotic Medications -- Antipsychotic medications called phenothiazines (such as chlorpromazine or Thorazine) may lower riboflavin levels.
Doxorubicin -- Riboflavin interferes with doxorubicin, a medication used for the treatment of certain cancers. Also, doxorubicin may deplete levels of riboflavin in the body. Your doctor will let you know whether you need to take a riboflavin supplement or not.
Methotrexate -- Methotrexate, a medication used to treat cancer and autoimmune diseases such as rheumatoid arthritis, can interfere with how the body uses riboflavin.
Phenytoin -- Phenytoin (Dilantin), a medication used to control seizures, may affect riboflavin levels in the body.
Probenecid -- This medication used for gout may decrease the absorption of riboflavin from the digestive tract and increase how much is lost in the urine.
Thiazide Diuretics (water pills) -- Diuretics that belong to a class known as thiazides, such as hydrochlorothiazide, may cause you to lose more riboflavin in your urine.
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