Riboflavin (Vitamin B2) Uses, Benefits, Dosages, Side Effects & Interactions

Riboflavin (Vitamin B2) is essential for energy metabolism and cellular respiration. It plays important roles in the body as a coenzyme involved in various physiological processes.

Vitamin B2 is involved in the metabolism of fat and protein, red blood cell formation, the synthesis of neurotransmitters, brain health, hearing and vision.

Use of riboflavin supplements may improve migraine headaches, cataracts, and improve elevated homocysteine levels in the body.

If you are deficient in riboflavin, you may experience a condition called ariboflavinosis which can result in skin problems, inflammation, eye problems, impaired iron absorption and anemia. In pregnant women, deficiency can result in birth defects.

This vitamin is found naturally in milk, cheese, eggs, leafy greens, legumes, almonds and certain mushrooms. Flour sold in the United States is enriched with Vitamin B2 to prevent deficiency.

This article will review what riboflavin is, how it works in the body, its purported health benefits, recommended dosages, side effects, and potential drug interactions.

Riboflavin

Vitamin B2 Supplement

Energy

Red Blood Cells

Brain Function

How It Works:

• Important for red blood cell production
• Supports nervous system function
• Involved in cellular energy metabolism

Dosage:

Between 100 - 400 mg per day

Safety:

Rated Likely Safe

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What is Riboflavin?

Riboflavin (vitamin B2) is one of the eight B-complex vitamins.

Like other B vitamins, it is used in the body to convert carbohydrates from food into usable energy. B vitamins also help the body to break down and use fats and proteins.

Together, all members of the B-complex family of vitamins are important for maintaining the health of the central nervous system (CNS), immune system, cardiovascular system, liver, eyes, skin, hair, and nails.

Active forms of this vitamin in the body include flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). These compounds are cofactors for many different flavoprotein enzyme reactions.

In research, riboflavin has been seen to demonstrate significant antioxidant effects, meaning it helps the body to resist and repair damage from free radical molecules. Elevated free radicals are associated with increased risk of some diseases as well as premature aging. [1]

The body also needs riboflavin to convert pyridoxine (vitamin B6) and folic acid (vitamin B9) into usable forms. This micronutrient is also needed in fetal growth and in red blood cell production (erythropoiesis). [2]

Many vitamins are fat-soluble, which means that they can be stored in the body’s fat cells to prevent a deficiency. B-complex vitamins like riboflavin are water-soluble; meaning they do not dissolve in lipids or alcohol.

Because of this, riboflavin is not stored in the body’s adipocytes (fat cells). [1] The only B vitamin that is stored in any substantial amounts in the body is vitamin B12 (cobalamin).

That means that we must consistently obtain this important nutrient from the foods we eat, or by using dietary supplements that contain it.

How Does Riboflavin Work Inside the Body?

Riboflavin is used by the body as a precursor to two important enzymes: FAD (flavin adenine dinucleotide) and FMN (flavin mononucleotide). [2]

According to PubChem, “Riboflavin occurs in the free form only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as flavin mononucleotide and flavin-adenine dinucleotide.” [2]

PubChem also reports that these coenzymes are vital for the following processes in the body:

• Normal tissue respiration
• Pyridoxine [vitamin B6] activation
• Tryptophan to niacin [vitamin B3] conversion
• Fat, carbohydrate, and protein metabolism
• Glutathione reductase mediated detoxification [2]

This vitamin is critical for regulating growth and reproduction, producing antibodies, and forming red blood cells. It is also needed for regulating thyroid gland activity and general good health. [2]

Riboflavin deficiency is known to increase the risk of certain eye disorders. Population studies have found that a higher dietary intake of this nutrient is associated with a decreased risk of age-related lens opacification (cataracts). [3]

The Linus Pauling Institute (LPI) states that oxidative stress can cause damage to the eye lens, resulting in opacification or clouding. This can lead to cataracts in elderly individuals.

LPI says that some observational studies suggest a link between increasing riboflavin intake and the prevention of cataracts. However, interventional studies (also known as clinical trials) are necessary to assess whether this vitamin is effective or not. [4]

Vitamin B2 might improve certain hematological responses to iron supplementation in people with anemia. However, this is only reported in subjects with some degree of riboflavin deficiency. [3]

Riboflavin is also being researched for migraine headache prevention in both children and adults. Clinical research in adults has shown that supplementing with this compound decreases the frequency, severity, and duration of migraine attacks. [4]

Research in children using a lower dosage has not shown a significant improvement in migraine frequency. Trials using the same dosages as adult studies have not been conducted yet.

Riboflavin continues to be explored clinically as an adjunct therapy for eye disorders, migraines, and various types of cancer. [4]

Uses for Riboflavin

The Natural Medicines Comprehensive Database (NMCD) reports that people use riboflavin supplements orally for:

• Vitamin B2 deficiency
• Boosting immune system function
• Cervical cancer
• Congenital methemoglobinemia (abnormal hemoglobin variations)
• Increasing athletic performance
• Increasing energy levels
• Maintaining healthy hair, skin, mucous membranes, and nails
• Memory loss including Alzheimer’s disease
• Migraine headaches
• Multiple acylcoenzyme A dehydrogenase deficiency
• Promoting healthy reproductive function
• Red blood cell aplasia (abnormal function/formation) [3]

Riboflavin is also used orally for anti-aging, carpal tunnel syndrome, burning feet syndrome, acne, canker sores, burns, and muscle cramps. It is also used orally or sometimes as eye drops for eye fatigue, cataracts, and glaucoma. [3]

This vitamin has also been used orally for sickle cell anemia, alcoholism, liver disease, and lactic acidosis induced by nucleoside analog reverse transcriptase inhibitor (NRTI) drugs. [3]

Riboflavin Health Benefits

The NMCD has rated riboflavin as Effective for preventing and treating ariboflavinosis (riboflavin deficiency).

According to the NMCD, “Taking oral riboflavin 0.95-5 mg for 5-7 days weekly for up to one year prevents riboflavin deficiency and improves ariboflavinosis in adults and children.” [3]

The NMCD has rated riboflavin as Possibly Effective for migraine headache, cataracts, and hyperhomocysteinemia (elevated homocysteine levels).

Promising results have come from some preliminary trials done using riboflavin for cervical cancer, esophageal cancer, lactic acidosis, and sickle cell disease. However more research is still needed to determine the therapeutic efficacy for these and other uses.

The FDA has approved a high-dose vitamin B2 product as a prescription medication, typically administered for treatment of migraines. It has not approved the use of this dietary supplement as a drug for the prevention or treatment of other medical conditions.

Migraine Headaches

In multiple research studies, using riboflavin in high doses of 400 mg/day for up to 3 months seems to significantly decrease the frequency of migraine attacks compared to pre-treatment. [3]

Other studies have shown that this supplement can promote a significant improvement in the frequency, severity, and duration of migraines compared to a placebo.

The researchers from one study suggested that riboflavin may be as effective at reducing migraine frequency as beta blocker drugs like Lopressor (metoprolol) and Zebeta (bisoprolol). [3]

Research using this supplement in conjunction with other compounds is limited and contradictory.

Taking 400 mg vitamin B2, 300 mg magnesium, and 100 mg feverfew does not seem to reduce migraine headache frequency, relative to placebo. 3]

The results of this study are confounded as the placebo was an active placebo that in fact contained 25 mg of riboflavin.

In another study, patients were given either a placebo or a combination product containing 400 mg vitamin B2 and 600 mg magnesium, 150 mg coenzyme Q10, as well as other vitamins and minerals.

It was seen that compared to the placebo group, there was not a reduction in the number of migraine days in the treatment group. However, patients did report improved pain and quality of life in the riboflavin group.

In research studies, a 200 mg/day dose of vitamin B2 does not seem to affect the frequency of migraine headaches in children. [3]

Research studies administering the 400 mg/day dosages used in adults trials have not yet been conducted.

The results yielded so far have been promising. More research is necessary to fully determine the therapeutic efficacy of riboflavin for migraine headaches. [3]

Cataracts and Eye Health

High dietary intake of riboflavin is associated with a lower risk for developing nuclear cataracts. It also seems to reduce the progression of eye lens opacification due to aging. [3]

In one study, taking 3 mg vitamin B2 along with 40 mg niacin (vitamin B3) lowered the risk for developing cataracts relative to a placebo. [3]

More research is still needed to understand how riboflavin protects eye health and whether it is therapeutically effective for preventing or treating cataracts. [3]

Hyperhomocysteinemia

Homocysteine is a nonprotein alpha amino acid that is very similar in molecular structure to the amino acid cysteine.

High levels of homocysteine in the blood is called hyperhomocysteinemia. It can cause damage to the endothelial cells that line blood vessels, which can subsequently cause atherogenesis (formation of arterial plaques) and ischemic (restricted blood supply) injury.

One research study showed that taking 1.6 mg vitamin B2 daily for 12 weeks reduced homocysteine levels by between 22-44%.

However, these effects are only seen in patients with the TT genotype for the methylenetetrahydrofolate reductase (MTHFR) enzyme. Use does not seem to reduce homocysteine levels in those with CC or CT genotypes. [3]

NMCD reports, “In individuals with hyperhomocysteinemia due to the use of antiepileptic drugs, taking riboflavin 75 mg daily, in combination with folic acid 0.4 mg plus pyridoxine 120mg, reduces plasma total homocysteine by 26% compared to pretreatment.” [3]

At this time it is still not known if elevated homocysteine levels are a cause of vascular disease, or rather an effect of existing disease. It has not been determined at this point if lowering homocysteine levels results in a reduction of cardiovascular disease incidence or risk.

More research is needed to determine the relationship between homocysteine and vascular disease, as well as the therapeutic efficacy of vitamin B2 for hyperhomocysteinemia.

Riboflavin Deficiency

Ariboflavinosis is very rare in the United States and Canada, and most other developed countries.

A deficiency can be caused by inadequate intake, excessive loss of this vitamin from the body, malabsorption, increased physiological demands, endocrine abnormalities, and some diseases. [3]

The National Institutes of Health (NIH) states that the common signs and symptoms of a deficiency can include:

• Skin disorders
• Hyperemia (excess blood in vessels supplying an organ or part of the body)
• Edema of the mouth and throat
• Angular stomatitis (lesions at the corners of the mouth)
• Cheilosis (swollen, cracked lips)
• Hair loss
• Reproductive problems
• Sore throat
• Itchy and red eyes
• Degeneration of the liver and nervous system [5]

The LPI describes additional symptoms such as the formation of blood vessels in the clear covering of the eye, also known as vascularization of the cornea.

A deficiency can also cause a decreased red blood cell count known as normochromic normocytic anemia. In this condition, existing red blood cells contain normal levels of hemoglobin and are normally sized. [4]

If left unaddressed, vitamin B2 deficiency can lead to anemia, cataracts, and other health problems. Deficiency is usually easily reversed with increased intake of this vitamin through foods or supplements. [5]

Vegetarian athletes, pregnant women, breastfeeding mothers, infants, and those who consume little bovine milk are likely to develop ariboflavinosis than other groups. [5]

Alcohol inhibits intestinal absorption of vitamin B2. [3] Alcoholics are at a higher risk of deficiency.

Riboflavin Food Sources

PubChem reports some riboflavin-rich food sources include yeast, malted barley, eggs, and cow milk. Other good sources include:

• Dark-green leafy vegetables
• Fortified cereals and breads
• Liver, kidney, heart, and other organ meats
• Mushrooms
• Soybeans
• Wheat germ
• Wild rice
• Yogurt [2]

According to PubChem, this vitamin can be found in a number of enriched products. Some examples of foods fortified with riboflavin include baby foods, breakfast cereals, sauces, processed cheese, fruit drinks and certain milk products. [2]

Riboflavin is destroyed by light and heat. Roasting and steaming preserves more of this vitamin in foods compared to boiling, frying, or scalding. [1]

Riboflavin Supplements

The University of Maryland Medical Center (UMM) states that riboflavin is incorporated into general multivitamin products and B-complex multivitamin formulations. [1]

According to NMCD, “Well-known standardization for riboflavin is lacking. The most common forms of riboflavin available in supplements are riboflavin and riboflavin 5′-monophosphate.” [3]

It is available as a sole ingredient in 25 mg, 50 mg, and 100 mg tablets. It is normally taken along with other B vitamins. [1]

In many B-complex multivitamins, riboflavin is provided at a dosage of between 20-75 mg per serving.

The NMCD reports that there are thousands of different dietary supplement products that contain vitamin B2. With so many available products, it is important to select high-quality supplements made by reputable manufacturers. [3]

When possible, look for riboflavin supplements that are organic and non-GMO. Choose certified toxin-free products from trusted sources.

Heat, light, and air can destroy riboflavin content in products. Store supplements in dark, airtight containers in cool, low-lit locations. [2]

Riboflavin Dosage Guidelines

Riboflavin RDAs (recommended daily allowances) have been set by the US FDA in the following amounts per age group:

• 0.3 mg for those 0-6 months of age
• 0.4mg for those 7-12 months old
• 0.5mg for those 1-3 years old
• 0.6mg for those 4-8 years old
• 0.9mg for those 9-13 years old
• 1mg for female adolescents (14-18 years old)
• 1.3mg for male adolescents (14-18 years old)
• 1.1mg for female adults (older than 18 years)
• 1.3mg for male adults (older than 18 years)
• 1.4mg for pregnant women (any age)
• 1.6mg for breastfeeding women (any age)

When used as a dietary supplement, dosages are typically higher than RDA values. Most single ingredient riboflavin supplements provide between 25-100 mg of this vitamin.

The NMCD reports the following vitamin B2 dosages that have been used in some human research:

• 80 mg weekly, for up to 20 months, for cancer prevention
• 25 mg/day for improving cognitive function
• 25 mg/day, for up to 12 weeks, for pre-eclampsia
• 15 mg/day, for unknown duration, for pre-eclampsia
• 5 mg/day, 5 days per week, for 1 year, for ariboflavinosis
• 5 mg/day, for up to 9 years for cancer prevention
• 5 mg, twice daily, for 8 weeks, for anemia
• 1.6 mg/day, for 12 weeks for hyperhomocysteinemia [2]

It is recommended to speak with your doctor to help determine the best riboflavin dosage for your needs.

Riboflavin Safety and Side Effects

The Natural Medicines Comprehensive Database rates Vitamin B2 as Likely Safe when used orally in appropriate dosage.

It is also rated as Likely Safe when used orally at recommended RDA values by pregnant and lactating women. In these groups it is rated as Possibly Safe when used in appropriately higher dosages, short-term when necessary.

The NIH states that riboflavin doses many times over the RDA have caused no reported adverse effects.

Daily 400 mg doses for 3 months caused no observable toxicity in research studies. Because of this, the FDA has not set an UL (upper tolerable limit) for riboflavin. [5]

NMCD says that humans have a limited capacity to absorb this supplement when administered orally. It is also rapidly excreted from the body, which minimizes the risk of potential harm from taking an overdose.

However, if you use too much, you may experience adverse reactions including diarrhea, polyuria (high urine production), and chromaturia (abnormal urine color). [3]

Secondary sources say that that very high doses of vitamin B2 can cause diarrhea, yellow urine, burning, itching, prickling, and numbness. [2]

Riboflavin Drug Interactions

Use of this supplement may cause interactions with certain drugs. Some medications can also deplete levels of this vitamin in the body or impair its absorption from the gut.

Anticholinergic drugs, like propantheline for instance, can decrease absorption of supplemental riboflavin. [2]

Taking vitamin B2 in high doses might interfere with tetracycline antibiotics like demeclocycline (Declomycin), doxycycline (Vibramycin), and minocycline (Minocin). [3]

TCAs (tricyclic antidepressants) have similar molecular structures to riboflavin, and they may interfere with its conversion to its active form: FAD (flavin adenine dinucleotide). [3]

Blond psyllium can reduce absorption of supplemental vitamin B2 in healthy women. [3]

Boric acid can form a complex with riboflavin, increasing its solubility in water. This can significantly increase urinary excretion of the vitamin within a 24-48-hour period after ingestion. [4]

The NMCD states, that taking 400 mcg of folic acid per day can exacerbate or worsen a riboflavin deficiency in people who have the TT genotype for methylenetetrahydrofolate reductase (MTHFR). [3]

Oral contraceptives might interfere with riboflavin absorption and/or its conversion to active coenzymes. This is most evident in women with inadequate dietary intake of riboflavin. [4]

Vitamin B2 supplements might interfere with laboratory tests that measure acetoacetate decarboxylase, catecholamines, colorimeters, drugs of abuse, diagnex blue excretion, and plasma and urine fluorometric urobilinogen. [3]

Consult with your doctor first before taking this supplement if you have hepatitis, liver cirrhosis or biliary obstruction.

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