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

Vitamin B2 (riboflavin) is a water-soluble essential nutrient that is important for regulating cellular growth, reproduction, energy metabolism and for the process of cellular respiration.

In the human body, Vitamin B2 is converted into two primary enzymes that are required to synthesize red blood cells, produce immune system antibodies and to break down fats, carbohydrates and proteins.

If you do not have adequate levels of this B vitamin in your diet, it could result in problems with vision, skin, nails and hair growth, impaired cognitive function, low energy levels or inflammation.

Most people are able to obtain adequate amounts of this nutrient from their diet to avoid a deficiency. However, there may be cases where supplementing with additional sources of Vitamin B2 may have additive health benefits.

This supplement has been used as a prophylactic for the prevention of migraine headaches. It is also used as an anti-aging supplement, to promote detoxification, reduce homocysteine levels and to support vision health.

This article will discuss how vitamin B2 works in the body, common uses, health benefits, deficiency issues, food and supplement sources, safety and side effects, and possible 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 Vitamin B2?

Vitamin B2 is a B-complex vitamin that is typically found in supplements as riboflavin. In dietary supplements it may also exist in the form of riboflavin 5′-phosphate sodium.

Many plants and animals are able to produce this important micronutrient endogenously, but not humans. Vitamin B2 is essential in humans, meaning that we have to obtain it from foods or supplements.

Like other B-complex members, riboflavin is used in the production of the body’s main cellular fuel, adenosine triphosphate (ATP). It is also important for facilitating healthy adrenal function, and for supporting the function of the nervous system.

In the human body, it is found primarily as a component of flavocoenzymes, such as the coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN).

These coenzymes are then used in flavoproteins, which have a wide range of functions in the body.

Vitamin B2 is needed for proper cell function and growth, and for activating other nutrients, especially other B-complex vitamins. [1]

Emerging evidence from clinical trials suggests that supplementing with riboflavin has antioxidant effects. It has been shown to inhibit cellular damage from free radicals and may support the repair of this damage. [2]

Vitamin B2 is thought to have an important role in protecting the eyes from oxidative stress. Free radical damage can cause opacification of the cornea, resulting in the development of cataracts.

Cataracts are eye disorders where the lens becomes progressively opaque or clouded over. This often leads to vision impairment, and total blindness in some cases.

According to Dr. Andrew Weil, “Common diseases and illnesses that may be prevented or alleviated via riboflavin supplementation include neonatal jaundice, anemia, anorexia/bulimia, cataracts, cognitive function (thinking and memory), depression, and migraines.” [3]

How Does Vitamin B2 Work in the Body?

The University of Maryland Medical Center (UMM) states that riboflavin is commonly found in the body as a coenzyme, meaning that protein-based enzymes need it to function.

T the main role of vitamin B2 in humans is to produce two cofactors that are necessary for numerous different enzymes to function normally. These two cofactors are flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). [2]

FAD and FMN are used in many flavoprotein enzymatic reactions. They function as electron carriers in redox (oxidation-reduction) reactions involved in energy metabolism.

These enzymes are particularly important for redox chemistry involving fatty acid oxidation. [2]

According to Dr. Josh Axe, vitamin B2 is important because it:

• Contributes to ATP metabolism, supporting energy levels
• Helps the cells to grow and function normally
• Helps to maintain eye and skin health
• Helps to maintain healthy blood cells
• Minimizes free radical damage [4]

Dr. Axe notes that riboflavin functions synergistically with other B-complex vitamins. For example, this vitamin is important for pathways that involve vitamin B6 (pyridoxine), vitamin B9 (folate) and vitamin B3 (niacin).

When possible, Dr. Axe says this vitamin should be obtained primarily from organic food sources or taken as an ingredient in a high-quality multivitamin product that contains other B-complex family members as well in balanced dosages. [4]

The UMM states that B vitamins are critical for human health. They have integral roles in the health of the heart, skin, eyes, blood, and nerves.

B-complex vitamin supplements are used to support healthy inflammation, hormone balance, metabolism and digestive health. [1]

All B vitamins are water-soluble and not fat-soluble. That means they are not stored in fat cells and do not form solutions with lipid molecules in the body.

Unlike fat-soluble vitamins like Vitamin D, the human body cannot store these molecules for future use. Only vitamin B12 is stored in any substantial amount in the body.

All other B-complex vitamins must be consumed regularly to maintain proper levels. Dr. Axe states that the intake of fresh, vitamin B2 rich foods every day can help ensure adequate availability and facilitate its various physiological roles. [4]

Mechanisms of Action

The Natural Medicines Comprehensive Database (NMCD) describes a number of mechanisms of action for endogenous vitamin B2 in humans. [5]

Riboflavin helps to convert proteins, carbohydrates and fats from the diet into usable energy for the body. It is important for the production of ATP, which is subsequently used by every cell in the body to fuel various functions.

The process of tissue respiration (breathing) requires this vitamin. In cellular respiration, riboflavin is converted into FMN (flavin mononucleotide) and then into FAD (flavin adenine dinucleotide).

FMN and FAD act as hydrogen carriers in various flavoproteins. The primary role of hydrogen carriers is to transport hydrogen atoms needed to convert ADP (adenosine diphosphate) into ATP.

Flavoproteins are enzymes that are then used in intermediary metabolism, oxidation/reduction of organic substrates and in maintaining structural and functional integrity of red blood cells (erythrocytes).

Vitamin B2 Uses and Health Benefits

The NMCD reports that people take vitamin B2 supplement for a variety of purposes. Some of the most common uses include:

• Burning feet syndrome
• Carpal tunnel syndrome
• Cervical cancer
• Migraine headaches
• Multiple acylcoenzyme A dehydrogenase deficiency
• Red blood cell aplasia (abnormal development and/or function)
• Reproductive function [5]

Vitamin B2 is also used for muscle cramps, glaucoma, cataracts, eye fatigue, and acne. It is also sometimes used for congenital methemoglobinemia, a condition where hemoglobin cannot transport oxygen in the blood properly. [5]

NMCD states that vitamin B2 is also used for increasing energy, strengthening immunity, improving hair/skin/nail/mucous membrane health, anti-aging, and memory loss. It is also used for burns, canker sores, ulcers, alcoholism, liver disease, and lactic acidosis. [5]

NMCD has rated vitamin B2 as Effective for preventing and improving ariboflavinosis. Ariboflavinosis is the medical term for vitamin B2 deficiency.

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

Preliminary clinical research shows positive effects from using vitamin B2 for cervical cancer, esophageal cancer, and lactic acidosis. However, more research will be needed to rate the effectiveness for these uses.

More research is needed in most cases to determine the therapeutic efficacy of vitamin B2. Many of its common uses in alternative medicine require additional study to validate.

A high dose (400 mg) riboflavin product is approved by the FDA as a prescription medication and is typically used for migraine headaches. This supplement is not approved by the FDA for the prevention or treatment of any other medical conditions.

Migraine Headaches

Migraine headaches are believed to be caused by impaired mitochondrial metabolism. The mitochondria are the structures that produce energy inside all cells.

Researchers began investigating vitamin B2 as a possible migraine treatment because it is known to be involved in mitochondrial synthesis of ATP.

Physicians commonly prescribe vitamin B2 for patients who suffer migraine headaches. As a preventive treatment for patients who routinely experience severely painful migraines, 400 mg daily doses are common. [4]

In multiple clinical research studies, this vitamin has been shown to benefit migraine sufferers by reducing incident frequency, decreasing pain and other symptoms, and reducing the duration of single incidences. [5]

Some studies have demonstrated efficacy of this vitamin for reducing migraine duration and frequency compared to pre-treatment. Research trials have also shown a significant improvement in the frequency, severity, and duration of attacks compared to placebo groups. [5]

According to the NMCD, some researchers have suggested that riboflavin may be as effective for reducing migraine frequency as commonly-prescribed pharmaceutical treatments such as the beta-blockers bisoprolol (Zebeta) and metoprolol (Lopressor). [5]

According to Dr. Axe, the optimal dose of vitamin B2 for treating or preventing migraines has not yet been determined. Many studies have used 400 mg daily doses, divided up into several smaller servings and administered throughout the day.

This is significantly higher than the recommended dietary intake of this vitamin for healthy adults. Uses should not take this dosage without first consulting with a doctor to determine whether this is the right treatment for them.

Cancer Research

Preliminary studies have looked at the effects of riboflavin on cancer-affected cells in in vitro models. However, it is too early to determine whether this supplement can reduce cancer risk in humans.

The risk of developing cancer increases with exposure to free radical molecules that cause damage to our cells and introduce mutations into our DNA.

Radical agents that cause oxidative damage include free radicals like superoxide that are created inside our cells when fats are metabolized (oxidized). [2]

Some other free radicals that humans are exposed to regularly include environmental pollutants, chemicals used in farming, food and water additives, and certain pharmaceutical drugs.

Over time, with routine exposure to high levels of these free radical substances, our cells and tissues can become damaged.

Antioxidants are compounds that can reduce the production and effects of free radicals in the body. Antioxidants quench unpaired electrons on free radical molecules, helping to prevent oxidative stress.

Vitamin B2 is needed for the reduction of one of the body’s most important endogenous antioxidants: glutathione. This enzyme converts oxidized glutathione into its reduced form. [2]

Riboflavin also influences levels of three other antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidase. Getting adequate amounts of this vitamin in the diet may help to support antioxidant protection.

Some preliminary evidence suggests that vitamin B2 might have benefits for colorectal, esophageal, cervical, and prostate cancer. However, more research is required to confirm the results of these studies and determine the therapeutic efficacy of riboflavin for various cancers.

If you have concerns about cancer and are interested in taking riboflavin then you should discuss this with a doctor or oncologist.

Anemia

Anemia is a condition often marked by fatigue and weakness. It is caused by deficiency in either erythrocytes (red blood cells) or hemoglobin in the blood.

Vitamin B2 can influence anemia in several different ways. It may prevent or reverse anemia by:

• Enhancing the ability for hemoglobin to transport oxygen in the blood
• Helping to stop blood loss via hemorrhage
• Helping to mobilize iron into blood cells
• Increasing production of red blood cells

When the body lacks sufficient riboflavin, inadequate red blood cell production and oxygen underutilization become more likely.

This can cause symptoms including labored breathing, persistent fatigue, and an inability/unwillingness to engage in physical activities. [2]

Primarily by interfering with proper iron absorption, Vitamin B2 deficiency can contribute to anemia. Supplementing with riboflavin can help to restore proper iron levels in the body and improve anemia symptoms.

Cardiovascular Health

The health of blood vessels in the cardiovascular system can be affected by elevated levels of homocysteine. Vitamin B2 is associated with healthy levels of the amino acid homocysteine in the blood.

Homocysteine is produced as a by-product from the methylation of another amino acid, methionine. Homocysteine can be converted back to methionine as needed and also is used to produce the amino acid cysteine.

Having too much homocysteine in the blood does not cause any noticeable symptoms at first. However, high levels over time can cause damage to the inside of blood vessels.

This increases the risk of developing arterial plaque accumulations which may lead to atherosclerosis (clogged, hardened arteries). [2]

Atherosclerosis is the primary cause of CAD (coronary artery disease), the leading cause of heart disease. Riboflavin is purported to inhibit cholesterol accumulation by reducing free radical and homocysteine damage inside blood vessels. [2]

In research studies, the benefits of riboflavin for reducing homocysteine have only been observed in people who have the TT genotype for the methylenetetrahydrofolate reductase (MTHFR) enzyme.

Reduction effects have not been seen in people who have CC or CT genotypes.

At this time, it is not known if elevated homocysteine levels are an after-effect of cardiovascular disease, or if they are a cause. It has not been determined whether reducing homocysteine levels results in a decrease in risk of cardiovascular disease independent of other changes.

Currently, there is not enough reliable evidence available to determine the efficacy of vitamin B2 for preventing or treating atherosclerosis, CAD, heart disease or any other cardiovascular condition.

There have been some promising preliminary research studies, but more research is necessary to determine the therapeutic efficacy of riboflavin for these uses.

Eye/Vision Health and Vitamin B2

Multiple studies have associated low riboflavin levels with increased risks for some eye/vision problems. Vitamin B2 is purported to be helpful for preventing glaucoma (increased intraocular pressure), keratoconus (progressive corneal thinning) and cataracts (opaque lenses). [5]

For treating these and other eye/vision disorders, vitamin B2 is commonly applied in liquid drop form into the affected eye. This allows for direct, deep penetration into eye tissue.

The lens of the eye is particularly vulnerable to vitamin deficiencies. Population studies have found that a high dietary intake of riboflavin is associated with a decreased risk of cataracts compared to people who consume lower amounts of vitamin B2. [5]

According to the NMCD in research it has been seen that patients who take 3 mg/day riboflavin in combination with 40 mg/day niacin (vitamin B3) are less likely to develop nuclear cataracts compared to those taking a placebo agent. [5]

The NMCD has rated vitamin B2 as Possibly Effective for cataracts. Research is still ongoing in this area to determine the effects riboflavin supplementation may have cataracts in other areas of eye health.

If you are interested in taking vitamin B2 for your eye health then it is recommended to speak with your optometrist.

Additional Benefits

Vitamin B2 supplements are purported to promote greater energy levels, athletic performance, stress relief and mood balance. However, more research is needed to determine the effects of supplemental B2.

Vitamin B2 is required for the body to break down foods into usable forms of energy and to produce ATP. For this reason, it is sometimes promoted as an energy-boosting product.

However, it is not known whether increasing your intake of this vitamin can enhance energy levels in people who already consume enough to avoid deficiency.

Riboflavin also affects thyroid activity and the function of the adrenal glands. For this reason, it is sometimes promoted for weight loss, to reduce fatigue and to promote physical performance.

B2 is important for hormonal balance. Having too little of this vitamin in the diet increases the risk of developing thyroid dysfunction/disease. However, it is not known whether increasing intake will boost thyroid hormone levels or increase metabolism.

Dr. Axe says that riboflavin is “useful in calming the nervous system, battling chronic stress, and regulating hormones which control appetite, energy, mood, temperature, and more.” [4]

These claims have not been evaluated by the FDA. More research is needed to determine whether this vitamin works for these purported uses or not.

Vitamin B2 Deficiency

In the United States, vitamin B2 deficiency is rare. According to the National Health and Nutrition Examination Survey (NHANES), less than 6% of the population has a dietary intake below the Estimated Average Requirement (EAR).

According to the Linus Pauling Institute, riboflavin deficiency is rarely seen in isolation. Instead, it frequently occurs in combination with deficiencies of other water-soluble vitamins. [6]

According to the NMCD, those most at risk for developing ariboflavinosis include alcoholics, the elderly, and those who are chronically ill. People with liver disease, HIV infections, and/or malignant tumors are also at risk of deficiency. [5]

Ariboflavinosis is marked by multiple symptoms including:

• Fatigue
• Inflammation in the corners of the mouth (cheilosis, angular stomatitis)
• Inflammation of the cornea (keratitis)
• Insufficient hemoglobin levels (normocytic anemia)
• Insufficient number of red blood cells (normochromic anemia)
• Nerve damage/dysfunction (neuropathy)
• Red, itchy and/or scaly scalp (seborrheic dermatitis)
• Scrotal skin alterations
• Sluggish metabolism
• Sore throat
• Swollen, red and/or bumpy tongue (glossitis)

Some researchers believe that vitamin B2 deficiency is a contributing factor to lactic acidosis which commonly manifests in HIV patients using medications including NRTI (nucleoside analog reverse transcriptase inhibitor) drugs, AZT, Retrovir (zidovudine), Zerit, and d4T (stavudine). [5]

It has been observed that taking oral vitamin B2 supplements for up to one year prevents riboflavin deficiency and can improve symptoms of ariboflavinosis. [5]

Vitamin B2 Food Sources

According to Dr. Axe, some of the best foods to eat to increase your vitamin B2 status include brewer’s yeast, green leafy vegetables, raw milk and cheese, eggs, liver, kidney, almonds, legumes and mushrooms. [4]

Cruciferous vegetables like broccoli, cauliflower and Brussels sprouts are also good riboflavin sources. There are numerous other foods that contain this vitamin as well.

It is typically found in foods in the form of flavin mononucleotide (riboflavin-5’-phosphate) and flavin adenine dinucleotide. Only 10% of food content is in other forms, such as free riboflavin, glycosides and esters.

The following are some good food sources with their respective content in milligrams per serving:

• Beef, chicken, lamb, veal and turkey liver: 3.9 mg per 3-ounce serving
• Seaweed: 2.5 mg per 1-cup serving
• Beef and lamb kidneys: 2.5 mg per 3 ounces
• Mollusks and cuttlefish: 1.5 mg per 3 ounces
• Organic feta cheese: 1.3 mg per cup
• Almonds: 1 mg per cup
• Grass-fed beef and lamb: 0.87 mg per 3 ounces
• Mackerel: 0.49 mg per 3 ounces
• 1 large egg: 0.26 mg

Cooking foods does not seem to lessen its riboflavin content, however exposure to light destroys it.

Dr. Axe recommends storing these foods away from any light source. He also says it is better to steam or roast foods instead of boiling or scalding them.

Vitamin B2 Supplements

When possible, it is recommended to obtain the vitamin B2 you need from fresh organic fruits, vegetables, meats, and dairy sources.

However that is not possible for some people, and in these cases taking a high quality supplement may be useful.

There are a large variety of supplements available that contain riboflavin either as a single ingredient or combined with other vitamins and minerals. It is generally included as one ingredient in B-complex multivitamins. These are available in tablet and capsule forms.

The most commonly available dosages of single ingredient riboflavin supplements are 25, 50, and 100 mg. When it is included in a B-complex multivitamin the serving sizes are typically lower and average between 20-75 mg per dosage.

Do your research when shopping and compare between different riboflavin supplements. Look for trusted manufacturers who produce high quality products.

Note that it is generally not recommended to supplement the diet with individual B-complex vitamins on their own. This can lead to an imbalance with the other B vitamins.

It is recommended to balance your intake of all B-complex members because they are known to work together.

Be sure to protect vitamin B2 supplements from exposure to light to maintain their effectiveness.

Vitamin B2 Dosage Recommendations

The Food and Nutrition Board at the Institute of Medicine has established the following recommended daily allowance (RDA) levels for vitamin B2:

• 0.3 milligrams daily for infants between 0 and 6 months of age
• 0.4 mg/day for infants between 7 and 12 months
• 0.5 mg/day for children between 1 and 3 years
• 0.6 mg/day for children between 4 and 8 years
• 0.9 mg/day for children between 9 and 13 years
• 1.3 mg/day for males 14 years and older
• 1.0 mg/day for females between 14 and 18
• 1.1 mg/day for women over 18 [7]

When taken as a dietary supplement, dosages typically range from 25-100 mg per day.

In research on cancer prevention, 80 mg of riboflavin has been taken for up to 20 months. Other studies have used 5 mg daily for up to 9 years.

Various studies on migraines have administered 200-400 mg of vitamin B2 daily for up to three months. Some studies have used much lower dosages of 25 mg per day for headaches.

You should discuss the best dose for you with a doctor or other qualified health professional.

Vitamin B2 Side Effects and Interactions

Riboflavin has been given Generally Recognized as Safe (GRAS) status by the FDA. The NMCD has rated vitamin B2 supplements as Likely Safe when used orally and appropriately.

The NMCD also rates this vitamin as Likely Safe for oral use in pregnant and lactating women at RDA levels. It is rated Possibly Safe when used orally and appropriately at higher doses in the short-term.

There is no daily tolerable upper intake level (UL) for riboflavin. According to the NMCD, consumption of high dosages has limited potential for causing harm due to poor absorption of this vitamin from the gut and a high rate of excretion. [5]

Vitamin B2 is typically very well tolerated as a dietary supplement. Large doses might cause diarrhea or turn urine a yellow-orange color.

There are interactions between vitamin B2 and certain medications, nutrients, laboratory tests, and health conditions.

Some drugs that vitamin B2 might interact with include anticholinergic drugs, phenobarbital, Probenecid, and tetracyclic antibiotics.

Some drugs that can affect vitamin B2 status include antibiotics, Thorazine (chlorpromazine), Rubex (doxorubicin), and oral contraceptives.

Blond psyllium, boron, iron, and folic acid can also affect how vitamin B2 is absorbed in the body.

You should seek medical advice about using a vitamin B2 supplement to address a specific health goal. Consult with a doctor before taking this supplement if you use prescription medications and/or have any existing health conditions.

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