Vitamin B2

Physiological functions of vitamin B2

• Helps protect cells from oxygen damage
• Supports the production of cellular energy
• Maintain the supply of other B vitamins

Physiological events that may signal a need for greater vitamin B2 intake

• Soreness around the lips, mouth, and tongue
• Cracking of the skin at the corners of the mouth
• Tearing, burning and itching in and around the eyes
• Light sensitivity
• Peeling of the skin, particularly around the nose

Function of vitamin B2

Production of energy

Similar to vitamin B1, vitamin B2 plays a central role in energy production. In its energy production capacity, vitamin B2 typically takes the form of flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN), molecules that attach to protein enzymes and allow oxygen-based (aerobic) energy production to occur.

When FAD or FMN is complexed with these protein enzymes, they are referred to as flavoproteins. Flavoproteins are found throughout the body, particularly in heart and skeletal muscle and other locations where aerobic energy production in constantly needed.

Recycling of glutathione

Glutathione, a small, protein-like molecule known for its potent antioxidant capabilities, helps to prevent free radicals and other oxygen reactive species from causing damage to cells and tissues. Like other antioxidant molecules, glutathione must be constantly recycled back into its active form so that its activity potential can be replenished. Vitamin B2 is a cofactor for the enzyme glutathione reductase, a catalyst for converting the oxidized form of glutathione back to it reduced, active form.

Maintainance of vitamin B3 supplies

Vitamin B2 plays an important physiological role by participating in the maintenance of vitamin B3 status. Vitamin B2 (in its FAD form) is required for the functioning of kynurenine mono-oxygenase, an enzyme that participates in the conversion of the amino acid tryptophan to vitamin B3.

Causes and symptoms of vitamin B2 deficiency

Excessive alcohol consumption decreases the availability of vitamin B2. Five to ten times the ordinary amount of vitamin B2 may be required in persons with chronic alcohol abuse.

The need for vitamin B2 is increased during heavy exercise. Women training for athletic events have been shown to particularly in need of extra vitamin B2, needing up to 10-15 times the ordinary amount.

Early stage riboflavin deficiency symptoms oftentimes manifest as eye problems including sensitivity to light, tearing, loss of clear vision and burning and itching in and around the eye. Orolabial symptoms may also manifest including soreness around the lips, mouth and tongue and cracking of the skin at the mouths corners. In addition, inadequate vitamin B2 status can also result in peeling of the skin, especially around the nose and the scrotum.

Causes and symptoms of vitamin B2 toxicity

There have been no toxicity symptoms from food source of supplemental vitamin B2 documented in the research literature. In 1998, the Institute of Medicine at the National Academy of Sciences reviewed research on vitamin B2 and did not establish a Tolerable Upper Intake Level (UL).

Effects of cooking, storage and processing on vitamin B2

While vitamin B2 is relatively resistant to damage by heat or air, light can cause the loss of this nutrient. For example, in studies that involved the boiling of wheat noodles, temperature and water did not affect vitamin B2 loss but prolonged exposure to light did. Loss of riboflavin from cooking and storage is typically less than 25% when foods have not had prolonged exposure to light. Therefore, cook riboflavin-rich foods in covered pots and store them in opaque containers whenever possible.

Interactions between medications and vitamin B2

Medicines that decrease the availability of vitamin B2 in the body:

• Birth control pills (oral contraceptives)
• Tetracycline (antibiotic)
• Tricyclic antidepressants such as amitryptyline (Elavil) and doxepin (Sinequan)
• Primaquine (antimalarial drug)
• Probenecid (anti-gout drug)

Alcohol has also been shown to decrease the availability of vitamin B2 in the body.

Interactions that occur between vitamin B2 and other nutrients

Vitamin B2 status is strongly affected by intake of vitamin B1. While adequate supplies of B1 help to increase levels of B2, very high levels of B1 intake can increase the loss of urinary B2. Vitamin B2 is necessary in order for nutrients such as iron, folate, vitamin B3 and vitamin B12 to be fully bioavailable.

Health conditions that require special emphasis on vitamin B2

Individuals who have the following health conditions should pay special attention to their vitamin B2 status:

• Anemia
• Carpal tunnel syndrome
• Cataracts
• Migraine
• Rosacea
• Vaginitis

Forms in which vitamin B2 is found in dietary supplements.

In most dietary supplements, vitamin B2 is found in its simplest form, as riboflavin. Yet, this vitamin usually takes the form of flavinadenine dinucleotide (FAD) or flavin mononucleotide (FMN), water-soluble molecules, when active in the bodys metabolic pathways. While not widely available as a dietary supplement, riboflavin tetrabutyrate, a fat-soluble version of vitamin B2, has been the focus of research in the treatment of riboflavin-related disorders.

Foods that are concentrated sources of vitamin B2

Excellent sources of vitamin B2 include asparagus, calfs liver, crimini mushrooms, mustard greens, sea vegetables, spinach, swiss chard and yeast. Very good sources include broccoli, cabbage, cauliflower, chickens eggs, cows milk, kale, salmon, strawberries, tomatoes and venison.