Vitamin B2

Figure 1. The chemical structure of Vitamin B2 (or Riboflavin).

Vitamin B2 or Riboflavin is a micronutrient and one of eight essential B vitamins. Vitamin B2 is a water soluble vitamin. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide, that are involved in energy metabolism, cellular respiration, and antibody production, as well as normal growth and development. The coenzymes are also required for the metabolism of Niacin (or Vitamin B6) and folate. Vitamin B2 helps break down proteins, fats, and carbohydrates, converting them into adenosine triphosphate (i.e. energy for cells).

In the human body, bacteria in the gut can produce small amounts of Vitamin B2, but not enough to meet dietary needs. Most Vitamin B2 is used immediately and not stored in the body, so excess amounts are excreted in the urine. Excessive intake of Vitamin B2 such as from supplements can cause urine to turn bright yellow. Vitamin B2 can be degraded by heat, so cooking foods naturally reduces the bioavailability of Vitamin B2.

Food Sources

Vitamin B2 can be found in meat, fortified foods, some nuts and green vegetables. Examples include:

• Dairy milk
• Yogurt
• Cheese
• Eggs
• Lean beef and pork
• Beef liver
• Chicken breast
• Salmon
• Fortified cereal and bread
• Almonds
• Spinach

Taken as a Dietary Supplement

As a dietary supplement, Vitamin B2 is mainly used to treat Vitamin B2 deficiency. While rare, Vitamin B2 deficiency can be caused by disorders of the thyroid and by other nutrient deficiencies, such as in those who are malnourished. Symptoms of Vitamin B2 deficiency include:

• Cracked lips
• Sore throat
• Swelling of the mouth and throat
• Swollen tongue (glossitis)
• Hair loss
• Skin rash
• Anaemia
• Itchy red eyes
• Cataracts in severe cases

Vitamin B2 is also commonly promoted as a supplement to help with migraines and to reduce the risk of cardiovascular diseases.

The Recommended Dietary Allowance for Vitamin B2 for men and women ages 19+ years is 1.3mg and 1.1mg daily, respectively. For pregnancy and lactation, the amount increases to 1.4mg and 1.6mg daily, respectively. Being a water soluble vitamin, Vitamin B2 is well tolerated in the human body thus unlikely to cause adverse side effects from high Vitamin B2 intake.

Background

Vitamin B2 (Riboflavin) is listed in the World Health Organization's List of Essential Medicines.