Vitamin B2

Riboflavin (also known as vitamin B2) is one of the B vitamins, which are all water soluble. Riboflavin is naturally present in some foods, added to some food products, and available as a dietary supplement. This vitamin is an essential component of two major coenzymes, flavin mononucleotide (FMN; also known as riboflavin-5’-phosphate) and flavin adenine dinucleotide (FAD). These coenzymes play major roles in energy production; cellular function, growth, and development; and metabolism of fats, drugs, and steroids [1-3]. The conversion of the amino acid tryptophan to niacin (sometimes referred to as vitamin B3) requires FAD [3]. Similarly, the conversion of vitamin B6 to the coenzyme pyridoxal 5’-phosphate needs FMN. In addition, riboflavin helps maintain normal levels of homocysteine, an amino acid in the blood [1]. More than 90% of dietary riboflavin is in the form of FAD or FMN; the remaining 10% is comprised of the free form and glycosides or esters [2,3]. Most riboflavin is absorbed in the proximal small intestine [4]. The body absorbs little riboflavin from single doses beyond 27 mg and stores only small amounts of riboflavin in the liver, heart, and kidneys. When excess amounts are consumed, they are either not absorbed or the small amount that is absorbed is excreted in urine [3]. Bacteria in the large intestine produce free riboflavin that can be absorbed by the large intestine in amounts that depend on the diet. More riboflavin is produced after ingestion of vegetable-based than meat-based foods [2]. Riboflavin-5-Phosphate is a metabolically active form of Riboflavin that is formed naturally in the mitochondria. The exact dose equivalency between riboflavin and riboflavin-5-phosphate has not been fully delineated. Riboflavin is important for a number of different cellular functions including: In coenzyme form [FAD] as part of the Citric Acid cycle involved in energy metabolism and the metabolism of certain neurotransmitters [5, 6] For the health of red blood cells and mucous membranes [7] In glutathione metabolism and in relation to the integrity of skin and mucous membranes [8] For normal vision helping to protect from oxidative damage [9]