Riboflavin:Functions, Sources,Biosynthesis and Side Effects

Riboflavin is a type of B vitamin. It is water soluble, which means it is not stored in the body. Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. The body keeps a small reserve of these vitamins.

Functions

Riboflavin (vitamin B2) works with the other B vitamins. It is important for body growth. It helps in red blood cell production. It also aids in the release of energy from proteins.

Sources

Riboflavin is unique among the water-soluble vitamins in that milk and dairy products make the greatest contribution to its intake in Western diets. Meat and fish are also good sources of riboflavin, and certain fruit and vegetables, especially dark-green vegetables, contain reasonably high concentrations.

Biosynthesis

Biosynthesis takes place in bacteria, fungi and plants, but not animals.The biosynthetic precursors to riboflavin are ribulose 5-phosphate and guanosine triphosphate. The former is converted to L-3,4-dihydroxy-2-butanone-4-phosphate. Guanosine is degraded to 4-hydroxy-2,4,5-triaminopyrimidine, which is transformed into 5-amino-6-(D-ribitylamino)uracil. These two compounds are then the substrates for the penultimate step in the pathway, catalysed by the enzyme lumazine synthase in reaction EC 2.5.1.78.

Side Effects

In humans, there is no evidence for riboflavin toxicity produced by excessive intakes and absorption becomes less efficient as dosage increases. Any excess riboflavin is excreted via the kidneys into urine, resulting in a bright yellow color known as flavinuria.During a clinical trial on the effectiveness of riboflavin for treating the frequency and severity of migraines, subjects were given up to 400 mg of riboflavin orally per day for periods of 3–12 months. Abdominal pains and diarrhea were among the side effects reported.