Vitamin B2 (riboflavin)

Vitamin B2, also called riboflavin, is a water-soluble, yellow-coloured and light-sensitive vitamin. It occurs mainly in dairy products, eggs, meat, fish, wholegrains and some vegetables. In the body it is converted into its active forms, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). The stores are small, and excess amounts are excreted. Vitamin B2 is measured in blood. In the evidence profiles for migraine it is looked at because an altered energy metabolism of the nerve cells is discussed there and riboflavin is indispensable for the mitochondria.

What vitamin B2 does in the body

FMN and FAD are coenzymes of numerous enzymes that transfer electrons. In the respiratory chain of the mitochondria they work in complexes I and II, thereby enabling the formation of ATP. In the breakdown of fatty acids (β-oxidation), the acyl-CoA dehydrogenases depend on FAD. Glutathione reductase needs FAD to return used glutathione to its antioxidant form. Other vitamins also depend on riboflavin: vitamin B6 is activated with the help of FMN, niacin is formed from tryptophan via an FAD-dependent enzyme, and MTHFR in folate metabolism needs FAD to break down homocysteine.

Low vitamin B2 – what happens in the body?

With a deficiency, the flavin-dependent enzymes work more slowly. The mitochondria gain less energy from fat and sugar, antioxidant defence via glutathione weakens, and vitamin B6 and niacin are activated less well – a B2 deficiency therefore often brings further shortages with it. Homocysteine can rise, especially in people with the genetic MTHFR variant 677TT. Typical signs appear on skin and mucous membranes: cracked corners of the mouth, a red, smooth tongue, inflamed lips, scaly patches of skin on the nose and forehead, and light-sensitive, burning eyes. The use of iron for blood formation can also suffer. Common reasons are a diet with few dairy products and little meat, alcohol and absorption disorders in the gut.

High vitamin B2 – what happens in the body?

Riboflavin is water-soluble and absorbed in the gut only in limited amounts; whatever the body does not need is excreted via the kidneys. This colours the urine bright yellow but is harmless. No harmful effects from vitamin B2 in food or usual preparations are known. High blood levels usually result from a generous intake via vitamin preparations in the period before the blood sample and then mainly show well-filled stores. Because riboflavin is light-sensitive, the sample is transported protected from light – so the measured value remains meaningful.

The interpretation is given in your report.