Vitamin B₂-Also known as riboflavin, this water- soluble vitamin is also known as a flavin. A flavin is any compound that happens to contain in its structure, what is known as an isoalloxazine molecule. It is not essential to know this, but rather more importantly in regards to function what the vitamin does for us. This flavin functions as a component of FAD (flavin adenine dinucleotide) and FMN (flavin mononucleotide). FMN abd FAD are known as flavoproteins. Tlavoproteins are simply proteins that contain the flavin molecule as described above. These flavoproteins act as enzymes to speed up reactions in our body. Otherwise, chemical reactions in our body would take infinitely longer and this would affect our health. For these enzymes to work efficiently, some of them need riboflavin. This flavin helps the enzyme to work properly. With riboflavin dificiencies, the enzyme cannot work properly, if at all. This can obviously have an impact on our health, since riboflavin dependent enzymes perform functions such as the metabolism (oxidation) of carbohydrates that we use for energy. FAD and FMN function as electron carriers in oxidation-reduction reactions. Riboflavin kinase is an enzyme that catalyzes the addition of phosphate to riboflavin to form FMN, a cofactor for electron transfer reactions.

Basically, riboflavin is converted to its active forms, which are FMN and FAD, as discussed above. Once the active forms of riboflavin (FAD, FMN) are produced, they can reversibly bind with hydrogen (H), thus forming FADH₂ and FMNH₂. FADH₂ and FMNH₂ functions in metabolic pathways, essential to survival. Coenzyme Q can accept hydrogens from FADH₂ and FMNH₂ during the reactions from fatty acid degradation and other pathways.

Sources of riboflavin

Good sources of riboflavin are eggs, milk, liver, and green leafy vegetables. Vegetarians who subtract milk from their diets obtain only a marginal supply of riboflavin. Ultraviolet wavelengths in sunlight can break bonds in the riboflavin molecule, thereby rendering it useless.

RDA of riboflavin

Like thiamine the amount of riboflavin required depends on the caloric intake of the individual. 0.6 mg (milligrams) are required for every 1000 kcal of dietary intake. For the average male, with an intake of 3000 kcal, this is equivalent to 1.8 mg of riboflavin per day. A minimum of 1.2 mg/day of riboflavin is recommendd for adults.

Riboflavin deficiency

Deficiency of riboflavin is referred to as ariboflavinosis, and is characerized by dermatitis, cheilosis (cracks or fissuring at the corners of the mouth), and glossitis (a smooth and purple tongue). Riboflavin deficincies normally are not observed on their own, but usually in conjunction with other vitamin deficiencies (eg., economically impoverished areas, starvation). However, araboflavinosis can be observed in select cases, such as in practicing incorrect vegetarianism, those suffering from alcoholism, chronic infections, advanced cancer and other debilitating diseases.

Riboflavin as an additive in foods

Riboflavin is added to foods for reasons of fortification and colouring. For example, fortifying cereals, drinks, slimming and diet supplements, as well as other foods with riboflavin helps in ensuring proper amounts of riboflavin in our diet. Riboflavin is also used in a small percentage of foods as a colouring. This is acceptable, considering that it is a vitamin. Is riboflavin always riboflavin ?!! Where does riboflavin present a problem?