Riboflavin (formerly vitamin G) is part of the vitamin B complex, and known as vitamin B2. It is a yellow-orange solid which gives many supplements their colour, the name being derived from the Latin word for yellow. Riboflavin is required for a number of enzyme reactions in the body, including the activation of other nutritional elements such as fatty acids, iron and proteins.
Riboflavin has an antioxidant role, scavenging cell-damaging free radicals and reducing the risks of heart disease; it helps the body to metabolise folate and vitamin B6 and is important in activating iron for red blood cell production and growth.
Good sources of riboflavin are liver and kidney, cheese, eggs, milk, legumes and leafy vegetables. It is often added to vitamin-enriched breakfast cereals and grain products such as flour and pasta, as much of the vitamin content is lost in refining processes. It can also be added to baby food and meal replacements, and in Europe comprises the yellow food colouring E101.
Deficiency effects are similar to those of niacin deficiency, including skin lesions, inflammations of the mouth and genitalia, and significant birth defects if deficient during pregnancy. Gluten-free diets also run a risk of being riboflavin-deficient.