Riboflavin - Vitamin B2

Thiamin, riboflavin, niacin, vitamin B6, pantothenic acid, biotin, folic acid, vitamin B12 and vitamin C are referred to as the water-soluble vitamins. Solubility in water is one of the only characteristics that they share. Because they are water soluble, these vitamins tend to be absorbed by simple diffusion when ingested in large amounts and by carrier – mediated processes when ingested in smaller amounts. They are distributed in the aqueous phases of the cell. Most are not stored in appreciable amounts, making their regular consumption a necessity.

Riboflavin is essential for the metabolism of carbohydrates, amino acids and lipids, supports antioxidant protection. It carries out these functions as the coenzymes flavin adenine dinocleotide and flavin adenine mononucleotide. Because of its fundamental roles in metabolism, riboflavin deficiencies are first evident in tissues that have rapid cellular turnover such as the skin and epithelia.

Riboflavin also works as an antioxidant by fighting damaging particles in the body known as free radicals. Free radicals can damage cells and DNA, and may contribute to the aging process, as well as the development of a number of health conditions, such as heart disease and cancer. Antioxidants such as riboflavin can fight free radicals and may reduce or help prevent some of the damage they cause.

Riboflavin is also needed to help the body change vitamin B6 and folate into forms it can use. It is also important for body growth and red blood cell production.

Most healthy people who eat a well-balanced diet get enough riboflavin. However, elderly people and alcoholics may be at risk for riboflavin deficiency because of poor diet. 

Dietary reference intakes of Riboflavin

Infants 0.3 – 0.4 mg/day

Children 0.5 – 0.9 mg/day

Adolescents 1 - 1.3 mg/day

Adults 1.1 - 1.3 mg/day

Pregnant 1.4 mg/day

Breastfeeding 1.6 mg/day

Riboflavin content of selected foods

Liver, beef, 3 oz (2.91 mg)

Fortified ready to eat cereals, 1 cup (1.7 mg)

Milk, 2% fat, 1 cup (0.45 mg)

Yogurt, low fat, 1 cup (0.4 mg)

Cheese, cottage, 1 cup (0.37 mg)

Egg, 1 (0.25 mg)

Custard, baked, ½ cup (0.25 mg)

Bagel, plain, 1 (0.22 mg)

Hamburger, lean, broiled medium, 3.5 oz (0.21 mg)

Chicken, dark meat, 3 oz (0.21 mg)

Cheese, American, 1 oz (0.1 mg) 

Symptoms of Riboflavin deficiency


Burning and itching of the eyes

Loss of visual acuity

A greasy eruption of the skin in the nasolabial folds, scrotum or vulva

Soreness and burning of lips, mouth, tongue


Angular stomatitis


Purplish or magenta tongue



Ulcerations of cornea



Signs of Riboflavin toxicity

Riboflavin is not known to be toxic. High oral doses are considered essentially nontoxic.

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