Riboflavin – Vitamin B2 / G

Vitamin B2, also referred to as riboflavin or Vitamin G, is one of eight B vitamins that are water-soluble.

It aids in the body’s conversion of foods or carbohydrates into glucose, which is primarily the body’s fuel, in order to produce energy.

The body does not store B vitamins as they are water-soluble. This group is also referred to as the B complex vitamins; they aid in the body’s metabolizing of proteins and fats; and are vital for healthy skin, eyes, hair, and liver.

The Biological Role of Riboflavin

The glutathione reductase, a FAD-dependent enzyme, participates in the glutathione’s redox cycle. The redox cycle of glutathione plays a significant role in the protection of organisms against hydroperoxides and other reactive oxygen species. The energy of living organisms is derived mostly from oxidation-reduction (redox) reactions, which are processes wherein electron transfer is involved. Flavocoenzymes are crucial for the metabolism of proteins, fats, and carbohydrates, and participate in redox reactions in several metabolic pathways.

Aside from the energy production for the body Riboflavin also serves as an antioxidant by fighting free radicals (damaging unpaired electron particles in the body). Free radicals can damage the cell membrane, DNA, and cells in general, and are also one of the factors of the aging process. The development of cancer, heart disease, and other health conditions are also associated with free radicals.

Riboflavin and other antioxidants fight free radicals and help to limit or even prevent some of the damages that free radicals cause.

Riboflavin is required by the body in order to convert folate and vitamin B6 into forms that are biologically active.

Vitamin B2 is also essential for the production of red blood cells as well as for the body growth as a whole.

Riboflavin Deficiency

The majority of healthy people who have a well-balanced diet will naturally consume adequate quantities of vitamin B2. However, alcoholics and elderly people can be at risk of having a riboflavin deficiency due to poor unhealthy diet.

Some of the symptoms of having riboflavin deficiency are digestive problems; slowed growth; sores and cracks around the corners of the mouth; fatigue; moist, scaly skin inflammation or seborrheic dermatitis; eye fatigue; sensitivity to light; swelling and soreness of the throat; and swollen magenta-colored tongue or redness and inflammation of tongue.

The medical term for deficiency of riboflavin is ariboflavinosis; this condition is often seen in combination with deficiencies of other water-soluble vitamins and rarely found in isolation.

Other symptoms of having a riboflavin deficiency can involve blood vessel formation in the eye’s clear covering or the vascularization of the cornea; and normochromic normocytic anemia, which is decreased red blood cell count where the existing red blood cells contain normal levels and normal size of hemoglobin.

Severe deficiency of riboflavin can result to decreased conversion of vitamin B6 to PLP or its coenzyme form; and decreased conversion of tryptophan to niacin.

Preeclampsia is another deficiency symptom of having ariboflavinosis, which is the presence edema (swelling), protein in urine, and elevated blood pressure during pregnancy. 5% of the total women with preeclampsia may be susceptible to the development of eclampsia, a major cause of maternal death.

Riboflavin Recommended Dietary Allowance (RDA)


FEMALES (mg/day)

MALES (mg/day)

0 to 6 months 0.3 AI 0.3 AI
7 to 12 months 0.4 AI 0.4 AI
1 to 3 years 0.5 0.5
4 to 8 years 0.6 0.6
9 to 13 years 0.9 0.9
14 to 18 years 1.0 1.3
19 years and older 1.1 1.3
Pregnancy all ages 1.4
Lactating all ages 1.6

Riboflavin Food Sources

Most foods that were derived from plants and animals contain at least trace amounts of vitamin B2. Bread and wheat flour have been enriched with riboflavin, as well as iron, niacin, and thiamine, in the United States since 1943.

Some good natural Riboflavin rich foods include non-fat milk, cheddar cheese, broccoli, asparagus, spinach, beef, almonds, eggs, halibut, salmon, and whole wheat bread.


LPI; UMM; UMass; UFL; Swarthmore.