Vitamin B2Edit

Vitamin B2, also known as riboflavin, is a water-soluble micronutrient that plays a central role in cellular energy production and a broad set of redox reactions. It exists in the body primarily as two coenzyme forms, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which act as essential prosthetic groups for a wide array of flavoenzymes. Because humans cannot synthesize riboflavin, it must be obtained from the diet or from supplements. riboflavin FMN FAD

Riboflavin and its coenzymes are involved in numerous pathways, most notably in energy metabolism. They participate in the oxidation-reduction reactions required to convert carbohydrates, fats, and proteins into usable energy. In addition to energy production, FMN and FAD are required for the activity of enzymes that support the metabolism of other vitamins and nutrients, including the conversion of tryptophan to niacin. This makes riboflavin a foundational nutrient for maintaining metabolic efficiency and overall health. energy metabolism niacin tryptophan

Biochemical and physiological overview

  • Coenzyme forms: The primary active forms are FMN and FAD. In the body, riboflavin is converted to these forms as needed by specific enzymes. FMN FAD
  • Critical reactions: FAD and FMN serve as electron carriers in multiple flavoenzymes involved in the mitochondrion’s energy-producing processes, fatty acid oxidation, and amino acid metabolism. This places riboflavin at the heart of the cell’s energy economy. redox flavoenzymes
  • Distribution and storage: Riboflavin is widely distributed in animal and plant foods, absorbed in the small intestine, and not stored in large amounts, making regular intake important. Excess is excreted in the urine, which is why riboflavin intake tends to show up as bright yellow urine when consumed in high amounts. absorption excretion

Dietary sources and intake recommendations

Riboflavin is found in a variety of foods, with particularly rich sources including dairy products, eggs, lean meats, and fortified cereals. Other sources include leafy green vegetables and some whole grains. Typical dietary patterns in many populations provide sufficient amounts, but at-risk groups may require attention to ensure adequacy. dairy products eggs liver green leafy vegetables fortified cereals

  • Adequate intake levels: In adults, dietary reference intakes are established to meet the needs of most healthy people. For adults, typical recommendations are around 1.3 mg/day for men and 1.1 mg/day for women, with higher amounts advised during pregnancy and lactation. These values are issued by public health authorities and are designed to reflect average energy expenditure and metabolic demand. recommended dietary allowance dietary reference intake
  • Special considerations: Because riboflavin is water-soluble and not stored in large reservoirs in the body, regular consumption is important. Alcohol use and certain medications can affect riboflavin status, and diets that severely restrict animal products or fortified foods can increase the risk of deficiency. ariboflavinosis

Deficiency and health implications

Deficiency of riboflavin is relatively uncommon in developed countries but can occur in contexts of malnutrition, chronic disease, or alcoholism. The clinical hallmark of riboflavin deficiency, historically described as ariboflavinosis, includes symptoms such as sore throat, mouth and lip lesions (stomatitis and cheilosis), glossitis, and anemia. In advanced cases, there may be sensitive changes in the cornea and other tissues due to impaired redox balance. Prevention and treatment rely on dietary intake or supplementation to restore adequate FMN and FAD-dependent enzyme activity. ariboflavinosis glossitis stomatitis cheilosis

Interactions, safety, and policy considerations

  • Safety profile: Riboflavin has a wide safety margin and high-dose supplementation does not typically cause serious adverse effects. No tolerable upper intake level (UL) has been established for riboflavin in many health agencies because the risk of toxicity is very low; however, very high doses may color urine and raise other benign effects. toxicity tolerable upper intake level
  • Policy and fortification debates: A recurring policy discussion centers on whether riboflavin and other micronutrients should be added to staple foods through fortification. Proponents emphasize the public health benefits of reducing deficiency and supporting health in populations with limited access to varied diets. Critics argue for greater emphasis on personal choice, market-driven product standards, and targeted supplementation for those who need it most. The right-of-center perspective on these debates often stresses limited government intervention, consumer responsibility, and the importance of transparent labeling, while recognizing that fortification can be a cost-effective public health tool in settings with high deficiency risk. In practice, riboflavin is commonly present in fortified foods and vitamin supplements, though fortification policies vary by country and region. food fortification micronutrient nutrition policy

See also