Riboflavin (vitamin B2) functions and deficiency
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Riboflavin (Vitamin B2) Functions in Human Health
Energy Metabolism and Cellular Processes
Riboflavin (vitamin B2) is a water-soluble vitamin that is essential for human health because the body cannot produce it and must obtain it from the diet Balasubramaniam2019Mosegaard2020Aragão2024. Inside cells, riboflavin is converted into two active coenzymes: flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) Balasubramaniam2019Henriques2010Mosegaard2020+3 MORE. These coenzymes are crucial for many enzymes (flavoproteins) that drive key metabolic processes, including:
- Mitochondrial energy production (especially in the electron transport chain)
- Fatty acid β-oxidation
- Amino acid and carbohydrate metabolism
- Redox reactions and antioxidant defense
- DNA repair, protein folding, and apoptosis
- Synthesis of other vitamins (e.g., activation of vitamin B6 and synthesis of niacin) Balasubramaniam2019Henriques2010Mosegaard2020+4 MORE
Riboflavin also plays a role in the metabolism of folate and interacts with vitamins B6 and B12, supporting one-carbon metabolism and homocysteine regulation Ranjit2024Tan2020.
Immune Function and Other Physiological Roles
Riboflavin is important for immune defense, particularly in supporting the function of NADPH oxidase 2 (Nox2) in phagocytes, which is necessary for the oxidative burst that kills pathogens Schramm2014Aragão2024. It also contributes to the health of the nervous system, skin, cardiovascular system, and red blood cell production Balasubramaniam2019Aragão2024Ranjit2024.
Riboflavin Deficiency: Causes and Consequences
Causes of Deficiency
Riboflavin deficiency can result from inadequate dietary intake, malabsorption, genetic defects in riboflavin transporters, or increased physiological needs (such as during pregnancy, illness, or aging) Balasubramaniam2019Mosegaard2020Aragão2024+1 MORE. People following vegan or vegetarian diets are at higher risk because plant-based foods generally contain less riboflavin than animal-derived foods . Hypothyroidism can also impair the conversion of riboflavin to its active forms .
Clinical Manifestations
Deficiency in riboflavin can lead to a wide range of symptoms and health problems, including:
- Neuromuscular disorders and sensorimotor neuropathy
- Anemia
- Impaired immune response and increased susceptibility to infections
- Skin and mucosal lesions
- Abnormal fetal development
- Cardiovascular disease due to elevated homocysteine
- Disruption of metabolism of other B vitamins Balasubramaniam2019Mosegaard2020Schramm2014+3 MORE
In severe cases, especially with genetic transporter deficiencies, symptoms can include muscle weakness, cranial nerve deficits (such as hearing loss), sensory ataxia, feeding and respiratory difficulties, and can be life-threatening if untreated .
Subclinical and Population-Level Deficiency
Subclinical riboflavin deficiency is more common than previously thought, even in developed countries, and may become clinically significant when combined with genetic or environmental stressors Mosegaard2020Ranjit2024Tan2020. There is no universally adopted method for assessing riboflavin status, but plasma riboflavin concentration and the erythrocyte glutathione reductase activation coefficient (EGRac) are used in research Ranjit2024Branscum2024Tan2020.
Treatment and Prevention
Riboflavin supplementation is safe, as excess is rapidly excreted in urine, and can be lifesaving in cases of genetic transporter deficiencies or inborn errors of metabolism Balasubramaniam2019Mosegaard2020Aragão2024+1 MORE. Early recognition and prompt treatment are crucial, especially in genetic disorders affecting riboflavin transport or metabolism Balasubramaniam2019Jaeger2016.
Conclusion
Riboflavin is vital for energy metabolism, redox balance, immune function, and the metabolism of other vitamins. Deficiency can have widespread and serious health effects, but is preventable and treatable with adequate dietary intake and supplementation when needed. Awareness of risk factors and early intervention are key to maintaining optimal health.
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