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19: Riboflavin (Chapter 20b)

Last updated

Mar 11, 2025
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- 18.3: Conclusions (20a.3)
- 19.1: Riboflavin (20b.1)

Rosalind S. Gibson
University of Otago

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Abstract

Riboflavin is a component of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) which act as coenzymes of different flavoproteins involved in oxidation-reduction reactions that are central to energy production, intermediary metabolism, drug metabolism and the maintenance of antioxidant status. Riboflavin coenzymes are also required for the metabolism of folate, vitamin B₁₂, vitamin B₆, and niacin as well as for mobilization of iron from intracellular stores. Classical signs of riboflavin deficiency (ariboflavinosis) generally occur in association with other nutrient deficiencies, notably vitamin B₆. Riboflavin deficiency has been described predominantly in undernourished populations in low income countries, but accumulating evidence has shown that a suboptimal riboflavin status is more common than previously recognized among populations in developed countries. Measurement of the activity of glutathione reductase, with and without the prosthetic group FAD, is the best method for assessing tissue riboflavin status, particularly in cases of impaired riboflavin status. The test measures tissue saturation and long-term riboflavin status, although some confounding factors may influence its performance. Urinary riboflavin excretion levels in casual or 24h urine specimens reflect dietary intake but vary widely because concentrations are affected by many non-nutritional factors. Concentrations of riboflavin, FMN and FAD in plasma or erythrocytesG as well as measurement of the activity of pyridoxamine phosphate oxidase and its activity coefficient appear promising options for assessment of riboflavin status and warrant further exploration.

19.1: Riboflavin (20b.1)
This page discusses riboflavin, essential for energy metabolism and as a precursor for important coenzymes. Deficiency, known as ariboflavinosis, can cause various symptoms and is more likely in at-risk populations such as undernourished women and children. Certain medications and genetic factors can affect riboflavin bioavailability, leading to health risks like hypertension. Dietary sources include dairy and meat, with plant-based diets being more deficient.
19.2: Biomarkers of riboflavin status (20b.2)
This page discusses the challenges in diagnosing riboflavin deficiency, emphasizing the use of the erythrocyte glutathione reductase activity coefficient (EGR AC) for long-term status assessment. However, sensitivity issues and variations in laboratory methods complicate prevalence comparisons. Riboflavin status is further explored through urinary excretion metrics, with different assays showing discrepancies.

Abstract

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