Riboflavin intake and status and relationship to anemia

Riboflavin in its coenzyme forms, flavin mononucleotide and flavin adenine dinucleotide, is essential for multiple redox reactions necessary for energy production, antioxidant protection, and metabolism of other B vitamins, such as niacin, pyridoxine, and folate. Erythrocyte glutathione reductase activity coefficient (EGRac) is a biomarker of riboflavin status; ratios ≥1.40 are commonly interpreted as indicating biochemical deficiency. Most research on riboflavin status comes from low-income countries and rural settings, which reported high rates of riboflavin deficiency and inadequate intake. However, some studies suggest that riboflavin deficiency, based on the functional indicator EGRac, is also of concern in middle- and high-income countries. Biochemical riboflavin deficiency that does not cause clinical symptoms may contribute to anemia, particularly among women and children. Riboflavin enhances iron absorption, and riboflavin deficiency decreases iron mobilization from stores. The current knowledge on riboflavin's role in metabolic processes and its biochemical status is summarized in this review, and the available evidence on the role of riboflavin in anemia among different populations is discussed.