Riboflavin: intake, status, and relation to anemia among women of reproductive age

Abstract

Riboflavin is a B-vitamin that is essential for redox reactions. Erythrocyte glutathione reductase activity coefficient (EGRac) is a biomarker of riboflavin status; ratios 1.40 are commonly interpreted as indicating biochemical deficiency. Biochemical riboflavin deficiency may contribute to anemia; however, little is known about the riboflavin status and relationship to anemia in reproductive-aged women. The objective of my thesis was to determine riboflavin status and relationship with anemia in women of reproductive age in Canada, Malaysia, and Cambodia. The first study determined riboflavin status and its association with hemoglobin and anemia in women (19-45y) living in Canada (n=206) and Malaysia (n=210). Riboflavin deficiency (EGRac 1.40) was more prevalent in Malaysian than Canadian women (71% vs. 40%). A negative association between EGRac and hemoglobin (r= -0.18; P<0.001) was observed (pooled sample; n=416). After adjusting for confounders, this association remained significant, but EGRac explained only 1% of the variance in hemoglobin. Women with riboflavin deficiency were twice as likely to have anemia (hemoglobin <120 g/L) compared to women with EGRac <1.40. Inadequate dietary riboflavin intakes (<0.9 mg/d) were observed in 7% of Canadian women; no association between dietary riboflavin intake and EGRac was observed (B= -0.03, 95%CI: -0.07, 0.01). The second study was a secondary analysis of an intervention trial to determine the effect of a daily multiple micronutrient supplement (MMN) (1.4 mg of riboflavin), iron (60 mg), iron+MMN, or placebo for 12 weeks on riboflavin status and on hemoglobin concentrations in Cambodian women (18-45y; n=226) with anemia. At 12 weeks, the women who received MMN (n=112), with or without iron, had lower EGRac than the women who did not (mean difference= -0.39, 95%CI: -0.48, -0.31). The improvement in riboflavin status was not predictive of the change in hemoglobin concentration at 12 weeks. Biochemical riboflavin deficiency was common in the Canadian and Malaysian women, but the contribution of riboflavin status to hemoglobin was small. The high prevalence of apparent biochemical deficiency in Canadian women, despite adequate dietary intakes, suggest that the EGRac cut-offs may need re-evaluation. Supplementation with MMN for 12 weeks lowered EGRac in Cambodian women, but did not increase hemoglobin concentration.