Liadhan McAnena, Mary Ward, Adrian McCann, Kristina Pentieva, Leane Hoey, Ryan Barlow, Harry R Jarrett, Maeve A. Kerr, JJ Strain, Catherine Hughes, Albert Flynn, Janette Walton, Yvonne Lamers, Parveen Bhatti, Crystal D Karakochuk, Kyly C. Whitfield, Michelle Murphy, Pere Cavallé, Lorna Cox, Ann Prentice, Damon A Parkington, Tabasum Makhdoomi, Sengchanh Kounnavong, Guy‐Marino Hinnouho, Nelly Birungi, Tim Green, H. McNulty
BACKGROUND: Riboflavin, as flavin mononucleotide and flavin adenine dinucleotide, is essential for numerous metabolic pathways. However, the prevalence of riboflavin deficiency worldwide remains unclear, because status biomarkers are very rarely measured in human studies. OBJECTIVES: This study aimed to investigate riboflavin status in females of reproductive age and children from several regions of the world, representing both high-income countries and low/middle-income countries (HICs and LMICs). METHODS: We measured riboflavin status in population-representative samples from Ireland, United Kingdom, Cambodia, and Democratic Republic of the Congo, and in cohort samples from HICs (Northern Ireland, Spain, Canada) and LMICs (Malaysia, Lao People's Democratic Republic, Cambodia, Uganda) using the functional assay, erythrocyte glutathione reductase activation coefficient (EGRac), with higher values indicating lower status and EGRac ≥ 1.40 indicative of deficiency. RESULTS: In Irish (n = 251) and British (n = 163) populations, among unsupplemented females of 18-45 y, median (95% confidence interval) EGRac values were 1.39 (1.36, 1.42) and 1.40 (1.36, 1.49), and 48% and 50%, respectively, had riboflavin deficiency. In Irish females, biomarker status declined progressively(P < 0.002) with decreasing quintiles of dietary riboflavin intakes, from >2.1 in Q1 to <1.1 mg/d in Q5.. Females in LMICs had much higher rates of riboflavin deficiency: Malaysia (72%); Cambodia (82%); and Uganda (90%). In British children (n = 307), riboflavin status declined markedly with age, with median EGRac values of 1.25 (1.20, 1.28) at age 1-5 y compared with 1.40 (1.35, 1.44) at 15-17 y. In children from LMICs, 39%-75% had riboflavin deficiency, and in Ugandan children aged 5-17 y, median EGRac was 1.77 (1.39, 2.15), corresponding with clinical deficiency signs observed in this cohort. CONCLUSIONS: Riboflavin deficiency is highly prevalent in females and children across many regions worldwide. Given the wide-ranging adverse health consequences of deficiency, population-based strategies to improve riboflavin status in both LMICs and HICs are urgently needed.