Serum ferritin contributes to racial or geographic disparities in metabolic syndrome in Taiwan

Objectives: Asians and Pacific Islanders have higher circulating serum ferritin (SF) compared with Caucasians but the clinical significance of this is unclear. There is a higher prevalence of metabolic syndrome (MetS) in Taiwanese Indigenous than Han Chinese. Genetically, Indigenous are related to Austronesians and account for 2% of Taiwan's population. We tested the hypothesis that accumulation of Fe in the body contributes to the ethnic/racial disparities in MetS in Taiwan. Design: A population-based, cross-sectional study. Setting: National Nutrition and Health Survey in Taiwan and Penghu Island. Subjects: A total of 2638 healthy adults aged >= 19 years. Three ethnic groups were included. Results: Han Chinese and Indigenous people had comparable levels of SF. Austronesia origin was independently associated with MetS (OR = 2.61, 95% CI 2.02, 3.36). After multiple adjustments, the odds for MetS (OR = 2.49, 95% CI 1.15, 5.28) was significantly higher among Indigenous people in the highest SF tertile compared with those in the lowest tertile. Hakka and Penghu Islanders yielded the lowest risks (OR51.08, 95% CI 0.44, 2.65 and OR = 1.21, 95% CI 0.52, 2.78, respectively). Indigenous people in the highest SF tertile had increased risk for abnormal levels of fasting glucose (OR = 2.34, 95% CI 1.27, 4.29), TAG (OR = 1.94, 95% CI 1.11, 3.39) and HDL-cholesterol (OR = 2.10, 95% CI 1.18, 3.73) than those in the lowest SF tertile. Conclusions: Our results raise the possibility that ethnic/racial differences in body Fe store susceptibility may contribute to racial and geographic disparities in MetS.