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Serum Selenium Concentrations and Diabetes in US Adults: National Health and Nutrition Examination S
Abstract and Introduction
Abstract
Background: Increasing evidence suggests that high selenium levels are associated with diabetes and other cardiometabolic risk factors.
Objectives: We evaluated the association of serum selenium concentrations with fasting plasma glucose, glycosylated hemoglobin levels, and diabetes in the most recently available representative sample of the U.S. population.
Methods: We used a cross-sectional analysis of 917 adults ≥ 40 years of age who had a fasting morning blood sample in the National Health and Nutrition Examination Survey 2003–2004. We evaluated the association of serum selenium, measured by inductively coupled plasma-dynamic reaction cell-mass spectrometry, and diabetes, defined as a self-report of current use of hypoglycemic agents or insulin or as fasting plasma glucose ≥ 126 mg/dL.
Results: Mean serum selenium was 137.1 < g/L. The multivariable adjusted odds ratio [95% confidence interval (CI) ] for diabetes comparing the highest quartile of serum selenium (≥ 147 < g/L) with the lowest (< 124 < g/L) was 7.64 (3.34–17.46). The corresponding average differences (95% CI) in fasting plasma glucose and glycosylated hemoglobin were 9.5 mg/dL (3.4–15.6 mg/dL) and 0.30% (0.14–0.46%), respectively. In spline regression models, the prevalence of diabetes as well as glucose and glycosylated hemoglobin levels increased with increasing selenium concentrations up to 160 < g/L.
Conclusions: In U.S. adults, high serum selenium concentrations were associated with higher prevalence of diabetes and higher fasting plasma glucose and glycosylated hemoglobin levels. Given high selenium intake in the U.S. population, further research is needed to determine the role of excess selenium levels in the development or the progression of diabetes.
Introduction
Most Americans have selenium intake ranging from 60 to 220 < g/day (Combs 2001), well above the recommended dietary allowance of 55 < g/day (Institute of Medicine and Panel on Dietary Antioxidants and Related Compounds 2000; Rayman 2008). This high level of intake, particularly compared with other countries, is attributable to the high soil content of selenium in several areas of the United States, which is eventually incorporated in the food chain (Rayman 2008). Although selenium is required for adequate function of glutathione peroxidase and other selenoproteins, the risk of selenium deficiency in the U.S. general population is negligible. Additional selenium intake at high intake levels does not increase glutathione peroxidase synthesis or activity, but rather increases plasma selenium concentration by the nonspecific incorporation of selenomethionine into plasma proteins (Institute of Medicine and Panel on Dietary Antioxidants and Related Compounds 2000), with unknown health effects.
Bleys et al. (2007) reported a positive association between serum selenium concentrations and the prevalence of diabetes among participants in the Third National Health and Nutrition Examination Survey (NHANES III). Stranges et al. (2007) reported an increased risk of diabetes among participants randomized to long-term selenium supplementation (200 < g/day) in the Nutritional Prevention of Cancer (NPC) trial. Recently, the Selenium and Vitamin E Cancer Prevention Trial (SELECT), a mega-trial aimed to evaluate the efficacy of selenium in preventing prostate cancer, was prematurely stopped by the data and safety monitoring committee because of lack of benefit on the primary end point and the possibility of an increased risk of diabetes in the selenium-only arm (Lippman et al. 2009). Additionally, high selenium status has been linked with hypercholesterolemia (Bleys et al. 2008b) and hypertension (Laclaustra et al. 2009) in the U.S. population.
Because there is a narrow range between selenium intake levels required for selenoprotein synthesis and toxic levels (Institute of Medicine and Panel on Dietary Antioxidants and Related Compounds 2000), these findings raise concerns of possible adverse cardiometabolic effects of high selenium exposure, at least in selenium-replete populations such as the United States. NHANES III and the NPC trial, however, were conducted during the 1980s and early 1990s, and there are no recent data on the association of serum selenium levels with diabetes in the United States. The objective of this study was to evaluate the association of serum selenium concentrations with the prevalence of diabetes using recently available NHANES data collected in 2003–2004. Moreover, we also evaluated the association between serum selenium levels with fasting plasma glucose and glycosylated hemoglobin levels, biomarkers not previously considered.
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