Serum selenium and serum lipids in US adults

Abstract

Background: Selenium, an essential micronutrient, has received considerable attention for its antioxidant properties. In addition, selenium may affect several cardiometabolic risk factors, such as glucose homeostasis and lipid concentrations. However, the effects of selenium intake on the lipid profile in selenium-replete populations, such as the United States, are largely unknown.

Objective: We examined the relation of serum selenium concentrations with serum lipids in a representative sample of US adults.

Design: This was a cross-sectional analysis of 5452 men and women aged >/= 20 y participating in the third National Health and Nutrition Examination survey. Serum selenium was measured by atomic absorption spectrometry.

Results: The multivariable adjusted differences in total cholesterol, LDL cholesterol, HDL cholesterol, apolipoprotein B (apo B), and apolipoprotein A-I (apo A-I) comparing the highest with the lowest quartile of serum selenium were 16.6 mg/dL (95% CI: 11.6, 21.4 mg/dL), 10.9 mg/dL (95% CI: 6.4, 15.4 mg/dL), 3.2 mg/dL (95% CI: 1.6, 5.0 mg/dL), 8.9 mg/dL (95% CI: 5.6, 12.2 mg/dL), and 6.9 mg/dL (95% CI: 1.7, 12.1 mg/dL), respectively. Participants in the highest quartile of serum selenium had 10% higher concentrations of triacylglycerols than did participants in the lowest quartile (ratio of triacylglycerol concentrations: 1.10; 95% CI: 1.05, 1.17). The difference in the ratios of LDL cholesterol to HDL cholesterol and apo B to apo A-I that compared the highest with the lowest selenium quartiles were 0.11 (95% CI: -0.02, 0.25) and 0.03 (95% CI: 0.00, 0.06), respectively.

Conclusion: Elevated serum selenium was associated with elevated serum concentrations of total cholesterol, LDL cholesterol, HDL cholesterol, triacylglycerols, apo B, and apo A-I among US adults, a selenium-replete population. Experimental studies are needed to determine cause and effect relations and the potential mechanisms underlying these associations.

FIGURE 1

Serum lipid and lipoprotein concentrations by serum selenium concentrations, Third National Health and Nutrition Examination Survey. Dose-response lines are based on restricted cubic spline transformations with 4 knots. Results were adjusted for education, family income, postmenopausal status for women, cigarette smoking, serum cotinine, alcohol consumption, physical activity, body mass index, cholesterol-lowering medication use, vitamin-mineral supplement use, glomerular filtration rate, C-reactive protein, diabetes mellitus, thyroid-stimulating hormone, and thyroxine.

FIGURE 2

Differences in serum concentrations of LDL cholesterol and HDL cholesterol comparing the 80th (137.7 ng/mL) with the 20th (111.4 ng/mL) percentile of the serum selenium distribution. Differences (95% CI in parentheses) in concentrations of serum LDL cholesterol and HDL cholesterol were derived from multiple linear regression models that included serum selenium concentrations as a continuous variable. Differences were adjusted for age, sex, race-ethnicity, education, family income, postmenopausal status for women, cigarette smoking, serum cotinine, alcohol consumption, physical activity, body mass index, cholesterol-lowering medication use, vitamin-mineral supplement use, glomerular filtration rate, C-reactive protein, diabetes mellitus, thyroid-stimulating hormone, and thyroxine. The area of each square is proportional to the inverse of the variance. Horizontal lines represent 95% CIs. None of the P values for the interactions was statistically significant at the 0.05 level, except for the interaction of serum selenium and sex on serum HDL cholesterol (P < 0.001) and the interaction of serum selenium and race on serum HDL cholesterol (P = 0.03). Although we used a comparison between the 80th and 20th percentiles, the statistical significance of these analyses would be the same if we had used other percentiles for comparison.

FIGURE 3

Ratios of serum triacylglycerol concentrations comparing the 80th (137.7 ng/mL) with the 20th (111.4 ng/mL) percentile of the serum selenium distribution. Ratios (95% CI in parentheses) of triacylglycerol concentrations were derived from multiple linear regression models that included serum selenium concentrations as a continuous variable. Ratios were adjusted for age, sex, race-ethnicity, education, family income, postmenopausal status for women, cigarette smoking, serum cotinine, alcohol consumption, physical activity, body mass index, cholesterol-lowering medication use, vitamin-mineral supplement use, glomerular filtration rate, C-reactive protein, diabetes mellitus, thyroid-stimulating hormone, and thyroxine. The area of each square is proportional to the inverse of the variance. Horizontal lines represent 95% CIs. None of the P values for the interactions was statistically significant at the 0.05 level. Although we used a comparison between the 80th and 20th percentiles, the statistical significance of these analyses would be the same if we had used other percentiles for comparison.