Associations between Urinary and Dietary Selenium and Blood Metabolic Parameters in a Healthy Northern Italy Population

Abstract

Selenium is both an essential nutrient and a highly toxic element, depending on its dose and chemical forms. We aimed to quantify urinary selenium excretion and dietary selenium intake in 137 healthy non-smoking blood donors living in the northern Italian province of Reggio Emilia. We assessed selenium status by determining urinary selenium levels (mean 26.77 µg/L), and by estimating dietary selenium intake (mean 84.09 µg/day) using a validated semi-quantitative food frequency questionnaire. Fasting blood levels of glucose, lipids and thyroid-stimulating hormone were measured using automatized laboratory procedures. Dietary and urinary selenium were correlated (beta coefficient (β) = 0.19). Despite this, the association of the two indicators with health endpoints tended to diverge. Using linear regression analysis adjusted for age, sex, body mass index, cotinine levels and alcohol intake, we observed a positive association between urinary selenium and blood triglyceride (β = 0.14), LDL-cholesterol (β = 0.07) and glucose levels (β = 0.08), and an inverse one with HDL-cholesterol (β = −0.12). Concerning dietary selenium, a slightly positive association could be found with glycemic levels only (β = 0.02), while a negative one emerged for other endpoints. The two selenium indicators showed conflicting and statistically highly imprecise associations with circulating TSH levels. Our findings suggest that higher selenium exposure is adversely associated with blood glucose levels and lipid profile. This is the case even at selenium exposures not exceeding tolerable upper intake levels according to current guidelines.

Gene-environment interaction analysis of redox-related metals and genetic variants with plasma metabolic patterns in a general population from Spain: The Hortega Study

“…The inclusion criteria were limited, however, to studies including only participants with metabolic syndrome. Moreover, our results are largely consistent with a number of cross-sectional studies reporting a positive association between serum Se and LDL cholesterol, particularly in Se-repleted populations [ 14 , 18 , [108] , [109] , [110] ], but also in studies using other Se biomarkers such as urine Se [ 111 ]. Alternatively, two meta-analysis (one of eight cross-sectional studies and another of five clinical trials) did not find an association between Se supplementation and LDL levels [ 106 , 107 ].…”

Association of Urinary and Dietary Selenium and of Serum Selenium Species with Serum Alanine Aminotransferase in a Healthy Italian Population

“…The median and IQR values of the various organic and inorganic selenium species are reported in Table 3. When assessing the association between the different selenium biomarkers used in the study participants, we found a positive association between dietary intake and urinary selenium concentrations, especially above 100 µg of daily selenium intake [45]. The association between total serum and urinary selenium concentration was negative and almost linear, while that with dietary intake was U-shaped, in that it was negative until 90 µg/day and then slightly positive (Figure S1).…”

Selenium Status and Its Antioxidant Role in Metabolic Diseases

“…For long-term Se status, the toenail and hair Se levels are often employed as markers. Se urinary excretion is closely correlated with plasma and serum levels and can be used to monitor recent dietary intake of Se [ 34 , 35 ]. Moreover, bioassays of selenoproteins in different blood fractions may provide more accurate estimates of physiological Se status [ 36 ].…”