Selenium speciation in human serum and its implications for epidemiologic research: a cross-sectional study

Area of Science:

• Biochemistry
• Environmental Health
• Analytical Chemistry

Background:

• Observational studies on selenium and human health, especially cancer risk, show inconsistent results.
• Randomized trials suggest null or adverse effects of selenium, possibly due to inadequate exposure assessment in prior studies.
• Measuring total selenium content overlooks the varying toxicological and nutritional properties of different selenium chemical forms (species).

Purpose of the Study:

• To analyze the distribution of organic and inorganic selenium species in human serum.
• To investigate correlations between selenium species and demographic factors, lifestyle, and storage duration.
• To assess the relationship between total serum selenium and specific selenium species.

Main Methods:

• Serum samples from 50 individuals (35-70 years) in Modena, Italy, were analyzed.
• High-performance liquid chromatography coupled with inductively coupled plasma dynamic reaction cell mass spectrometry (HPLC-ICPDRC-MS) was used for selenium speciation.
• Multivariate analysis was employed to adjust for potential confounders.

Main Results:

• Serum selenium was predominantly organic, but inorganic forms were higher than anticipated.
• Organic selenium forms increased with dietary supplement use and decreased in smokers.
• Sample storage duration significantly impacted selenium speciation, increasing inorganic and decreasing organic forms over time.
• Total serum selenium correlated with albumin-bound selenium and specific organic species in males, but weakly with other forms.

Conclusions:

• Inadequate exposure assessment based on total selenium content may lead to misclassification in epidemiological studies.
• The specific chemical forms of selenium are critical for accurate health risk assessment.
• Proper sample handling and storage conditions are vital for reliable selenium speciation analysis.