The Study
Selenium Status Associates with Thyroid Hormone and Thyroid Dysfunction in Older Chinese Adults
This study looked at people's selenium levels and their thyroid health at the same time, like taking a photo. It found that people with more selenium often had different thyroid levels, but we don't know if selenium changed their thyroid or if their thyroid changed their selenium. It's like noticing people who eat more ice cream also have more sunburns — but that doesn't mean ice cream causes sunburns.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
This study looked at older people in China to see if how much selenium they have in their body affects their thyroid hormones.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1These results suggest selenium might help prevent underactive thyroid but could increase risk of overactive thyroid in older adults — important because thyroid problems are common in aging.
- 2People with more selenium in their blood had lower TSH and higher T3 and T4 hormones.
- 3Those with the most selenium in blood were 86% less likely to have underactive thyroid.
- 4But those with medium selenium in fingernails were over 4 times more likely to have overactive thyroid.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Biological trace element research
Year
2024
Authors
Feng Li, Liqin Su, Ran Shao, Jiao Luo, Yi Chen, Yifeng Huang, Ming-Rui Wei, Jiliang Zhang, Yumei Gao, Kui Ma, Xiyao Liu, Weihao Xi, Sujuan Gao
Related Content
Claims (6)
Low selenium levels are linked to a higher ratio of free T4 to free T3 in the blood, and restoring selenium levels returns this ratio to normal.
In older Chinese adults aged 65 and older, higher selenium levels in the blood and fingernails are linked to lower thyroid-stimulating hormone levels and higher levels of active thyroid hormones.
In older Chinese adults, blood selenium levels are not linked to total thyroxine levels, but are linked to other thyroid hormones, suggesting selenium affects how these hormones are converted or cleared from the body, not how much total thyroxine is made.
Older Chinese adults with higher selenium levels in their blood have a lower chance of developing hypothyroidism compared to those with the lowest selenium levels.
Older Chinese adults with higher selenium levels in their fingernails have a more than fourfold higher rate of hyperthyroidism compared to those with the lowest selenium levels, based on adjusted statistical analysis.
In older Chinese adults, the level of selenium in fingernails closely matches the level of selenium in the blood, indicating that fingernail selenium levels can be used to estimate recent selenium intake.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.