Selenium supplementation and health
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Selenium Supplementation and Health: Essential Trace Element Benefits and Risks
Selenium’s Role in Human Health and Disease Prevention
Selenium is an essential trace mineral that plays a key role in human health, mainly through its incorporation into selenoproteins, which have antioxidant, anti-inflammatory, and immune-modulating properties Rayman2012Zhang2023Sun2023. Adequate selenium intake is linked to reduced risks of certain diseases, including digestive system cancers, all-cause mortality, depression, Keshan disease, and Kashin-Beck disease in children Wang2023Sun2023. Selenium is also important for reproductive health and the maintenance of brain function Rayman2012Zhang2023.
Selenium Supplementation: Potential Benefits
Selenium supplementation has shown benefits in specific health conditions, such as improving sperm quality, polycystic ovary syndrome, autoimmune thyroid disease, and some cardiovascular diseases Wang2023Rayman2012Zhang2023+1 MORE. It can also help regulate lipid metabolism and reduce inflammation and oxidative stress, as seen by decreased serum C-reactive protein and increased glutathione peroxidase levels in some studies Wang2023Zhang2023Ju2017+1 MORE. In populations with low baseline selenium status, supplementation may help prevent or treat chronic diseases, including certain cancers, cardiovascular disease, and immune-related disorders Rayman2012Sun2023Hu2021.
Risks and Adverse Effects of Excess Selenium
However, the relationship between selenium status and health is U-shaped: both deficiency and excess can be harmful Rayman2012Sun2023Urbano2025+2 MORE. Supplementation in people with adequate or high selenium levels may increase the risk of type 2 diabetes, non-melanoma skin cancers, and adverse changes in blood lipid profiles, such as increased LDL cholesterol and triglycerides and decreased HDL cholesterol Wang2023Rayman2012Zhang2023+1 MORE. High selenium intake can also be toxic, especially at doses above recommended levels or with certain forms of selenium Urbano2025Rayman2019.
Selenium and Immune Function
While selenium is important for immune cell activation, evidence for supplementation improving immune function in healthy individuals is inconsistent. Most studies show little to no effect on immunoglobulin levels, white blood cell counts, or cytokine levels, with only minor benefits for natural killer cell activity Zhang2023Filippini2022. The overall evidence does not support selenium supplementation beyond recommended dietary intake for immune enhancement in the general population .
Recommendations and Safety Considerations
Given the narrow safety window and the U-shaped dose-response relationship, selenium supplementation should be considered mainly for individuals with proven deficiency or low baseline status Rayman2012Sun2023Urbano2025+1 MORE. For the general population, extra selenium supplementation is not recommended, and supplementation should be discontinued once deficiency is corrected Wang2023Rayman2012Sun2023. The form and dose of selenium, as well as individual genetic and environmental factors, can influence both benefits and risks Rayman2012Rayman2019.
Conclusion
Selenium is vital for health, but both deficiency and excess carry risks. Supplementation can be beneficial for those with low selenium status or specific health conditions, but unnecessary supplementation in those with adequate levels may cause harm. Careful assessment of individual selenium status and adherence to recommended intake levels are essential for maximizing benefits and minimizing risks.
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Most relevant research papers on this topic
Selenium and Selenoproteins in Health
Selenium supplementation can help regulate lipid metabolism, maintain immune function, and alleviate cardiovascular diseases, but its effect on cancer risk remains unclear and its relationship with type 2 diabetes is complex.
Selenium and immune function: a systematic review and meta-analysis of experimental human studies.
Selenium supplementation shows inconsistent and heterogeneous effects on immune function, with no clear need to supplement beyond recommended dietary intake for beneficial effects.
The effect of selenium supplementation on coronary heart disease: A systematic review and meta-analysis of randomized controlled trials.
Selenium supplementation can reduce inflammation and oxidative stress in coronary heart disease, but it does not reduce mortality or improve lipid status.
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