# Selenium

> Selenium is a trace mineral that plays a critical role in the body, primarily as a component of antioxidant enzymes. These enzymes protect cells from damag

*Source: [https://www.health3.app/biomarkers/selenium](https://www.health3.app/biomarkers/selenium)*

### On This Page

- What it measures
- Measurement units
- Reference ranges
- Health impact
- Related biomarkers
- Scientific references

## What is Selenium?

Selenium is a trace mineral that plays a critical role in the body, primarily as a component of antioxidant enzymes. These enzymes protect cells from damage by free radicals, which are harmful compounds that can contribute to chronic diseases. Selenium is also essential for the proper functioning of the immune system and thyroid gland, influencing metabolism and overall health. Additionally, it supports reproductive health, DNA synthesis, and helps prevent cell damage.

**Selenium deficiency** can lead to several health issues. One of the most notable is Keshan disease, a potentially fatal form of heart disease linked to low selenium levels. Selenium deficiency can also contribute to Kashin-Beck disease, a type of osteoarthropathy. Other potential effects of low selenium include weakened immune response, making the body more susceptible to illness, and hypothyroidism, as selenium is required for the synthesis of thyroid hormones.

**Selenium toxicity**, known as selenosis, can occur from excessive intake, often due to over-supplementation. Symptoms of selenium toxicity include hair and nail loss or brittleness, skin rashes, nausea, fatigue, irritability, and nervous system abnormalities. In severe cases, it can lead to problems with the nervous system, heart, and liver.

**Selenium and iodine work closely in thyroid function**. Selenium is a component of enzymes that help convert thyroid hormones into their active form. While selenium doesn't directly interfere with iodine absorption, a deficiency in selenium can exacerbate the effects of iodine deficiency on thyroid health, and vice versa.

**Factors that support healthy blood selenium levels**:

- Adequate selenium intake can come from a balanced diet that includes foods such as Brazil nuts, seafood, poultry, eggs, and whole grains.
- For people with a thyroid condition, selenium levels are usually monitored in close consultation with a healthcare provider to ensure they are in balance with **iodine levels** for optimal thyroid function.

## Measurement Units

Selenium can be measured in: mg/100mL, mg/dL, mg/L, mg%, nmol/L, µg/L, µg/mL, µmol/L

## Reference Ranges by Age and Gender

Reference ranges represent typical values for healthy individuals. Your healthcare provider must interpret your specific results.

| Age Range | Gender | Unit | Optimal | Normal | Source |
| --- | --- | --- | --- | --- | --- |
| All ages | All genders | µg/L | - | 150 - 160 | Brustbauer, 2014 |

## Related Biomarkers

- [**Vitamin A**](https://www.health3.app/biomarkers/vitamina)

 Vitamin A is one of the factors shown to increase absorption of selenium[Groff, 1995].
- [**Vitamin C**](https://www.health3.app/biomarkers/vitaminc)

 Vitamin C is one of the factors enhancing absorption of selenium[Groff, 1995].

## Related tools

- [**Blood Test Unit Converter**](https://www.health3.app/tools/blood-test-unit-converter)

## Academic References

1. Conner TS, Miller JC, and Richardson AC. Optimal serum selenium concentrations are associated with lower depressive symptoms and negative mood among young adults (2015). *J Nutr*. [DOI: 10.3945/jn.114.198010](https://doi.org/10.3945/jn.114.198010)
2. Brustbauer R, Dam K, Hartmann T, Minear G, and Wimmer I. Selenium levels in patients with autoimmune thyroiditis and controls in lower Austria (2014). *Horm Metab Res*. [DOI: 10.1055/s-0034-1377029](https://doi.org/10.1055/s-0034-1377029)
3. Sies H and Steinbrenner H. Selenium homeostasis and antioxidant selenoproteins in brain: implications for disorders in the central nervous system (2013). *Arch Biochem Biophys*. [DOI: 10.1016/j.abb.2013.02.021](https://doi.org/10.1016/j.abb.2013.02.021)
4. Hoffmann PR, Huang Z, and Rose AH. The role of selenium in inflammation and immunity: from molecular mechanisms to therapeutic opportunities (2012). *Antioxid Redox Signal*. [DOI: 10.1089/ars.2011.4145](https://doi.org/10.1089/ars.2011.4145)
5. Geng T, Guo J, Liu G, Liu L, Lu Q, Pan A, Qiu Z, and Wan Z. Serum selenium concentrations and risk of all-cause and heart disease mortality among individuals with type 2 diabetes (2022). *Am J Clin Nutr*. [DOI: 10.1093/ajcn/nqab241](https://doi.org/10.1093/ajcn/nqab241)
6. Groff JL, Gropper SS, and Hunt SM. Advanced Nutrition and Human Metabolism (1995). *Advanced Nutrition and Human Metabolism*.
7. Zimmermann MB and Köhrle J. The impact of iron and selenium deficiencies on iodine and thyroid metabolism (2002). *Thyroid*. [View Source](https://pubmed.ncbi.nlm.nih.gov/12487769/)
8. Avery JC and Hoffmann PR. Selenium, Selenoproteins, and Immunity (2018). *Nutrients*. [DOI: 10.3390/nu10091203](https://doi.org/10.3390/nu10091203)
9. Bian J, Cao J, Cheng Y, Gao S, Hall KS, Hendrie HC, Ji R, Jin Y, Li P, Liang C, Ma F, Matesan J, Murrell JR, Shen J, Unverzagt FW, and Ying B. Selenium level and cognitive function in rural elderly Chinese (2007). *Am J Epidemiol*. [DOI: 10.1093/aje/kwk073](https://doi.org/10.1093/aje/kwk073)
10. Arthur JR, Beckett GJ., and McKenzie RC. Selenium in the Immune System (2003). *J Nutr*. [DOI: 10.1093/jn/133.5.1457S](https://doi.org/10.1093/jn/133.5.1457S)
11. Carlson BA, Mattmiller SA, and Sordillo LM. Regulation of inflammation by selenium and selenoproteins: impact on eicosanoid biosynthesis (2013). *J Nutr Sci*. [DOI: 10.1017/jns.2013.17](https://doi.org/10.1017/jns.2013.17)
12. Akbaraly TN, Arnaud J, Berr C, Carrière I, Gourlet V, Hininger-Favier I, and Roussel AM. Plasma selenium over time and cognitive decline in the elderly (2007). *Epidemiology*. [DOI: 10.1097/01.ede.0000248202.83695.4e](https://doi.org/10.1097/01.ede.0000248202.83695.4e)
13. Franciscato Cozzolino SM, Jacob-Filho W, Rita Cardoso B, and Silva Bandeira V. Selenium status in elderly: relation to cognitive decline (2014). *J Trace Elem Med Biol*. [DOI: 10.1016/j.jtemb.2014.08.009](https://doi.org/10.1016/j.jtemb.2014.08.009)

### ⚠️ Important Medical Information

This reference page is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Reference ranges vary between laboratories. Always review your lab results with a qualified healthcare provider.