Selenium is a trace mineral, acquired in small amounts from our diets and essential to good health.  The selenium content of food depends on the selenium content in the soil in which it is grown. Both too little and too much selenium have adverse effects on health.  

What is Selenium?

Selenium is an essential mineral, indispensable to a whole series of vital proteins called selenoproteins, of which there are 25 different selenoproteins in humans.  It is available as a dietary supplement 

What do you need Selenium for?

Selenium helps your body with:

  • Antioxidant defences – one of the selenoproteins found in humans is the important enzyme glutanthione peroxidases, which helps to protect against cellular damage caused by oxidative stress.

  • To fight infections – maintaining a strong immune system.

  • Thyroid hormone function.

  • Fertility.

How do I measure my Selenium levels?

You can check your selenium levels with a venous blood draw by a phlebotomist and you may wish to consult your doctor / medical professional about your results.

This test will measure your levels of the mineral against the reference ranges of:

  • Very Low – Under <80 mcg/L

  • Low – Between 80-99 mcg/L

  • Sub-Optimal  – Between 100-114 mcg/L

  • Optimal range – Between 115-135 mcg/L

  • Higher end of optimal – Between 136-150 mcg/L

  • Excess – Over >150 mcg/L

Selenium levels around 115-135 (micrograms per serving) mcg/L is considered optimal for health in adults.

If you are not within an optimal range of selenium levels in your body, it is important to understand what could be causing this and what you can do to adjust your levels for better health.

What can influence my Selenium levels? 

  • Geographical location - Selenium concentrations in foods vary widely by geographical location according to soil selenium content.  Consequently selenium intake in the US is ample, whereas the intake for many European countries including the UK is relatively low.

  • Dietary pattern -  vegetarian and vegan diets are associated with lower selenium intake.

What can I do to impact my Selenium levels?

There are 2 main ways you can impact your selenium levels for optimal health: 

  • Food sources –Increase selenium-rich foods into your diet: fish; shellfish; meat; organ meats (liver and kidney); brazil nuts; garlic; onions; broccoli; selenium-enriched mushrooms; high-selenium eggs.

  • Appropriate Selenium supplement.

There are some specific ways you can optimise your selenium intake, according to your levels of selenium micrograms per serving:

  • Very Low – Under <80 mcg/L.  We recommend taking a selenium supplement that provides 100mcg per day to accompany the addition of more selenium-rich foods into your diet (please see above). After 3 months, you can retest your selenium level and adjust accordingly. 

  • Low – Between 80-99 mcg/L. We recommend taking a selenium supplement that provides 50mcg per day to accompany the addition of more selenium-rich foods into your diet (please see above). After 3 months, you can retest your selenium level and adjust accordingly.  

  • Sub-Optimal range – Between 100 - 114 mcg/L. To optimise your selenium status we recommend including more selenium-rich foods into your diet (please see above) and  retesting your selenium levels after 3 months.  

  • Optimal – Between 115-135 mcg/L.  Your current diet and supplement intake is optimising Selenium levels. Keep retesting every 3 months to ensure you are maintaining a healthy status of this essential mineral. 

  • Higher end of Optimal - Between 136-150 mcg/L.  We do not recommend any additional selenium in supplement form. Retest your selenium status in 3 months time.

  • Excess – Over >150 mcg/L. Your selenium levels could be too high. Unless medically prescribed, please stop or reduce selenium-containing supplements., reduce intake of foods known to be particularly high in selenium (e.g.g Brazil nuts), and retest your selenium status in 3 months. 

Recommended Selenium supplement

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