Selenium

As a trace mineral, selenium is only needed in small amounts in the body. The body uses it to make certain antioxidants, which help stop the cells of the body from being damaged. As a result, selenium can help treat or prevent several health conditions, such as heart disease, HIV or AIDS, and arthritis.

 

What Is Selenium?

Selenium is a trace mineral. This means that it is essential for human nutrition, but it is only needed in tiny amounts. Most people in the United States get enough of it through dietary means -- mostly through plant sources. Having a deficiency is rare in the United States, but it may be more common in other parts of the world where levels in the soil and, therefore, in the plants are low. Selenium is claimed to be useful for treating or preventing various medical conditions, such as HIV or AIDS, heart disease, and arthritis.
 
(Click Benefits of Selenium for more information.)
 

How Does Selenium Work?

The body needs a small amount of selenium. Too little or too much can cause problems. The trace mineral is used by the body to make certain antioxidants, which help to fight free-radical damage to the cells. However, high selenium levels can actually have the opposite effect, encouraging free-radical damage.
 
The mineral also plays a role in the regulation of thyroid hormones and may help to regulate the immune system.
 

Is It Effective?

Early research suggests that it may be effective for a number of different uses (see Does Selenium Work? for more information).
 

Dosing Information

Although an RDA (Recommended Dietary Allowance) has been determined for the trace mineral, it can be difficult to recommend a standard dose because the dietary intake can vary.
 
(Click Selenium Dosage for more information.)
 

Are There Side Effects?

Normal intakes of selenium do not seem to cause side effects for most people. However, a high intake can cause serious, even life-threatening, problems.
 
(Click Selenium Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
 

Drug Interactions With Selenium

Selenium can potentially interact with several medications (see Selenium Drug Interactions).
 

Safety Issues

Even though normal intakes are safe and necessary, higher intakes can cause serious problems. Some people are more likely than others to experience problems. Therefore, you should talk with your healthcare provider prior to taking selenium if you have:
 
  • An underactive thyroid (hypothyroidism)
  • Male infertility
  • Skin cancer (or a history of skin cancer)
  • Any allergies, including allergies to foods, dyes, or preservatives.
     
Also, let your healthcare provider know if you are:
 
Make sure to tell your healthcare provider about any other medications you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
 
(Click Is Selenium Safe? for more information, including any available warnings and precautions.)
 

What If I Take an Overdose of Selenium?

An overdose can cause serious problems, sometimes resulting in death. This is possible if you take too much all at once or if you take too much on a daily basis. If you think you may have taken too much, seek immediate medical attention.
 
(Click Selenium Overdose for more information.)
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;