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Selenium Supplements Review

Choose the Best Selenium Supplement. Find Out If You Need Selenium and Which Supplement Is Our Top Pick.

Latest Update
Take These When Using Cipro?
Tod Cooperman, M.D.

Medically reviewed and edited by Tod Cooperman, M.D.

 
Latest Update May 21, 2026 ⓘ
Selenium Supplements Reviewed by ConsumerLab.com
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Results of ConsumerLab.com Testing of SELENIUM SUPPLEMENTS

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Quick Summary

  • What is selenium?

    Selenium is an essential mineral (see What It Is). Only trace amounts of selenium are needed and deficiency is rare in the U.S. and Canada due to selenium occurring in foods such as grains and meats, but is more prevalent in countries with low levels of selenium in soil (see From Food).

  • What are the health benefits of selenium?

    Selenium is important for proper immune and thyroid function. There is mixed evidence as to whether supplementing with selenium can help reduce the risk of cancer: It may only help those deficient in selenium, while it may be potentially harmful for others (see What It Does).

  • How much selenium should I take?

    The daily requirement for selenium is just 55 micrograms (mcg) for most adults and a bit higher for women who are pregnant or lactating. Dosage in supplements generally ranges from 100 to 200 mcg (see What to Consider When Using). The tolerable upper intake level is 400 mcg daily, above which there is increased risk of adverse effects such as hair and nail brittleness (see Concerns and Cautions).

  • Best selenium supplement?

    As shown in comparison graph and Results Table the cost to obtain 200 mcg of selenium ranged from 3 cents to $1.39. Among supplements which passed testing, we identified our Top Pick, providing a highly absorbable form of selenium at low cost.
Products tested in 2019

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Selenium supplement brands compared in this review

View Larger Image 365 [Whole Foods] Selenium 100 mcg

365 [Whole Foods] Selenium 100 mcg

View Larger Image Allergy Research Group Selenium Solution

Allergy Research Group Selenium Solution

View Larger Image GNC Selenium 200 mcg

GNC Selenium 200 mcg

View Larger Image Life Extension Super Selenium Complex

Life Extension Super Selenium Complex

View Larger Image Mega Food Selenium

Mega Food Selenium

View Larger Image Natural Factors Selenium 200 mcg

Natural Factors Selenium 200 mcg

View Larger Image Nature's Way Selenium 200 mcg

Nature's Way Selenium 200 mcg

View Larger Image NOW Selenium 200 mcg

NOW Selenium 200 mcg

View Larger Image Puritan's Pride High Potency Selenium 200 mcg

Puritan's Pride High Potency Selenium 200 mcg

View Larger Image Spring Valley Selenium 200 mcg

Spring Valley Selenium 200 mcg

View Larger Image Swanson Ultra SelenoExcell

Swanson Ultra SelenoExcell

View Larger Image The Vitamin Shoppe Selenium

The Vitamin Shoppe Selenium

You must be a member to get the full test results along with ConsumerLab.com recommendations and quality ratings. You will get results for 10 selenium supplements selected by ConsumerLab.com and two others that passed testing in the voluntary Quality Certification Program.  In this comprehensive review, you'll discover:
  • Which selenium supplements passed or failed testing
  • ConsumerLab's Top Pick among products
  • Differences among forms of selenium (e.g., selenium from yeast, selenomethionine, Se-methyl-L-selenocysteine, and selenite)
  • Which foods are rich in selenium 
  • The causes and symptoms of selenium deficiency
  • How much selenium you need based on age and gender
  • How selenium seems to affect the risk of various cancers -- positively and negatively, and other conditions
  • Safety concerns and potential side-effects of selenium supplements

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Latest Clinical Research Updates for Selenium Supplements

Take These When Using Cipro?

April 24, 2025
Antibiotics known as fluoroquinolones (such as "Cipro") may cause tendonitis (particularly of the Achilles tendon) weeks after use. A preliminary study suggests that taking vitamin E and selenium supplements may slightly reduce resulting symptoms. For details, see the What It Does section of our Vitamin E Review. Also see our Top Picks for vitamin E and selenium.

Selenium Glycinate

December 16, 2024
Is selenium glycinate more bioavailable than other forms of selenium? Find out in the What To Consider When Buying section of our Selenium Supplements Review, which includes our Top Picks for selenium.

Selenium Deficiency In Vegetarians

April 12, 2024
Are vegans and vegetarians likely to be deficient in selenium? Depends on where you live. Learn more in our Selenium Supplements Review, which includes our Top Picks among selenium supplements.

Also see: Top 8 vitamins and nutrients for vegetarians and vegans.

Selenium & Hair

August 22, 2023

Although an essential nutrient, very high intake of selenium can cause hair to fall out, and a recent case report highlighted the need to consider how much selenium one gets from foods before supplementing with selenium. Get the details in the Concerns and Cautions section of our Selenium Supplements Review.

Also see our article about hair growth to find out which other supplements can cause hair to fall out.

Diabetes Risk With Selenium

March 03, 2021
High intake of selenium from the diet or supplements has been associated with increased risk of type 2 diabetes. Get the details in the Concerns and Cautions section of our Selenium Supplements Review.

Selenium & COVID-19

July 18, 2020
Selenium-deficient people were more likely to die from COVID-19 than those who were not deficient according to a recent study. For details, see the What It Does section of the Selenium Supplements Review. Also see our Top Pick for selenium.

Risk With Too Much Selenium

February 21, 2018
Taking too much selenium was found to increase the risk of death in a newly published study. How much is too much? Get the details in the Concerns and Cautions section of the Selenium Supplements Review.

Vitamin E/Selenium & Alzheimer's

March 29, 2017
A long-term study among men in the U.S. found that giving high doses of vitamin E and/or selenium did not significantly affect their risk of developing dementia. The study was part of a larger study which found that these supplements increased the risk of prostate cancer, type 2 diabetes, hair loss, and dermatitis. For details, see the "Alzheimer's disease/dementia" section of the Selenium Supplements Review >>

Toxin in Algae Supplements

March 28, 2017
Some Spirulina supplements and many A. flos-aquae supplements were found to be contaminated with microcystin toxin — a liver toxin, according to a recently published study. For details, see the "Concerns and Cautions" section of the Greens and Whole Food Supplements Review >>

Selenium and Ovarian Cancer

February 18, 2017
A recent study found that women with the highest intakes of selenium from supplements had a much lower risk of ovarian cancer than those not getting selenium from supplements. Get the details in the "What It Does" section of the Selenium Supplements Review (which includes our tests of products) >>

Selenium and Prostate Cancer

March 01, 2015
A new study suggests that men who have prostate cancer should not take supplements providing high-dose selenium. Earlier research has similarly advised against high-dose selenium for people with already adequate selenium intake. For details and more about selenium, see the Selenium Supplements Review >> 

Can Vitamin E and/or Selenium Help Prevent Cataracts?

September 19, 2014
A study in older men in the U.S. found that taking large daily doses of vitamin E and/or selenium did not significantly reduce the risk of developing cataracts. But could the dose have been too high to be helpful? Other research has shown that "less is more" when it comes to antioxidant supplementation for cataracts. For more information, see the updates to the Vitamin E Supplements Review and the Selenium Supplements Review >> 

Vitamin E, Selenium Can Increase Cancer Risk

February 27, 2014
In some men, taking high doses of vitamin E or selenium may double the risk of developing high-grade prostate cancer, according to a recent analysis. For details, including the dose, see the updates to the Vitamin E Supplements Review >> and the Selenium Supplements Review >>   

Antioxidants: Too Much of a Good Thing?

August 25, 2013
A new, long-term study of Americans found the risk of dying over the course of the study (about 14 years) was lowest when antioxidant levels in the blood were above the lowest levels (the bottom 20% of the population). However, for people in the top 20% of blood levels for vitamins A and E, the risk of death increased compared to people with moderate levels. For selenium and beta-carotene, there was no significant difference in the death rate between moderate and high levels, although for vitamin C some additional benefit was seen at high, but not the highest, levels.
 
The results suggest that antioxidant supplements may be useful for those who are nutritionally deficient, but, as noted by the researchers, "beyond a certain threshold, higher levels do not lead to additional benefit, and may potentially be toxic." More details (including specific serum levels) are found in the linked updates to the following reviews, which include our test results and quality ratings of products:
 
 
  
  
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Tested through CL's Quality Certification Program prior to, or after initial posting of this Product Review.