Best Selenium Supplements

Updated January 2021
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BestReviews spends thousands of hours researching, analyzing, and testing products to recommend the best picks for most consumers. We only make money if you purchase a product through our links, and all opinions about the products are our own. Read more  
BestReviews spends thousands of hours researching, analyzing, and testing products to recommend the best picks for most consumers. We buy all products with our own funds, and we never accept free products from manufacturers.Read more 
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How we decided

We purchase every product we review with our own funds — we never accept anything from product manufacturers.

30 Models Considered
8 Hours Researched
3 Experts Interviewed
113 Consumers Consulted
Zero products received from manufacturers.

We purchase every product we review with our own funds — we never accept anything from product manufacturers.

Buying guide for best selenium supplements

Selenium is a trace mineral that helps to promote proper thyroid function (which is important if you are trying to lose or maintain a healthy weight) and prevent free-radical damage to cells. Most American diets contain an adequate amount of selenium from foods such as fish, meat, and eggs. But if you know you have a selenium deficiency (it’s best to check with your doctor first), adding a selenium supplement to your daily routine is essential.

You must choose yours carefully though. Some forms of selenium are better absorbed than others and some supplements may set off food allergies, so it's important that you know what to look for when choosing a daily selenium supplement.

If you want to know more about how to find the purest selenium supplements, what the potential side effects are, and how much you can take, you’re in the right place. Our guide will help you find one that will deliver all the benefits at a good price. When you’re ready to buy, consider one of our recommended brands.

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Selenium is commonly found in Brazil nuts, some fish, legumes, and cereals.

Key considerations

Organic vs. inorganic

Selenium is available in two forms: organic and inorganic. Organic forms include selenomethionine, methylselenocysteine, and selenocysteine, while common inorganic forms are selenite and selenate. While both forms are beneficial, the organic forms are superior because they are better retained by the body.

Inorganic forms are quickly excreted once they reach the bloodstream. Check the ingredient list for the specific form of selenium used in the supplement, and try to stick to organic options, if possible.

Daily amount

The amount of selenium you need depends on your age and gender. Most adults should aim for 55 micrograms per day, though pregnant and lactating women should try to consume 60 to 70 micrograms per day. Children under 14 should consume less than 55 micrograms per day. Selenium supplements usually contain much higher doses, with many of them offering 200 micrograms or more. This dosage should be safe for most people, but you should avoid consuming more than 400 micrograms of selenium per day, as this can cause selenium toxicity.

Other ingredients

It's good practice to read any supplement ingredient label thoroughly before you buy it. Selenium supplements usually only contain selenium and a gelatin capsule, but some supplements may also contain proprietary blends, mixing trace amounts of fruits and vegetables or other vitamins together. While these shouldn't harm you, you shouldn't choose a selenium supplement with a proprietary blend just because it appears to offer more helpful ingredients. These are usually present in too small of a quantity to make any real difference.

You should also check the supplement label to be sure there are no common food allergens in the supplement. Yeast is sometimes used in selenium supplements and this could trigger a reaction if you're allergic to yeast. In that case, do some research to find a yeast-free selenium supplement instead. Some manufacturers advertise this on their labels.

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Expert Tip
Some studies suggest that selenium can help with memory loss, heart disease, diabetes, and rheumatoid arthritis. But further studies need to be done to prove a definitive link between selenium supplementation and improvement in these health conditions.


Synthetic vs. whole food supplements

Whole food supplements contain real fruits and vegetables while synthetic supplements are created in a lab. Some people believe that whole food supplements are more natural and deliver better results while others say that synthetic supplements work just as well. It's up to you to decide which you prefer, but you should note that whole food supplements usually contain less selenium per serving than synthetic supplements, so you may need to take more pills to get the same amount.

Capsules per serving

Most selenium supplements only require you to take a single capsule to get your full daily dose of selenium, but it's always smart to check the supplement label to make sure this is the case before you buy it. This is especially important if you don't like taking pills, because you'll be more inclined to actually take the supplement if you only need a single capsule per day.

Size of the capsules

If the selenium supplements are large, you may have more difficulty swallowing them. Try to figure out the size of the capsules before you buy them if you know this is an issue for you. The manufacturer may have a drawing on the label showing the actual size of the capsules, so you’ll know what you're getting before you buy.


Selenium tends to have a strong odor, but some selenium supplements mask this better than others. This is a minor concern compared to the things mentioned above, but it could prevent you from taking the supplement if you're especially sensitive to smells.

Third-party testing

Third-party testing isn't common among supplements, but there are some manufacturers that have their supplements tested by independent agencies to prove that they live up to purity and potency standards. Consider choosing a selenium supplement that is either SP Verified or NSF Certified if you're especially careful about which supplements you consume. The manufacturer should advertise these certifications on the supplement's packaging if it has been tested and approved by one of these agencies.

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Did you know?
Selenomethionine is the form of selenium that's most readily absorbed, with over 90% being absorbed into the bloodstream and used by the body.

Selenium supplements prices

A bottle of selenium supplements ranges between $5 and $20, but if you're trying to find the best value, you shouldn't compare them on their overall cost. Focus on the cost per serving instead. Note that this may be different than the cost per capsule, though these two will most likely be the same for selenium supplements.

To find the cost per serving, look at how many servings the bottle contains and divide the total cost by this number. Most selenium supplements cost between five and seven cents per serving, but some whole-food supplements can run up to 30 cents or more per serving.


  • Always read the manufacturer's instructions and only take the selenium supplement as often as directed.

  • If you experience an upset stomach after taking the selenium supplement, try taking it with food.

  • Talk with your doctor to see if a selenium supplement is a smart addition to your supplementary routine.

  • If you notice side effects, such as brittle hair and nails, nausea, gastrointestinal problems, or nervous system problems, stop taking the selenium supplement immediately and consult your doctor. These could be symptoms of selenium toxicity.

  • If you suspect you're deficient in selenium, your doctor can give you a hair, nail, blood, or urine test that can tell you for sure.

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For your safety
Individuals undergoing kidney dialysis and those with HIV are at a higher risk of selenium deficiency than the general population and should talk with their doctors about taking a selenium supplement.

Other products we considered

The Pure Encapsulations Selenium Supplement contains 200 micrograms of selenomethionine, which is the most readily absorbed form of selenium. These vegan capsules are free from common food allergens, and most users report that they are easy to swallow and that they haven't experienced any unpleasant side effects from taking the supplement. Some customers even claim that regularly taking this supplement has begun to reverse their hair loss and improve their thyroid function.

The NOW Foods Selenium Supplement also contains 200 micrograms of selenomethionine in a gelatin capsule. They're yeast-free, which makes them a great option if you have a yeast allergy and have experienced reactions with other selenium supplements in the past. Users say that the capsules don't have a strong, unpleasant odor like some other selenium supplements and that they're easy to swallow. Most users report seeing results within a few weeks after beginning to take the supplement.

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Children need between 15 and 40 micrograms of selenium per day, and children eight or younger should never consume more than 150 micrograms of selenium per day. Most selenium supplements contain 200 micrograms of selenium per serving, so you should never give these to young children.


Q. How can a selenium supplement help me?
If you are deficient in selenium, taking a supplement can help to improve your thyroid function, and some evidence suggests that selenium supplements may also help to reduce your risk of certain types of cancers. It also works as an antioxidant in your body, protecting your cells against damage from free radicals.

Q. How often should I take a selenium supplement?
Most manufacturers recommend you take their selenium supplements once per day, so this is what you should do unless instructed otherwise by your doctor.

Q. Are selenium supplements safe?
If you take them as directed, they should be safe, but if you're consuming large amounts of selenium through your diet and then you add a selenium supplement, you could take too much and put yourself at risk for selenium toxicity. If you're uncertain whether you should be taking a selenium supplement, talk to your doctor before purchasing one.

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