Selenium is a mineral that’s naturally found in many foods, added to numerous others, and regularly consumed as a dietary supplement.

Some people claim that selenium deficiency is rampant, and that correcting this common malady is the key to warding off a long list of diseases.

Others say that selenium deficiency is wildly overblown, and that we should be more concerned with eating too much selenium, not too little.

Who’s right?

The long story short is, getting adequate selenium from your diet is essential for your health, though getting too much can also be dangerous.

If you want to know the ins and out of how selenium can benefit you, and how much you should eat to optimize your health, keep reading!

What Is Selenium?

Selenium is an essential micronutrient found in foods such as Brazil nuts, bread, grains, meat, poultry, fish, and eggs. The reason it’s “essential” is because you must get selenium from your diet.

Selenium binds to the amino acid cysteine in the body to form selenoproteins. Selenoproteins play a vital role in numerous bodily processes, such as thyroid and immune function, reproductive health, and DNA synthesis.

Until 1957, scientists believed that selenium was toxic to humans, and that it should be avoided completely. We now know that selenium is an important nutrient that’s vital to our health. 

That said, it is possible to consume too much selenium (especially if you eat a lot of high-selenium foods), which is why it’s important to moderate your selenium intake.

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Selenium Benefits

Some research shows that getting enough selenium may help . . .

. . . though it’s hard to say how much of a role selenium plays in these different ailments, as many of the studies are observational (which can show correlation but not causation), or have been disputed by subsequent research.

What research has shown more clearly, however, is that getting adequate amounts of selenium is linked with . . .

  • Reduced chronic inflammation 
  • Reduced oxidative stress
  • Improved thyroid function
  • Improved immune function
  • Improved mood and reduced anxiety
  • Improved cardiovascular health

Let’s take a look at each of these in more detail now.

Selenium and Inflammation

Having high levels of chronic inflammation is associated with the development of numerous health conditions, such as cancer, heart disease, diabetes, and obesity.

Selenium inhibits the activation and release of the most inflammatory proteins in the body, such as interleukin-6, interleukin-8, TNF-alpha, and NF-kappaB, and has been shown to reduce levels of an important marker of inflammation called C-reactive protein (CRP).

Selenium and Oxidative Stress

Free radicals are molecules produced either in the body as part of metabolism, or as a result of being exposed to carcinogens in the environment. An excess of free radicals in the body leads to what is known as oxidative stress, which can increase your risk of numerous diseases, including cardiovascular disease, cataracts, and cancer.

Research shows that antioxidants such as selenium help to neutralize the damage done by free radicals, and protect your body from oxidative stress. 

Selenium and Thyroid Function

One of the main functions of the thyroid gland is to release hormones that regulate your metabolism. If the production of these hormones is disrupted in any way, many of the body’s functions, including heart rate, breathing rate, and digestion may be affected. 

The thyroid gland contains more selenium than any other organ in the body. If you are deficient in selenium, it’s likely your thyroid’s function will be impaired, and you may develop a thyroid disorder, such as Hashimoto’s disease, Grave’s disease, hypothyroidism, autoimmune thyroiditis, or enlarged thyroid (goiter).

Selenium and Immune Function

Maintaining a healthy immune system helps to ward off pathogens like viruses, bacteria, and protozoa, and reduces the risk of getting sick. 

Research shows that having low levels of selenium is associated with compromised immune function, whereas having good levels of selenium has been shown to have a positive effect on

antiviral immunity, autoimmunity, sepsis, allergic asthma, and chronic inflammatory disorders.

Selenium and Cognitive and Mental Health

Studies show there’s a link between having low levels of selenium and cognitive decline.

While it’s still unclear what effect supplementing with selenium has on cognitive health, there’s reason to believe that getting adequate levels of selenium over the long-term is better for staving off cognitive impairment than not getting enough. 

Research also shows that low levels of selenium are associated with anxiety, depression, and

hostility, and that supplementing with selenium can markedly improve symptoms. 

Selenium and Cardiovascular Health

A meta-analysis of 25 observational studies found that people with low selenium levels had a higher risk of coronary heart disease.

Research shows that selenium supplementation decreases levels of CRP, and increases levels of the powerful antioxidant glutathione peroxidase (GSH-PX), which likely minimizes the oxidative stress and inflammation that can lead to heart disease.

Selenium Side Effects

There are no side effects associated with selenium when taken at the correct dosage.

However, getting excessive amounts of selenium, whether from your diet or from a supplement, can be harmful.

Some of the dangers of getting excess selenium include . . .

  • Possible increased risk of diabetes in men
  • Possible decreased levels of lower active thyroid hormone (T3) in men 
  • Possible increased levels of total cholesterol, LDL cholesterol, HDL cholesterol, triacylglycerols, apo B, and apo A-I.

. . . and some of the symptoms of selenium toxicity (very high levels of selenium) include . . .

  • Stomach pain
  • Fatigue
  • Joint pain
  • Skin discoloration or skin lesions
  • Brittle nails (with white spots and longitudinal streaks on the surface)
  • Alopecia (hair loss)
  • Garlic breath
  • Nausea or vomiting
  • Diarrhea
  • Pulmonary edema
  • Tremors or muscle spasms
  • Restlessness 
  • Confusion and delirium
  • Coma

The Tolerable Upper Intake Level (TUL) for selenium in adults is 400 mcg per day. In other words, most adults can consume up to 400 mcg of selenium per day before they experience any negative side effects.

The recommended dietary allowance (RDA) of selenium is 55 mcg per day, though studies looking at the effects of selenium supplementation routinely use much higher doses than this.

People’s average selenium intake is highly variable and largely depends on the selenium content of the soil that your food was grown in. As consuming too much is harmful, it’s best to err on the side of caution and aim for around 55 mcg per day (and no more than 400).

FAQ #2: What are the best food sources of selenium?

The best food sources of selenium are:

  • Brazil nuts (544 mcg per one-ounce serving)
  • Tuna (92 mcg per three-ounce serving)
  • Halibut (47 mcg per three-ounce serving)
  • Sardines (45 mcg per three-ounce serving)
  • Ham (42 mcg per three-ounce serving)
  • Shrimp (40 mcg per three-ounce serving)
  • Beef steak (33 mcg per three-ounce serving)
  • Turkey (31 mcg per three-ounce serving)
  • Chicken (22 mcg per three-ounce serving)
  • Cottage cheese (20 mcg per cup)
  • Brown rice (19 mcg per cup)
  • Egg (15 mcg per egg)
  • Whole-wheat bread (13 mcg per slice)
  • Baked beans (13 mcg per cup)
  • Oatmeal (13 mcg per cup)

FAQ #3: What is the best selenium supplement?

One selenium supplement is much like any other, so it’s impossible to say that one selenium supplement is clearly “better” than another. 

That said, given that most people can get much of the selenium they need from food, you don’t consume too much selenium from supplements. Many commercially available selenium supplements contain 200 mcg or more of selenium per serving, which is far more than most people need. 

That’s why we included a more reasonable (and evidence-based) dose of just 25 mcg of selenium in each serving of our sport multivitamin, Triumph. When combined with a healthy diet, this is enough to ensure you don’t become deficient or consume too much. 

Triumph is a sport multivitamin that enhances health, performance, and mood, and reduces stress, fatigue, and anxiety.

In addition to 25 mcg of selenium per serving, it contains clinically effective doses of 31 other ingredients designed to improve your mental and physical health and performance, and boost your resistance to stress, dysfunction, and disease.

So, if you want a healthier, happier body, try Triumph today.

+ Scientific References