Is Selenium a Vitamin? Supplement Benefits with Vitamins E, D, C & A

Is Selenium a vitamin? While this trace mineral is essential for human health, it is not considered to be a vitamin.

People often mistakenly use the term “vitamin” to refer generally to any dietary supplement. However, vitamins refer to a special class of organic compounds that cannot be synthesized in the human body.

Selenium is a chemical element that cannot be synthesized endogenously (within the body), but because it is a mineral it does not qualify as a vitamin.

Use of selenium supplements may support health benefits related to thyroid function, antioxidant status and fertility. This micromineral is commonly used with vitamins – such as Vitamin E and Vitamin D – to promote general well-being.

One of the ways that selenium works is by helping to support the antioxidant effects of Vitamin E (a group of compounds that includes the tocopherols and tocotrienols). These two dietary nutrients will sometimes be combined in supplement products.

Selenium

Essential Mineral

Anti-Oxidant

Immunity

Thyroid Function

How It Works:

• Cofactor for antioxidant enzymes
• Supports thyroid function & metabolism
• Promotes immune function & fertility

Dosage:

Up to 400 mcg per day

Safety:

Rated Likely Safe at Appropriate Dosages

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What is Selenium?

Selenium is a trace chemical element required for good health. But we cannot make this mineral internally and must derive it from food sources.

It is found in small amounts in water and more abundantly in soil. Plants that grow in selenium-rich soils and organisms that eat those plants take up this mineral.

When we eat those plants and animal products, we can obtain trace amounts of this compound. Most people are able to obtain adequate amounts of selenium from their diets, but there may be cases in which supplementation is necessary to achieve optimal intake.

Selenium is important for health because it helps to support the immune system, provide antioxidant defense from free radicals, reduce systemic inflammation and support efficient metabolism.

Multiple animal and in vitro studies have shown that selenium possesses antiviral, pro-fertility, pro-thyroid and anticancer properties. [1]

Some clinical studies also suggest benefits for human health, such as for reversing selenium deficiency symptoms, improving autoimmune thyroiditis and for dyslipidemia (imbalance in blood lipid or cholesterol levels).

Many other purported benefits have been attributed to selenium supplements. However, there is not enough research available to evaluate some of the claims that have been made.

There has been a significant amount of research into the potential effects of combining Selenium with Vitamin E for reducing cancer risk. Study results are mixed with some studies finding benefits and other studies finding no significant changes.

Selenium and Vitamin D for Thyroid

Some dietary supplement protocols used to support thyroid function will combine selenium with Vitamin D.

Vitamin D is sometimes called the “sunshine vitamin” because we synthesize it when we are exposed to the sun’s UV rays. Not getting enough Vitamin D in your body can lead to immune impairment, mood disruption and poor bone quality.

Numerous studies link adequate selenium status and normal thyroid function. A deficiency in Vitamin D can also lead to problems with the thyroid gland.

The thyroid is the body’s master gland that regulates metabolic functions including bodyweight maintenance, body temperature, appetite, sleep and energy production.

According to Dr. Josh Axe, selenium acts as a catalyst for active thyroid hormone synthesis. If your thyroid gland is not able to produce T3 and T4 hormones in adequate amounts, then numerous health problems can develop.

Some of the most common signs of thyroid dysfunction to watch for are weight loss or gain, fatigue, weakness in muscles, sleeping problems and irritability.

Dr. Axe says that selenium acts “as a powerful protector of the thyroid”. He says that selenium moderates ROS (reactive oxygen species) production within the thyroid gland and that it protects this gland from antibodies which increase the risk for thyroid disease. [2]

According to the Natural Medicines Comprehensive Database, selenium supplementation is rated Possibly Effective for autoimmune thyroiditis, a condition marked by inflammation of this endocrine gland.

Autoimmune thyroiditis is also referred to as chronic lymphocytic thyroiditis or Hashimoto’s disease. It occurs when antibodies produced naturally by your body attack your thyroid gland by mistake, resulting in impaired function.

Research shows that taking 200 mcg of selenium with levothyroxine (synthetic thyroxine or T4) reduces thyroid antibodies significantly and improves certain symptoms in patients.

Vitamin D may also improve this condition. A deficiency in Vitamin D is associated with a higher risk of autoimmune thyroid disorders and higher levels of antibodies.

Some natural health practitioners recommend combining these supplements to promote thyroid health. However, there are no research studies available at present to determine whether they are more effective when combined together.

Researchers are also examining selenium’s effects for thyroid cancer and for supporting thyroid function in general.

Research suggests that this mineral can help to reduce inflammation, decrease autoimmune reactions and support immunity in people with thyroid disorders. However, it has not been approved by the FDA as a drug for the prevention or treatment of thyroid disorders.

Selenium and Vitamin E for Cancer

Selenium is a potent antioxidant and is purported to the probability of developing cellular mutations which can lead to cancer. When combined with other antioxidants like Vitamin E, there may be additional benefits.

However, the research on the effects of selenium and cancer risk is unclear and contradictory. Population-based studies suggest a potential association between higher intake of this mineral and lower risk for certain types of cancer. But this result has not been born out in clinical trials.

Chronic selenium deficiency has been linked to mortality from and various types of cancer. According to Dr. Axe, multiple laboratory studies have suggested that selenium is between 50 and 100 times stronger than any other known natural anticarcinogen.

Some studies show that dietary selenium intake is correlated with a reduced risk for developing cancer, lower cancer mortality rates and lower severity of liver, prostate, colorectal and lung cancer.

Some in vitro evidence shows that selenium not only decreases the risk for developing cancer, but also slows down the progression and growth of existing tumors. [3]

Not all studies have found a benefit. The SELECT trial (Selenium and Vitamin E Cancer Prevention Trial) gave 200 mcg dosages per day of this mineral to men for 5.5 years on average. At the end of the trial, there was no significant reduction in risk for prostate cancer.

In the SU.VI.MAX study, patients were given 100 mcg of Selenium with 120 mg Vitamin C, 30 mg Vitamin E (alpha-tocopherol), 6 mg beta-carotene and 20 mg zinc daily for 8 years. The study found no decrease in the risk of prostate cancer across all study participants.

However, in men with normal prostate specific antigen (PSA) levels at the start of the trial, there was a significant 48% reduction in cancer risk.

Another study found that taking selenium with Vitamin E and beta carotene did not have a protective effect against lung cancer development.

More research is needed to determine what effect selenium supplementation has on cancer risk and whether the anti-cancer effects seen in in vitro cell cultures will translate to results in clinical trials.

Selenium for Infertility

Selenium has several important roles in the body related to male fertility. If you do not get enough of this mineral in your diet, it may result in infertility.

Research shows that “A deficiency of dietary selenium leads to immotile, deformed sperm and infertility in rats.” [6] However, increasing your intake of this micromineral may not always improve fertility.

Supplementation with this mineral has been found both to improve sperm quality and to impair sperm quality, depending on the dosage and form of the supplement used.

In one study, eleven male participants were fed either a diet rich in natural selenium food sources or a diet with low selenium content for 120 days. At the end of the treatment period, participants on the high-selenium diet had lower sperm motility by 18%.

According to the researchers, “Serum triiodothyronine decreased and thyroid-stimulating hormone increased in the high-selenium group, suggesting that altered thyroid hormone metabolism may have affected sperm motility.” [6]

Additional Benefits and Uses

According to Dr. Joseph Mercola, because selenium is a potent antioxidant, it may support health and improve risk factors for various chronic diseases.

He says that getting adequate intake of this mineral along with other nutrients like vitamin E can help cells to resist and repair damage from oxidative stress.

Research shows that selenium may also have benefits for the following:

• Type 2 diabetes mellitus;
• Cardiovascular disease;
• Viral diseases;
• Poor memory;
• Asthma;
• Arthritis; [5]

However, selenium has not been approved by the FDA as a drug for the prevention or treatment of any of these conditions. More research is needed to evaluate therapeutic efficacy.

In one study, a combination of Vitamin C, Vitamin E, beta-carotene (pro-Vitamin A) and selenium was shown to diminish oxidative damage to lipids and influence serum cholesterol levels. However, this study did not find a protective effect against the progression of cardiovascular disease.

Dr. Mercola also points out the importance of selenium for detoxifying heavy metals, supporting blood sugar regulation, insulin sensitivity and the immune system’s responses to infection.

Selenium is found in 25-30 different selenoproteins that have various functions in the human body. This includes glutathione peroxidases (GPx1-GPx6) which are involved in detoxification pathways in the body.

Selenium Supplement Side Effects

Selenium deficiencies are rare in most countries. It is much more likely to develop selenium toxicity from over-use of dietary supplements containing this mineral.

The upper tolerable level (UL) for selenium is 400 mcg per day. Consuming more than this amount may increase your risk of side effects.

The Mayo Clinic reports the following symptoms of getting too much selenium in the diet:

• Breath and/or sweat that smells like garlic;
• Unusual weakness in muscles;
• Gas, bloating and/or diarrhea;
• Feeling tired all the time;
• Weak, brittle fingernails;
• Nausea and/or vomiting;
• Itchy skin;
• Irritability;
• Hair loss;

If you believe you might be getting too much selenium, or too little, then it is best to have your doctor run appropriate tests to determine your trace mineral levels. Imbalances in vital nutrients can cause very serious health problems.

Taking selenium with a multi-vitamin can also cause interactions with prescription medications. According to Drugs.com, selenium is known to interact with at least 28 different drugs with 71 combined brand and generic names.

Seek medical advice before beginning to use a selenium vitamin supplement or increasing your intake of food sources of this micromineral.

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