Selenium Antioxidant Effects, Benefits & How it Works [Research Review]

Selenium is a potent antioxidant that helps our cells resist damage caused by oxidative stress and free radical particles.

Antioxidants are important for well-being and can influence heart health, immune function, longevity as well as risk factors for many different diseases and conditions.

Selenium is an essential mineral that serves as a cofactor for the primary antioxidant enzyme in the human body, glutathione peroxidase. These enzymes promote detoxification of harmful chemicals and support the immune system.

Because it exhibits significant antioxidant activity, Selenium has been studied for its anti-cancer effects. It has been shown in vitro to influence gene expression, DNA repair and protection, and to inhibit cancer cell progression.

Combining selenium with other natural antioxidants such as vitamin C, vitamin E, and beta-carotene has been found to reduce oxidative damage to lipid molecules in the body. This may have benefits for cardiovascular health.

While selenium does play an important role in the body as a natural antioxidant, it is not yet clear what effect supplementing with this mineral has on protecting our cells from oxidative damage.

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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Selenium Antioxidant Effects

Selenium (Se) is a trace mineral element with Atomic Number 34. It is incorporated into various selenoproteins and selenoenzymes in the human body which have wide-ranging physiological roles.

This mineral affects thyroid function, aging, resistance to disease, detoxification, cardiovascular health and blood lipid levels, blood sugar regulation, and demonstrates chemopreventative effects. [1]

Not having enough selenium in your diet for long periods of time can increase the risk for cardiomyopathy, coronary artery disease, irritable bowel syndrome, cataracts, chronic catarrhal colitis (CCC), rheumatoid arthritis, problems with muscle function, cirrhosis and psychological dysfunction.

One of the most prominent roles for selenium in the body is to prevent damage caused by reactive oxygen species (ROS) and other free radical particles.

In animal studies, selenium has been shown to fight oxidative stress and improve immune system strength by regulating these highly reactive oxygen-based molecules. [5]

Antioxidants protect cells from radical agents which can damage cells and tissues. These free radicals are molecules with unpaired electrons that can include both oxidative compounds produced naturally in the body and those derived from toxins in the environment.

Some sources of pro-oxidants include accumulated waste from normal cellular metabolism, radiation exposure (such as x-rays) environmental pollutants (such as smoke and smog) and certain food additives.

ROS (reactive oxygen species) result as natural byproducts of aerobic metabolism. In animal studies, selenium has been shown to fight oxidative stress and improve immune system strength by regulating these highly reactive oxygen-based molecules. [5]

While some forms of oxidation are healthy and normal, overexposure to these free radical particles can overwhelm cells and tissues, resulting in signs of oxidative stress.

Your cells are constantly exposed to free radical damage which can accumulate over time. You can think of oxidative stress as the “wear and tear” your cells endures throughout life.

According to Dr. Edward Group III, over time excessive oxidative stress can lead to cardiovascular disease, vision problems, type II diabetes, neurodegenerative diseases and more. He says that antioxidants like selenium can help to counteract oxidative stress by neutralizing radical agents inside the body.

How do Antioxidants Work?

According to MedLine Plus, antioxidants can be manmade or natural. They are substances that may inhibit or slow down certain types of cellular damage.

They work by lending electrons to free radical particles with unpaired electrons, helping to quench their reactivity.

Individuals can increase antioxidant activity in the body by eating certain foods and supplements.

Many foods contain antioxidants, especially organic vegetables and fruits. Some commonly-known antioxidants include selenium, beta-carotene, lycopene, lutein and vitamins A, C and E. [2]

A number of other ingredients have been shown to exhibit antioxidant activity in vitro, but may not influence oxidative damage when taken orally as dietary supplements.

The best way to improve resistance to oxidative stress is to increase the body’s endogenous antioxidant enzyme levels. [2]

Of the previously mentioned supplements, only selenium forms the chemical base of selenoproteins and selenoenzymes that are critical for the biosynthesis of endogenous antioxidants like glutathione peroxidase.

Selenium Health Benefits and Functions

A 2016 journal article published by the German Institute for Human Nutrition states that selenium may help to regulate a broad spectrum of physiological activities in humans.

There are 25 genes in humans that encode selenoproteins. Some of the biological processes that these proteins play a role in include:

• Cellular response to oxidative stress;
• Cellular differentiation;
• Immune response;
• Redox signaling;
• Protein folding;

This mineral is also incorporated into plasma selenium transport protein, selenoprotein P, iodothyronine deiodinases and thioredoxin reductases. [3]

Individual cells experience oxidative damage on a regular basis without necessarily interfering with human health. Our immune system can identify these cells for repair or for apoptosis (normal cell death).

However, when multiple cells in a tissue or organ system experience on-going damage, the body may begin to experience dysfunction.

According to research from Centre for Public Health Sciences in Queensland, Australia, selenium protects and fortifies the structure of cells and helps to support cellular metabolism. [4]

Researchers believe it is important for resisting disease associated with aging.

Selenium supplements are often used in combination with vitamin E, another well-known antioxidant that appears to have synergistic benefits. [6]

How Much Selenium Should You Take?

The US RDA (recommended dietary allowance) for selenium is 55 micrograms (mcg) per day in healthy adults over the age of 14. Infants, young children and pregnant or nursing mothers have different dietary requirements.

Most people who live in Europe or North America are able to obtain 55 mcg/day of this mineral from the foods they eat. Selenium deficiency is rare in most countries and among people who eat a nutritious and varied diet.

However, some individuals may need to increase their intake of this antioxidants to address specific health needs. Research suggests that people who follow diet programs like the Jenny Craig program may need to supplement their diet to obtain adequate selenium intake.

Both dietary modifications and supplements can be used to increase intake. Some examples of selenium-rich foods include brazil nuts, certain fish, ham, beef, turkey breast, chicken breast, cottage cheese, long-grain brown rise, eggs, whole wheat bread, spinach and cashew nuts.

Dietary supplements are also available in a number of different forms. Supplements typically are sold in either 200 mcg or 100 mcg dosages.

Safety & Side Effects

Selenium deficiency is rare, but if you are deficient in this mineral you have an increase risk for developing secondary illnesses and diseases.

Low selenium is also associated with male infertility and a type of osteoporosis called Kashin-Beck disease. A deficiency in this mineral may also worsen an existing iodine deficiency and lead to impaired thyroid function.

As an antioxidant supplement, selenium is rated Likely Safe by the Natural Medicines Database when taken at appropriate oral dosages. However, using more than 400 mcg per day or taking it for long periods of time is rated Possibly Unsafe.

Getting too much selenium for an extended duration can cause a condition called selenosis to develop. Early signs of selenosis include garlic breath, metallic taste, brittle hair/nails, hair/nail loss, mottled (spotted teeth) and/or fatigue.

Other possible early symptoms of selenosis include nausea, vomiting, irritability, diarrhea, skin rashes and/or nervous systems abnormalities.

Excessive intake of selenium and/or other antioxidants is associated with certain health risks. You should seek medical advice about using selenium for its antioxidant benefits to determine whether this supplement is appropriate for you.

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