Selenium is a non-metallic trace element that is essential for both human and animal life. It is found in the soil, water, and certain foods.

Selenium is an important antioxidant that helps protect cells from damage caused by free radicals and oxidative stress.

Where is Selenium Found?

Selenium is found in soil, rocks, and water. It is most commonly found in areas with high levels of granite or limestone in the soil. In the United States, the Great Plains and the Pacific Northwest are known to have high levels of selenium in the soil.

The concentration of selenium in soil varies greatly depending on the location, climate, and natural sources.

Additionally, selenium can be found in certain foods, including:.

Nuts and seeds
Seafood
Organ meats
Whole grains
Dairy products

It is important to note that the concentration of selenium in these foods also varies widely depending on the location and farming practices.

Some areas of the world are known to have low levels of selenium in the soil, which can lead to selenium deficiency in humans and animals.

What Does Selenium Do?

Selenium is an important nutrient that has many functions in the human body. Here are some of the key roles of selenium:.

1. Antioxidant

Selenium helps protect cells from damage caused by free radicals. Free radicals are unstable molecules that can cause damage to cells and contribute to aging and disease.

By neutralizing free radicals, selenium can help protect cells from damage and reduce the risk of chronic diseases.

2. Immune System Support

Selenium plays an important role in the functioning of the immune system. It helps prevent oxidative damage to immune cells, which can impair immune function.

Additionally, selenium is involved in the production of cytokines, which are important for immune function.

3. Thyroid Function

Selenium is essential for the production of thyroid hormones. The thyroid gland requires selenium to convert the inactive form of thyroid hormone (T4) to the active form (T3).

Without selenium, the thyroid gland cannot produce enough thyroid hormone, which can lead to hypothyroidism.

4. Reproductive Health

Selenium is important for both male and female reproductive health. In men, selenium is important for the production of sperm. In women, selenium levels are known to decline during pregnancy, which can lead to adverse outcomes.

Some studies have suggested that selenium supplementation during pregnancy may reduce the risk of preterm birth and other complications.

5. Cancer Prevention

Some studies have suggested that selenium may help reduce the risk of certain types of cancer. Selenium has been shown to have anti-cancer properties and may help prevent tumor growth.

However, more research is needed to fully understand the role of selenium in cancer prevention.

Selenium Deficiency

Selenium deficiency is rare in the United States, but it can occur in certain populations.

People who live in areas with low levels of selenium in the soil, as well as those with digestive disorders that impair selenium absorption, may be at risk for selenium deficiency. Symptoms of selenium deficiency include:.

Weakness and fatigue
Muscle pain and tenderness
Joint pain and stiffness
Slow wound healing
Infertility
Thyroid problems

Selenium deficiency can also have serious consequences for animal health. Agricultural animals such as cows, sheep, and horses can develop a condition known as white muscle disease, which is caused by selenium deficiency.

Selenium Toxicity

While selenium is essential for health, too much selenium can be toxic. The upper limit for selenium intake is 400 micrograms per day for adults. Consuming more than this amount can lead to selenium toxicity, which can cause symptoms such as:.

Nausea and vomiting
Diarrhea
Circulatory collapse
Respiratory failure
Blurred vision or blindness

Selenium toxicity is most commonly associated with high levels of selenium in the soil and water. In some areas, natural sources of selenium can result in high levels of selenium in certain foods.

It is important to be aware of the selenium content in your food and water to avoid selenium toxicity.

Conclusion

Selenium is an important nutrient that is essential for human and animal health.

It is found in soil, water, and certain foods, and plays a key role in antioxidant function, immune system support, thyroid function, reproductive health, and cancer prevention. While selenium deficiency is rare in the United States, too much selenium can be toxic, so it is important to be mindful of your selenium intake.