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What is Selenium?

What is Selenium?

What is Selenium?

Selenium is a micronutrient that occurs naturally (a mineral) in many foods and is also available as a food supplement. Selenium, which is vital for humans, plays a crucial role in metabolism, DNA synthesis, protection against infection, strengthening the immune system, and preventing damage caused by free radicals. Selenium deficiency can cause a number of health problems.

What are the symptoms of selenium deficiency?

Selenium deficiency can cause a number of symptoms. The most common cases are the following:

  1. Weakness of the immune system;

  2. Infertility in men and women;

  3. Muscle weakness;

  4. Fatigue or weakness;

  5. Confusion of thoughts;

  6. Hair loss and etc.

What is the recommended daily intake of selenium?

The World Health Organization has defined the maximum daily intake as follows::






During lactation

0-6 month

45 mg

45 mg



7–12 month

60 mg

60 mg



1–3 years old

90 mg

90 mg



4–8 years old

150 mg

150 mg



9–13 years old

280 mg

280 mg



14–18 years old

400 mg

400 mg

400 mg

400 mg

19 years old and above 

400 mg

400 mg

400 mg

400 mg

7 benefits of selenium

  1. It acts as a strong antioxidant.

Free radicals are byproducts of various metabolic processes in the body, and their accumulation in large amounts is dangerous because they can cause oxidative stress and cause DNA mutations, leading to cancer, cardiovascular disease, immune dysfunction, and neurological disease.

Selenium is a powerful antioxidant that fights oxidative stress and helps protect your body from many chronic diseases. Antioxidants are compounds in foods that prevent cell damage caused by free radicals. Alcohol and tobacco use, stress and other factors cause an increase in free radicals, which leads to oxidative stress that damages healthy cells. Oxidative stress leads to problems such as heart disease, Alzheimer's, cancer, premature aging.

       2. Cancer prevention (prophylactic measure)

Selenium is especially helpful if you have a weak immune system or a family history of cancer. According to studies, interventions with high-dose selenium treatment resulted in a 31% lower risk of cancer, a 45% lower risk of cancer death, and a 22% lower risk of prostate cancer in men. Other studies show that regions with lower levels of selenium have a higher risk of cancer than regions with higher levels. However, it should be noted that all these are the result of proper nutrition, not selenium-containing drugs.

On the other hand, based on a patient's individual genetics and cancer subtype, selenium can potentially inhibit chemotherapeutics and cause tumor growth.

        3. Prevention against cardiovascular disease

Previous studies have shown that individuals with low selenium status have a higher risk of cardiovascular disease. Experts suggest that selenium may reduce the risk of cardiovascular disease or death related to cardiovascular disease. Epidemiological data on the role of selenium in the development of cardiovascular diseases are based on the fact that a diet containing adequate amounts of selenium can reduce this risk.

        4. May help reduce asthma symptoms

Studies show that people with chronic asthma have lower levels of selenium. Also, asthma patients who take selenium-containing foods and supplements experience fewer symptoms than other patients.

       5. Extends life

Research shows how important selenium is for health and longevity. Selenium should play a major role in your diet if you want to live a long and healthy life.

Selenium plays an important role in the prevention of various diseases, from asthma to cancer. As we age, the risk of contracting many diseases increases, so it is an important factor to always take foods containing selenium and maintain it in the norm. Selenium is a mineral, which means it is needed in small amounts. However, because it plays a role in so many important functions in our body, it can get out of our system quite quickly, so you need to take it regularly to get the full benefits of selenium.

       6. Prevention against neurological diseases

Alzheimer's disease is a progressive neurological disease that results in brain malfunction and memory loss over time. Some studies show that people with this disease have low levels of selenium in their blood. In addition, selenium in both food and nutritional supplements can prevent the progression of the problem and improve memory in patients with Alzheimer's disease.

A study shows that taking one Brazil nut a day improves speech fluency and other mental functions in patients with mild cognitive impairment. Also, the so-called "Mediterranean" diet, which consists of foods high in selenium, such as seafood and nuts, further reduces the risk of developing Alzheimer's disease.

        7. Helps regulate thyroid hormone

Thyroid hormone controls metabolism, sleep, temperature, weight, energy, and many other important daily body functions, and when it's not working properly, it can have serious consequences. Selenium plays a key role in regulating the production and amount of thyroid hormones. Selenium deficiency can cause problems such as thyroid inflammation, hyperthyroidism (lack of thyroid hormones) and hypothyroidism (excess of thyroid hormones). Selenium deficiency causes thyroid Hashimoto's disease. Research shows that daily intake of selenium-rich foods and supplements can improve mood and overall well-being in patients with Hashimoto's disease.

The danger of excessive intake of selenium

Although selenium is necessary for health, its excessive intake can be dangerous and lead to poisoning and even death.

Although selenium poisoning is rare, it is important to get the required amount of selenium per day and never exceed 400 mg per day. Brazil nuts contain a lot of selenium in the extract, and its excessive intake leads to poisoning. However, poisoning occurs mainly when selenium is taken from food supplements, not from a diet containing selenium.

Symptoms of selenium poisoning include:

  1. Hair loss;
  2. Dizziness;
  3. Nausea;
  4. Vomiting;
  5. Weight loss;
  6. Scattering;
  7. Muscle pains;
  8. In rare cases, serious intestinal and neurological symptoms, heart disease, kidney failure and death can result.

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