Selenium (selenomethionine) is a mineral necessary for the healthy functioning of the body, including the immune system and your metabolism, regulating the thyroid and promoting testosterone levels. Eating a variety of foods can help you meet the required daily amounts. Selenium's benefits are far-reaching, so how do you make sure you get enough, and what does it do?
Selenium is a trace mineral and a critical component of various proteins and enzymes called selenoproteins. They are involved in DNA production and help protect against cell damage and infection.(1)
It plays a crucial role in how selenium regulates thyroid and testosterone levels in men. It's vital for various physiological functions in the human body, including regulating thyroid and testosterone levels. (2) Here's how selenium is involved in these processes:
Thyroid Function
Thyroid protection: The thyroid gland produces hormones responsible for regulating metabolism, growth, and development. Selenium is a critical component of several enzymes involved in the metabolism of thyroid hormones.
Antioxidant protection: The thyroid gland is highly susceptible to oxidative stress due to its high metabolic activity and the generation of reactive oxygen species (ROS). Selenium is an essential component of antioxidant enzymes, such as glutathione peroxidase, which helps protect the thyroid gland from oxidative damage.
Thyroid hormone conversion: Thyroxine (T4) is the inactive form of thyroid hormone, and only by converting it into the active form, triiodothyronine (T3), in peripheral tissues does it become bioavailable. Selenium is involved in the conversion process by influencing the activity of deiodinase enzymes, which convert T4 to T3. T3 is the more biologically active form of thyroid hormone that controls the body's metabolic rate and energy production.
Thyroid hormone regulation: Selenium also plays a role in regulating thyroid hormone levels. It helps maintain the balance between the production and metabolism of thyroid hormones, preventing overproduction (hyperthyroidism) and underproduction (hypothyroidism) of thyroid hormones.
How a Selenium Deficiency Affects Thyroid
Since selenium is vital to thyroid health, having enough is crucial for preventing thyroid disease. (3) While most people get enough selenium through diet, those who don't can be at risk for several thyroid-related issues that include:
- Impaired hormone production: Selenium deficiency can hinder the synthesis of thyroid hormones, leading to decreased levels of T4 and T3. This can contribute to hypothyroidism, characterized by symptoms such as fatigue, weight gain, and cold intolerance.
- Increased autoimmune thyroid disorders: Selenium deficiency is associated with an increased risk of autoimmune thyroid disorders, including Hashimoto's thyroiditis and Graves' disease. Adequate selenium levels may help modulate the immune response and reduce the risk of autoimmune thyroid conditions.
It's important to note that while selenium is essential for thyroid function, excessive intake can also have adverse effects. (4) High levels of selenium can lead to nausea, vomiting, hair loss, irritability, foul breath, nail discoloration and fatigue.
Therefore, maintaining a balanced selenium intake is crucial for optimal thyroid function. The recommended dietary allowance (RDA) for selenium is around 55 micrograms per day for adults. (5) However, specific selenium requirements may vary based on age, sex, and overall health.
Selenium May Benefit Testosterone Production
Testosterone is the primary male sex hormone, although females produce it in smaller amounts. In men, it plays a vital role in the development of the reproductive system, as well as the secondary sex characteristics such as muscle growth, bone mass, body and facial hair and a deepening of the voice.
Selenium benefits testosterone synthesis in two ways:
1. Testicular Function
Selenium is required for the normal development and function of the testes. It helps maintain testicular tissue and supports the production of healthy sperm. Selenium deficiency has been associated with impaired testicular function and reduced testosterone levels.
2. Antioxidant Protection
Like its role in the thyroid gland, selenium acts as an antioxidant in the testes, protecting them from oxidative stress. This antioxidant activity helps maintain the health and function of Leydig cells, which are responsible for testosterone production.
Selenium May Benefit Fertility
Studies (6) have suggested that selenium supplementation can improve sperm quality and fertility in men with infertility issues and may benefit individuals with suboptimal testosterone levels, potentially enhancing libido, muscle mass, and overall vitality. However, more research is needed to establish optimal dosages and long-term effects.
Selenium-Rich Foods to Include in Your Diet
According to studies (7), the recommended daily intake of selenium for adults is around 55 micrograms per day. Although it can be taken in supplement form, consuming selenium-rich foods can help meet the body's requirements in most cases.
Some foods rich in selenium Include:
- Brazil nuts: Brazil nuts are one of the richest sources of selenium. Just a few nuts can provide your daily selenium requirements. However, be cautious not to consume them excessively, as high selenium intake can have adverse effects.
- Seafood: Fish and shellfish are excellent sources of selenium. Tuna, salmon, sardines, shrimp, and crab are excellent choices. The selenium content can vary depending on the fish and its origin.
- Poultry: Chicken and turkey are good sources of selenium. The selenium content is higher in the meat and darker parts, such as the thighs and drumsticks.
- Eggs: Eggs, especially the yolks, contain selenium. Opt for free-range or organic eggs when possible, as they tend to have higher nutrient levels.
- Whole grains: Whole grains like brown rice, quinoa, oats, and wheat germ contain selenium. However, the exact amount can vary depending on the soil conditions in which they were grown.
- Legumes: Legumes such as lentils, chickpeas, and beans provide moderate amounts of selenium and other essential nutrients.
- Mushrooms: Some varieties of mushrooms, including shiitake, button, and crimini mushrooms, are known to contain selenium. The selenium content in mushrooms can vary based on the soil they are grown in.
- Seeds: Sesame seeds and sunflower seeds are good sources of selenium. Including them in your diet can contribute to your selenium intake.
It's worth noting that the selenium content of the soil can change the amount of selenium in the foods so that the levels may vary wildly across food sources. However, incorporating a varied diet with these selenium-rich foods can help ensure you meet your body's selenium needs.
Are there Benefits to Selenium Supplements
While it's pretty easy to get enough selenium through diet, some health concerns can make it more difficult (8), such as:
- People living with HIV: HIV can slow mineral absorption and cause diarrhea and lack of appetite, possibly causing mineral deficiencies.
- People who require kidney dialysis: The process of filtering blood can remove some selenium. Also, dietary restrictions required with kidney failure may decrease food intake, leading to a risk of selenium deficiency.
- People who eat foods low in selenium: The virus can lead to diarrhea, malabsorption of nutrients, and decreased appetite.
- People who live in areas where the soil lacks selenium: This is rare within the United States; however, some regions of China, Russia, and Europe have selenium-deficient soils, which pose a potential risk to some people. The risk escalates for individuals residing in these regions following vegetarian or vegan dietary patterns.
In some cases, taking a selenium supplement may be a good idea to ensure you get the proper amount for optimal health. The benefit of selenium supplementation may also help improve thyroid and testosterone production.
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Conclusion: The Benefits of Selenium
Selenium benefits overall health and the proper functioning of the body. It protects the body from oxidative stress, boosts the immune system, benefits the heart, and promotes hormone health, thyroid function and testosterone production. Supplementation shouldn't be necessary if you have enough selenium in your diet. However, selenium may benefit testosterone and thyroid hormone production in men.
