Foods High In Selenium: Antioxidant Mineral and Food Sources

Selenium is an essential trace mineral your body needs. This powerful antioxidant plays a vital role in your overall health. As an essential nutrient, selenium intake is crucial. While global selenium deficiency is not common, certain regions, like parts of China and Europe, experience low levels. Projections suggest climate change may even increase worldwide deficiency. Understanding Foods High In Selenium is key to maintaining your health and preventing various issues.

Key Takeaways

Selenium is an important mineral. It helps protect your body’s cells from damage.
Selenium keeps your thyroid healthy. It also makes your immune system stronger.
You can get selenium from many foods. Good sources include Brazil nuts, seafood, and whole grains.
Eat the right amount of selenium. Too little or too much can cause health problems.

What Is Selenium

Selenium is an essential trace mineral. Your body needs it in small amounts to function correctly. Think of it as a vital helper for many processes inside you. This mineral does not work alone. It is a key part of special proteins called selenoproteins. These proteins carry out many important jobs.

Selenium’s Role in the Body

Selenium plays a fundamental role in your body’s health. It helps with your metabolism. Your body takes in selenium, processes it, and then uses it. For example, your red blood cells take in selenite. They change it into selenide. This selenide then travels to your liver. In your liver, selenium helps form important compounds. These compounds are then used or removed from your body. Some microorganisms even use selenium in enzymes like formate dehydrogenase. This enzyme helps change formate into carbon dioxide. Another enzyme, thioredoxin reductase, uses selenium to reduce disulfide bonds. This shows how selenium is crucial for many biological reactions.

Antioxidant Power of Selenium

Selenium is a powerful antioxidant. It helps protects against oxidative stress. Oxidative stress happens when there are too many harmful molecules called free radicals in your body. These free radicals can damage your cells. Selenium helps fight this damage. It does this in several ways.

First, selenium compounds directly remove these harmful molecules. They act like tiny clean-up crews. Second, selenium can bind to metal ions. These metal ions, like iron and copper, can create more harmful radicals. By binding to them, selenium stops this process. Third, selenium helps break down hydrogen peroxide. This is a harmful substance that can damage cells.

Many important antioxidant enzymes need selenium to work. These include glutathione peroxidases (GPX1–GPX4 and GPX6) and thioredoxin reductases (TXNRD1–2). GPX4 is especially good at stopping fat damage in your cells. Selenoprotein P also helps protect your blood vessel linings. All these enzymes rely on selenium to keep your cells healthy and safe from damage.

Health Benefits of Selenium

Selenium offers many important benefits for your body. It helps keep you healthy in several ways. Understanding these health benefits of selenium shows you why this trace mineral is so vital.

Thyroid Health Support

Your thyroid gland needs selenium to work correctly. This gland makes hormones that control your body’s energy. Selenium helps your thyroid produce these hormones. It also protects your thyroid from damage.

A study looked at many U.S. adults. It found that more selenium intake was linked to lower levels of a thyroid hormone called TT4. It also affected the ratio of TT4 to another hormone, TT3. This link was stronger in men and people with enough iodine. Selenium’s anti-inflammatory and antioxidant roles are key here. Selenoproteins improve thyroid function. They help regulate hormone making and release. They also clean up harmful hydrogen peroxide. This hydrogen peroxide can damage your thyroid.

Another study showed that too much or too little selenium affects your thyroid hormones. High selenium intake led to lower T3 levels and weight gain. Low selenium intake caused higher T3 levels and less body fat. This means both extremes can impact your thyroid.

Selenium is crucial for stopping hydrogen peroxide from building up. Your thyroid makes hydrogen peroxide when it converts hormones. If you do not have enough selenium, this harmful substance can build up. It causes damage and inflammation in your thyroid. This inflammation can start an immune response. It can lead to antibodies and autoimmune diseases like Hashimoto’s thyroiditis. So, a lack of selenium can increase your risk for Hashimoto’s.

Research shows that taking selenium supplements can help people with Hashimoto’s. It reduces levels of TPO antibodies. It also improves how your thyroid looks on ultrasound. People often feel better too. Studies show thyroid antibodies can drop by up to 40% in a few months with enough selenium. Animal studies suggest selenium can stop autoimmune thyroiditis caused by iodine. It also increases special T cells that help your immune system. These cells stop immune cells from attacking your thyroid. This shows how important selenium is for thyroid health.

Study (Year)	Key Finding
Krysiak & Okopien (2011)	Looked at how levothyroxine and selenomethionine affected immune cells in women with Hashimoto’s thyroiditis.
Nacamulli et al. (2010)	Studied how normal selenium intake affected autoimmune thyroiditis over time.
Karanikas et al. (2008)	Found no immune benefits from selenium in patients with autoimmune thyroiditis.
Mazokopakis et al. (2007)	Reported on the effects of 12 months of L-selenomethionine on TPO antibody levels in Hashimoto’s patients.
Gartner et al. (2002)	Showed selenium supplements lowered thyroid peroxidase antibodies in autoimmune thyroiditis patients.
Deng et al. (2013)	Studied selenium’s effect on Hashimoto thyroiditis when thyroid function was normal.
Zhu et al. (2013)	Investigated selenium’s effects on autoimmune antibodies in diffuse toxic goiter.
Zhang et al. (2013)	Examined selenium’s effect on thyroid peroxidase and thyroglobulin antibodies in Hashimoto thyroiditis.
Yan et al. (2008)	Studied selenium’s effect on Hashimoto thyroiditis.
Pirola et al. (2016)	Suggested selenium could restore normal thyroid function in subclinical hypothyroid patients with autoimmune thyroiditis.
Kachouei et al. (2018)	Compared levothyroxine with selenium versus levothyroxine alone for reducing anti-thyroid peroxidase antibody levels.
Karimi & Omrani (2019)	Investigated selenium and vitamin C effects on anti-thyroid peroxidase antibody levels in autoimmune thyroiditis patients.

Immune System Boost

Selenium aids the immune system by making it stronger. It helps your body fight off sickness. Selenium helps both parts of your immune system: the one that attacks invaders directly and the one that makes antibodies.

Selenium helps specific immune cells work better.

It increases the ability of Cytotoxic T Lymphocytes (CTL) to kill tumor cells.
It boosts the growth of lymphocytes when they are stimulated.
It improves the growth of lymphocytes in mixed reactions.
It significantly increases how T-lymphocytes respond to signals.
It improves how polymorphonuclear leukocytes (PMN) move and engulf invaders, especially in older patients.
It increases phagocytosis, which is when immune cells “eat” harmful particles.
It enhances lymphoproliferation, the rapid growth of lymphocytes.
It boosts NK cell activity, which helps kill infected cells.
It raises IL-2 release, a signal for immune cells.
It increases the number of T cells, especially CD4+ T cells.
It enhances NK cell-mediated killing after three months of supplementation.

Selenoproteins are very important for T-cells. T-cells are easily damaged by oxidative stress. If you do not have enough selenoproteins, T-cells do not grow as well. Studies show that selenium supplements can improve lymphocyte growth. This is linked to better expression of the IL-2 receptor. High selenium in mice led to more IL-2 and its receptor. It also increased T-cell signaling and CD4+ T-cell functions. This shift helps your body fight viruses better.

Research on chickens with avian influenza showed that selenium supplements greatly reduced the virus. Chickens given high doses of selenium-enriched yeast had much less virus in their samples. They also shed less virus. This means dietary selenium can boost antiviral immunity. It lowers the amount of virus in the body.

Selenium’s immune-boosting benefits come from its antioxidant role. It helps regulate glutathione peroxidase (GPx). GPx is an enzyme that neutralizes harmful reactive oxygen species (ROS). This reduces oxidative stress and protects immune cells. Selenium also influences T helper responses. It helps control inflammation. This is important for clearing infections and preventing too much damage. Studies show that a lack of selenium can make infections worse. For example, mice with influenza had more lung damage when they lacked selenium.

Keeping enough selenium in your diet protects you from many viral infections. Selenium supplements can strengthen your body’s natural antiviral responses. For example, it reduces the severity of avian influenza. If you have a selenium deficiency, supplements can greatly improve your immune response to viruses. This is especially true for viral infections like COVID-19. Micronutrients play a big role in how your immune system works. Deficiencies can make you more likely to get severe illness.

Cellular Protection

Selenium protects your cells from damage. It does this mainly through special proteins called selenoproteins. These proteins are powerful antioxidants. They shield your cells from oxidative stress.

Selenium, when part of seleno-enzymes, is vital for proper thyroid health. It protects cells from oxidative damage. This damage comes from hydrogen peroxide during thyroid hormone making.
Selenocompounds increase GPx activity. This shows that selenoproteins provide these protective benefits.

Selenoproteins are key to selenium’s antioxidant effects. They contain selenocysteine.

These selenoproteins act as strong antioxidants. They protect cells from oxidative stress.
Glutathione peroxidase (GPx) is a well-known selenoprotein. It neutralizes hydrogen peroxide and lipid peroxides. This stops cell damage. Selenium is essential for GPx to work well.
Thioredoxin reductases are another group of selenoproteins. They also contain selenium. They help keep your cells balanced. They reduce the harmful effects of Reactive Oxygen Species (ROS).

Selenium also works with other enzymes.

It acts as a helper for enzymes like catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH PX). These enzymes remove free radicals and other harmful substances from cells. This protects them from oxidative stress.
Nano selenium can directly remove Reactive Oxygen Species (ROS). For example, special nano selenium particles can effectively clean up free radicals. They reduce ROS in skin and intestinal cells. This effect gets stronger with more selenium.

Studies on cells show that a lack of selenium reduces the activity of selenium-dependent enzymes. These include glutathione peroxidases and thioredoxin reductase. It also lowers cell survival. This deficiency led to more cellular reactive oxygen species (ROS). Especially, it increased lipid hydroperoxides. These caused cell death. Sodium selenite and alpha-tocopherol stopped this ROS increase. This suggests selenium and vitamin E work together. They defend against oxidative stress. They do this by detoxifying and stopping lipid hydroperoxides from forming.

Selenium’s protective benefits come mainly from selenoproteins.

Glutathione peroxidases (GPXs) and thioredoxin reductase are crucial antioxidants.
GPXs, like GPX1 and GPX4, remove reactive oxygen species (ROS). They balance cell chemistry. They reduce cell damage, including damage to fats.
Selenium and selenoproteins help repair DNA. They prevent DNA damage. They also boost the activity of repair enzymes. These include DNA glycosylase, p53, BRCA1, and Gadd45.
Selenium and selenoproteins stop cell death. Strong triggers like radiation often cause cell death. Selenium helps prevent this by reducing DNA damage and ROS overload.

Reproductive Health

Selenium plays a crucial role in reproductive health for both men and women.

For men, selenium is vital for fertility.

Selenium acts as an antioxidant. It protects sperm cells from oxidative damage. Free radicals cause this damage during sperm development.
It helps keep sperm cells healthy. This is very important for successful reproduction.
A lack of selenium is linked to poor sperm quality. It affects how sperm look and how well they move.
Enough selenium is essential for keeping sperm cell membranes intact.
Selenium helps make selenoproteins. These are important for sperm movement and function. They improve how sperm swim.
Studies show that selenium supplements improve how sperm move forward. They can also increase the percentage of moving sperm.
Selenium is part of selenoproteins like glutathione peroxidase. These protect sperm from oxidative damage. They neutralize harmful free radicals and protect sperm DNA.
It helps keep the sperm tail strong. This is essential for sperm to move.
A lack of selenium can lead to abnormal sperm and poor movement. Both contribute to male infertility.
Taking selenium supplements has greatly improved sperm movement and shape in men with low selenium and poor sperm quality.
Selenium is a core part of your body’s antioxidant defense. GPX, which contains selenium, is crucial for making sperm, maturing them, and helping them move.
It helps regulate male reproduction. This is because of its strong antioxidant and anti-inflammatory properties.
Selenium levels in semen are strongly linked to semen quality.
Proper selenium supplements can improve semen quality in infertile men.
A lack of selenium is linked to less high-quality sperm. It also links to problems with sperm maturation and male infertility.

For women, selenium balance is also important for reproductive health.

Too little or too much selenium can lead to infertility. This shows up as poorly developed ovaries.
Implantation failure can happen. This is due to poor embryo development and changes in the uterus.
Both too little and too much selenium are linked to lower libido.
Selenium imbalance is connected to pregnancy problems. These include miscarriage, pre-eclampsia, gestational diabetes, slow fetal growth, and early birth.
In reproductive tissues, selenium is part of selenoproteins/selenoenzymes. These are in antioxidant systems like glutathione peroxidases (GPX), iodothyronine deiodinases (DIO), and thioredoxin reductases (TXNR). They reduce reactive oxygen species and minimize DNA damage.
Low selenium levels in blood, follicular fluid, amniotic fluid, or tissues are linked to unexplained infertility. They also link to miscarriage, early birth, gestational diabetes, and small babies.
An autoantibody called elevated Se-binding protein 1 is found in women with unexplained infertility and early ovarian failure.
Women with gestational diabetes often have low serum selenium levels. Supplements have improved blood sugar and fat levels in these women.

Potential Cancer Protection

Selenium may help protect you from certain cancers. Research suggests a link between selenium intake and a lower risk of cancer.

A study in Vietnam looked at many cancer cases and healthy people. It found a U-shaped link between dietary selenium intake and cancer risk. This means both very low and very high selenium levels increased cancer risk. For example, people with the lowest intake had a much higher risk. Those with the highest intake also had a higher risk. This was compared to a “safe intake” range. This U-shaped pattern appeared for stomach, colon, rectum, and lung cancers.

These findings match other studies. A study in Poland also found a U-shaped link between blood selenium levels and cancer risk. It showed that people with very low or very high blood selenium levels had an increased risk of cancer. This was compared to those with moderate levels.

Selenium Intake and Food Sources

Foods High In Selenium

Many delicious foods contain selenium. You can easily meet your daily selenium needs by including these foods in your diet. Here are some of the top foods high in selenium:

Meat and Poultry:
- Cooked Skirt Steak: A 6-ounce steak gives you 61.2 mcg (111% of your daily value).
- Lean Chicken Breast: A 6-ounce breast provides 54.2 mcg (99% of your daily value).
- Turkey: This is another excellent source.
- Organ meats like liver also offer significant selenium.
Seafood: Many types of fish and shellfish are foods high in selenium.
- Shrimp: About 12 large shrimp (3 ounces) contain 42.1 mcg (77% of your daily value).
- Yellowfin tuna: This fish is a great choice for selenium.
- Other fish and shellfish are also good sources.
Plant-Based Options: You have many plant-based foods high in selenium too.
- Brazil nuts: These are exceptionally high in selenium. A single Brazil nut can contain 96 mcg of selenium. However, the selenium content in Brazil nuts can vary greatly, from 0.03 to 512 mcg per gram. This means you should eat Brazil nuts in moderation to avoid getting too much selenium.
- Firm Tofu: One cup provides 43.8 mcg (80% of your daily value).
- Whole Wheat Pasta: One cup offers 42.5 mcg (77% of your daily value).
- Shiitake Mushrooms: One cup cooked gives you 36 mcg (65% of your daily value).
- Other plant-based sources include:
  - Cruciferous vegetables (like broccoli and white cabbage)
  - Bulb vegetables (such as garlic and onion)
  - Asparagus
  - Pulses (like lentils and beans)
  - Sunflower seeds
  - Chia seeds
  - Barley
  - Whole wheat bread
  - Baked beans: One cup of canned baked beans provides about 13 mcg.
  - Oatmeal
  - Flax seeds
  - Chickpeas
  - Quinoa

Here is a list of some plant-based foods that contain selenium:

Brazil nuts: 68-91 mcg per nut
Pasta (enriched or unenriched, 1 cup): 30 mcg
Brown rice (1 cup cooked): 19 mcg
Cremini mushrooms (1 cup): 18.7 mcg
Sunflower seeds (¼ cup): 18.5 mcg
Portabella mushrooms (1 cup): 16 mcg
Chia seeds (1 oz): 15.6 mcg
Firm tofu (⅕ block): 14 mcg
Barley (1 cup cooked): 13.5 mcg
Whole wheat bread (1 slice): 13 mcg
Baked beans, canned (1 cup): 13 mcg
Oatmeal (1 cup): 13 mcg
Flax seeds (¼ cup whole): 11 mcg
Sunflower seed kernels (1 oz): 10 mcg
White mushrooms (1 cup): 6.5 mcg
Chickpeas (1 cup): 6 mcg
Lentils (1 cup): 6 mcg
White bread (1 slice): 6 mcg
Grits (1 cup): 6 mcg
Quinoa (1 cup cooked): 5 mcg

Good Sources of Selenium

The selenium content of foods can vary. This often depends on where the food comes from. For example, the soil’s selenium content greatly affects how much selenium plants absorb. This means the same type of food might have different selenium levels depending on its growing region.

The amount of selenium in crops is mainly affected by the soil. However, other factors also play a role. These include the specific plant species and its ability to absorb and store selenium. For instance, soil selenium levels in some areas can range from 0.09 to 4.60 mg/kg. Yet, the average selenium content in crops grown there varies significantly. Wheat might have 0.084 mg/kg, while jujubes only have 0.039 mg/kg. This shows that different crops take up selenium at different rates, even in the same soil.

Irrigation practices can also increase selenium in the soil and crops. Farmland with intense irrigation often has higher selenium in the soil around plant roots and in the crops themselves. This is compared to fields that rely only on rain. However, for some crops, their natural ability to absorb selenium is more important than just the soil’s selenium levels.

To ensure you get enough selenium, focus on a varied diet. Include a mix of these excellent sources. This helps you cover your bases and get all the selenium you need. Remember to include a variety of nuts, beans, fish, and whole grains in your meals.

Selenium Deficiency and Toxicity

You need the right amount of selenium for good health. Both too little and too much selenium can cause problems.

Signs of Deficiency

When you do not get enough selenium, you can experience a selenium deficiency. This deficiency can show up in many ways. You might notice thin, dull hair or even hair loss. White spots can appear on your nails. Your skin might look pale and feel dry. You could also feel tired, have muscle weakness, or experience joint pain. Your immune system might weaken, making you more likely to get sick.

A more serious selenium deficiency can lead to bigger problems. You might have thyroid disorders, which can cause weight changes. Men can face fertility problems. Women might see poorer cognitive development in their children during pregnancy. If you experience these symptoms, a selenium test can measure the selenium level in your blood. This helps you know if your selenium levels are healthy. Other tests, like a Selenium Red Blood Cell (RBC) Test, give a long-term view of your selenium status.

Risks of Excess Selenium

Getting too much selenium also carries risks. This is called selenium toxicity. Symptoms of selenium toxicity can include a garlic odor on your breath, hair loss, and brittle nails. You might also experience nausea, diarrhea, and fatigue. Some people report memory loss, mood swings, and irritability. In severe cases, acute toxicity can lead to heart problems, neurological symptoms like tremors, and even pulmonary edema. Chronic selenium toxicity, or selenosis, can cause nerve damage and skin lesions. The risks of excess selenium are serious.

Supplementation Considerations

You should be careful with selenium supplements. The tolerable upper intake level (UL) for adults is 255 micrograms per day. Medical professionals advise you not to consume more than 400 micrograms of selenium daily. Exceeding this amount increases your risks of toxicity. Doses over 300 micrograms per day have even been linked to increased mortality.

Taking selenium supplements without medical supervision can lead to nausea, fatigue, and changes in liver or kidney function. Many supplements use organic selenium, like selenomethionine, or inorganic forms such as sodium selenite. Always talk to a healthcare professional before starting any selenium supplement. They can help you understand your needs and avoid the risks of too much selenium.

You now know selenium is a vital mineral. It acts as a powerful antioxidant. It protects your cells and supports your thyroid and immune system. You get selenium from many foods. Eat a balanced diet rich in Brazil nuts, seafood, and whole grains. Always talk to a healthcare professional. They can give you personalized advice on selenium intake or supplements.

FAQ

What is selenium’s main job in your body?

Selenium acts as a powerful antioxidant. It protects your cells from damage caused by harmful molecules called free radicals. This helps keep your body healthy and supports many vital functions, like thyroid health and your immune system.

What foods give you the most selenium?

Brazil nuts are exceptionally high in selenium. Seafood like shrimp and tuna also provide a lot. You can also find selenium in lean meats, poultry, eggs, whole grains, and some vegetables like shiitake mushrooms and garlic.

What happens if you do not get enough selenium?

If you lack selenium, you might experience hair loss, brittle nails, or dry skin. Your immune system can weaken, making you more prone to illness. It can also affect your thyroid function and reproductive health.

What happens if you get too much selenium?

Too much selenium can cause toxicity. You might notice a garlic smell on your breath, hair loss, and brittle nails. Other symptoms include nausea, diarrhea, and fatigue. Always follow recommended intake levels to avoid these issues.