Selenium stands out as one of the most overlooked nutrients that boost longevity and overall health. This powerful micronutrient forms part of over 25 selenoproteins that are vital to our body’s functions. The benefits of this trace element go beyond basic nutrition. Selenium works as an antioxidant that boosts immune function, regulates thyroid health and shows promising anti-cancer properties.
This piece will get into what selenium does for the body, including seven significant benefits. We’ll learn how it works in our body, where to find it in food and ways to supplement. We’ll cover signs of deficiency, potential risks of excess intake and the latest research about selenium’s role in longevity and optimal health.
What does selenium do in the body?
Selenium does much more than just act as a trace element in our bodies. The human body has 25 distinct selenoproteins that make this mineral a vital part of maintaining good health through many connected pathways.
Overview of selenium function in the body
Selenoproteins contain selenocysteine, which scientists call the 21st amino acid in the genetic code. These proteins power selenium’s many functions throughout our body’s systems. The most important selenium-dependent enzymes include glutathione peroxidases (GSH-Px), thioredoxin reductases and selenoprotein P.
Selenium’s main job protects us against oxidative stress. Glutathione peroxidases help break down hydrogen peroxide and organic hydroperoxides. This neutralizes these harmful compounds before they damage our cells. This antioxidant activity helps prevent damage to cell membranes.
The thyroid gland needs selenium to work properly. It has the highest concentration of selenium in the body because several selenoproteins support thyroid function. Selenium-dependent enzymes called iodothyronine deiodinases help convert inactive thyroid hormone (T4) to its active form (T3). This shows why we need the right amount of selenium to keep our thyroid working well.
Our immune system also benefits from selenium. Research shows that higher blood selenium levels associate with better immune response. A lack of selenium hurts immune cell function and can slow down immune response. Selenium helps natural killer cells work better, boosts T-cell and macrophage activity and helps produce antibodies.
Why it’s considered an essential trace mineral
Selenium earns its “essential” status for two main reasons. Our bodies can’t make selenium on their own, so we must get it from food. Even a small selenium shortage can seriously affect many body systems.
We only need tiny amounts of selenium, which explains the “trace” label. Yet without it, problems quickly develop throughout the body. Low selenium levels cause tissue glutathione peroxidase activity to drop sharply, which leads to various health problems. A selenium shortage makes toxic byproducts more dangerous and damages cell membranes.
Our body’s selenium distribution shows how important this mineral is. Skeletal muscles hold 28% to 46% of the body’s total selenium, while other tissues maintain specific amounts they need. The body controls selenium levels by removing excess through urine and when intake is high, through the lungs and feces.
Scientists found that a lack of selenium can turn harmless viruses into dangerous pathogens. This shows how this tiny mineral helps maintain our body’s balance and strength against environmental stress.
How it works with other nutrients like vitamin E
Selenium and vitamin E work together in one of nutrition’s most interesting partnerships. Karl Schwarz made this discovery while studying liver problems in rats. He found both vitamin E and selenium (which he called “factor 3”) could prevent liver damage independently.
These nutrients team up as antioxidants in different ways. Vitamin E (α-tocopherol) tackles lipid hydroperoxyl radicals in cell membranes and turns them into lipid hydroperoxides. Then selenium-dependent glutathione peroxidase changes these into harmless lipid alcohols and water. This teamwork prevents cell membrane damage.
Nutritionists call selenium and vitamin E’s relationship “mutually sparing”. Having enough of one nutrient can help make up for a shortage of the other. The best protection against oxidative stress happens when both nutrients are present in good amounts.
Selenium works closely with iodine too, especially in the thyroid. Iodine helps make thyroid hormone, while selenium-dependent enzymes help activate it. This partnership needs balance, too much of either mineral might cause problems with the other.
Research suggests selenium, vitamin E and vitamin C might work better together to fight atherosclerosis than any single antioxidant. Each nutrient has its own job and works in different parts of cells. Vitamin E works in fats, vitamin C in water and selenium helps enzymes break down harmful compounds in fats.
Scientists keep learning more about selenium’s role in our bodies. This essential trace mineral remains the life-blood of many biological systems. From fighting oxidation to controlling thyroid function, supporting immunity to helping reproduction, selenium shows how even tiny amounts of nutrients can greatly affect our health and longevity.
7 essential selenium benefits we should know
Selenium does more than just its simple functions. This powerful trace mineral offers unique health benefits that boost longevity and overall wellbeing. Scientists keep discovering how it helps multiple body systems through its special properties.
1. Protects cells from oxidative stress
Selenium is the life-blood of antioxidant defense. It neutralizes harmful free radicals and reactive oxygen species. Our body’s selenoproteins, especially glutathione peroxidases, break down peroxides that could damage tissues and DNA.
Selenoproteins get rid of excess free radicals to protect cells from oxidative damage. Selenium acts as a catalyst in redox-based reactions throughout our body, including the cell, blood and intestine. Our body needs this because unchecked oxidative stress creates inflammation and health issues.
Research shows selenium’s antioxidant effects can reduce oxidative stress from physical exercise. The right selenium levels help protect r cells from daily oxidative challenges.
2. Helps regulate thyroid hormones
Our thyroid gland has the highest selenium concentration in the body. This vital mineral helps with thyroid hormone metabolism through selenoproteins.
Our body needs selenium to make selenoproteins. These proteins convert inactive thyroid hormone (T4) into its active form (T3). Selenium helps iodothyronine deiodinases work properly during this conversion.
Low selenium levels decrease thyroid hormone production because selenoproteins don’t work well. People with autoimmune thyroiditis who take selenium supplements show lower antibody levels, better thyroid ultrasound results and improved quality of life.
3. Boosts immune system performance
Selenium is vital for both innate and adaptive immune responses. Research shows higher blood selenium levels link to better immune function.
The right selenium levels (60–175 ng Se/mL plasma) help reduce inflammation throughout our body. Low levels harm immune cell function and slow down immune response.
Selenium improves immunity in several ways by affecting:
- Neutrophils and macrophages;
- Natural killer cells;
- T and B-lymphocytes.
People with HIV, influenza, tuberculosis and hepatitis C can boost their immunity with selenium supplements. It might also help reduce asthma symptoms thanks to its anti-inflammatory properties.
4. Supports reproductive health
Both men and women need selenium for reproductive health. Women benefit from selenium’s antioxidant properties that protect uterine health and reduce oxidative stress, which can affect embryo implantation and pregnancy.
Research links higher blood selenium to more antioxidants in follicular fluid, which helps reduce oxidative damage. Women who don’t get enough selenium in their diet face higher risks of sporadic anovulation.
Selenium plays key roles during pregnancy. It helps trophoblast cells grow and move. These cells create the blastocyst’s outer layer and reduce mitochondrial oxidative stress. Not getting enough selenium while pregnant might lead to miscarriage and harm the baby’s nervous and immune systems.
5. May reduce heart disease risk
Research points to selenium’s heart-protective benefits. People who eat moderate amounts of selenium showed a 16% lower risk of cardiovascular disease compared to those who ate the least.
Moderate selenium intake reduces risks of:
- Coronary heart disease by 20%;
- Congestive heart failure by 30%;
- Heart attacks by 25%;
- Angina by 30%.
These benefits come from selenium’s role in selenoproteins like glutathione peroxidases and thioredoxin reductases. These proteins fight oxidative stress that leads to heart disease.
6. Promotes brain and memory health
Scientists have found exciting ways selenium helps cognitive function. Animal studies show selenium supplements increased neuron growth and improved thinking in older mice. Research proved selenium could reverse age-related cognitive decline.
Scientists tested how selenium affects cognitive problems after stroke. Mice with stroke-related learning and memory issues recovered normal cognitive function with selenium supplements.
Low selenium levels might link to brain conditions. People with Alzheimer’s disease often have less selenium in their blood. Selenium helps brain signaling that affects memory and thinking, so keeping good levels matters for long-term brain health, according to research.
7. Aids detox and slows aging
Our body’s antioxidant defenses fight damage from reactive oxygen species as we age. Selenium’s antioxidant properties help balance this process and might slow aging.
Science suggests several ways selenium helps longevity. A 2020 study linked more dietary selenium to longer telomeres, DNA caps that affect cell aging. People over 45 showed 0.42% longer telomeres for every 20 microgram increase in dietary selenium.
Selenium helps manage and remove misfolded proteins linked to conditions like Alzheimer’s disease and type 2 diabetes. Studies show selenium offers valuable skincare and anti-aging benefits by activating antioxidant enzymes that protect against UV damage.
These benefits make selenium a vital nutrient that maintains health and might help us live longer.
Where to get selenium from food
Getting enough selenium from food is vital to staying healthy since our bodies can’t make this essential trace mineral. We need to know which foods have selenium and how much we should eat to maintain good levels without risking too much intake.
Top selenium-rich foods
Most selenium comes from protein-rich foods, though amounts change based on where they’re grown. Brazil nuts are the selenium champions. They pack an extraordinary 544 micrograms per ounce(about 6-8 nuts), almost 10 times what adults need daily. All the same, these nuts are so rich in selenium that one Brazil nut each day gives us about 95 micrograms.
Seafood gives us plenty of selenium too. Yellowfin tuna, sardines, shrimp and halibut are great sources as well.
Animal proteins reliably deliver selenium:
- Pork chop;
- Beef steak;
- Turkey;
- Chicken;
- Egg.
Plant options include enriched grains, like cooked spaghetti. Brown rice, baked beans and mushrooms help too. Americans get selenium mostly from everyday foods like breads, cereals, poultry and eggs. People who eat plant-based diets should watch their selenium intake more carefully.
How soil affects selenium in plants
Food’s selenium content changes based on where it grows because plants absorb selenium from soil. In fact, soil selenium levels can range from less than 0.01 μg/g to over 1,000 μg/g and plants reflect this huge difference. Crops from selenium-rich soils in South Dakota, Montana, Wyoming and several western states have more selenium than those from areas with less selenium.
Several things affect how much selenium soil has:
- Soil pH levels (which determine selenium forms);
- Organic matter content;
- Microbial activity;
- Moisture and texture;
- Temperature.
These factors explain why similar foods grown in different places can have different selenium amounts. Plants are our main selenium source worldwide, but their selenium content depends on how much they can take from soil.
Daily intake recommendations by age
Our recommended selenium intake changes with age. Children need more as they grow and adults need a stable amount:
| Age Group | Recommended Amount (mcg) |
|---|---|
| Birth to 6 months | 15 |
| Infants 7-12 months | 20 |
| Children 1-3 years | 20 |
| Children 4-8 years | 30 |
| Children 9-13 years | 40 |
| Teens and adults 14+ years | 55 |
| Pregnant individuals | 60 |
| Breastfeeding individuals | 70 |
The World Health Organization says adults shouldn’t take more than 0.3 mg/kg of selenium, with 55 μg daily being right for most people. We might not get enough selenium if we consume less than 50 μg each day.
Selenium deficiency isn’t common in the United States. Some groups need to watch their intake more carefully, especially people on kidney dialysis, those with HIV and anyone eating mostly plants grown in selenium-poor soils. These people should pay extra attention to getting enough selenium through food or supplements.
Selenium supplements: when and how to use them
If we can’t get enough selenium from food alone, supplements can help us maintain good levels of this vital mineral. The type of selenium in our supplement makes a big difference in how well our body absorbs and uses it.
Common forms: selenomethionine, selenite, selenium yeast
Selenium supplements come in several different forms that we can separate into organic or inorganic compounds. Our body absorbs up to about 90% of selenium from selenomethionine, selenium-enriched yeast, selenite and selenate. These options vary substantially in how well they work and how our body uses them.
Selenomethionine is the main organic form and it’s similar to the selenium naturally found in foods. Selenium-enriched yeast grows in selenium-rich conditions and offers another great organic option that our body absorbs well.
Sodium selenite and sodium selenate are inorganic forms that our body doesn’t absorb as well. Research shows us absorb about 90% of selenomethionine but only about 50% of selenium from selenite. These forms also work differently in our body:
| Form | Type | Bioavailability | Notable Properties |
|---|---|---|---|
| Selenomethionine | Organic | Highest (~90%) | Similar to food form, superior tissue retention |
| Selenium-enriched yeast | Organic | High (~90%) | Contains multiple organic selenium compounds |
| Sodium selenite | Inorganic | Moderate (~50%) | May cause oxidative stress |
| Sodium selenate | Inorganic | Moderate | Less commonly used in supplements |
Research suggests selenium-enriched yeast might work better than selenomethionine to name just one example in reducing prostate cancer risk. This happens even though selenomethionine is a major part of selenium-enriched yeast, which suggests other compounds in the yeast help make it effective.
Who might benefit from supplements
People in North America usually get enough selenium from their regular diet. All the same, some groups have a higher risk of not getting enough:
- People on kidney dialysis: hemodialysis removes some selenium from blood, which can lead to lower levels;
- People with HIV: they often show low selenium levels, possibly because they don’t absorb it well or don’t get enough;
- People eating mostly plants grown in selenium-poor soils: plants’ selenium content changes based on soil makeup.
Selenium deficiency is very rare in the United States and Canada. We might need supplements based on our health, where we live or what we eat.er risk of deficiency should talk to their doctor before taking more selenium.
Signs of selenium deficiency
Selenium plays a vital role in human health, yet its deficiency often goes undiagnosed until symptoms become obvious. We need to understand the warning signs, who’s at risk and how it affects our body to spot this nutritional gap early.
Symptoms to watch for
Our body shows several signs when it lacks selenium. These signs can affect many parts of our health. Here’s what to look for:
- Infertility in both men and women;
- Muscle weakness and pain;
- Persistent fatigue;
- Mental fog and cognitive difficulties;
- Hair loss;
- Thyroid dysfunction;
- Mood disturbances including anxiety and depression;
- Weakened immune system with increased susceptibility to illness.
Low selenium levels can lead to serious health issues. Keshan disease, a heart condition first found in 1935 in China’s selenium-poor regions, mostly affects women who can bear children and young kids. Another condition called Kashin-Beck disease damages bones, cartilage and joints. This disease appears in areas with low selenium in China, Tibet, Siberia and North Korea.
How deficiency affects body systems
Low selenium levels affect many body systems in different ways. The heart suffers through Keshan disease, which causes heart failure, enlargement and unusual ECG readings.
Our immune system weakens without enough selenium because selenoproteins can’t protect cells from damage. This deficiency can turn harmless viruses into dangerous ones. HIV patients’ CD4 counts drop as their selenium levels fall.
The reproductive system takes a big hit from low selenium. Men’s bodies need high selenium levels in their testicular tissue for making testosterone and healthy sperm.
Brain function changes when selenium runs low. People might feel down or act more aggressively. The brain gets first dibs on any available selenium, which shows how much our brain needs this mineral.
Low selenium alone might not make us sick right away, but it sets the stage for health problems when other stresses come along.
What science says: recent studies on selenium
Scientific investigations into selenium reveal a complex picture of its health effects. Studies show both promising results and unexpected limitations about selenium’s impact on the body.
Selenium and cancer prevention trials
Selenium’s relationship with cancer prevention has changed dramatically over time. The Nutritional Prevention of Cancer Trial showed promising results. Selenium supplementation reduced prostate cancer risk by 49-65% in men with lower baseline plasma selenium concentrations. We primarily focused on this early success which created substantial optimism about selenium’s potential as a cancer-fighting nutrient.
The later Selenium and Vitamin E Cancer Prevention Trial (SELECT) with 35,533 men showed different results. Researchers found no link between prostate cancer risk and supplementation with 200 mcg/day selenium. The study revealed that selenium supplementation might raise the risk of high-grade prostate cancer in men who already had higher baseline selenium levels.
Cognitive studies
Research shows increased dietary selenium intake relates to improved performance in immediate memory, executive function and processing speed. The connection varies based on hypertension status. Older adults with hypertension showed better cognitive performance with higher selenium intake substantially. Those without hypertension showed no notable differences.
Ongoing research and controversies
Scientists remain divided about optimal selenium recommendations. Research suggests selenium supplementation might increase type 2 diabetes risks, while other studies point to benefits in reducing inflammation. Researchers study whether selenium’s effects depend on individual genetic backgrounds, nutritional status and specific chemical forms.
Selenium shows us why balance matters so much in nutrition science. Our body thrives when we get just the right amount. Too much or too little can cause problems. This tiny mineral teaches a big lesson, the best nutrition isn’t about loading up on good things. The sweet spot lies in finding just the right amount that helps our body work at its best.
