Overview
Selenium, a trace mineral essential to human health, plays a central role in numerous bodily functions, from bolstering the immune system to supporting cognitive health.
Despite its importance, selenium often flies under the radar in discussions about nutrition. This potent antioxidant combats oxidative stress, which is closely linked to aging and chronic diseases, and supports thyroid function, crucial for metabolism and energy production.
One compelling aspect of selenium is its broad spectrum of health benefits. Research indicates that consistent and adequate selenium intake can reduce the risk of certain cancers, support heart health, and enhance fertility. Its role in cognitive health is particularly noteworthy, with studies suggesting that selenium may slow cognitive decline in the elderly and improve overall mental function.
However, balance is key. Both selenium deficiency and excess can lead to serious health issues. Therefore, understanding the best dietary sources and recommended intake levels is crucial for reaping its benefits safely. Foods like Brazil nuts, seafood, beef, and organ meats are rich in selenium, while whole wheat bread, mushrooms, sunflower seeds, and cheese also help meet daily needs.
Ready to harness the power of selenium? Dive into this article to discover the countless health benefits of this essential mineral and explore a variety of selenium-rich foods to improve your diet and promote a healthier life!
How Much Selenium We Need Per Day?
The recommended dietary intake of selenium varies by age, gender, and life stage. For adult men and women, the Recommended Dietary Allowance (RDA) is 55 micrograms (mcg) per day. Pregnant women should aim for 60 mcg daily, while lactating women require 70 mcg per day.(1)
Infants and children need less selenium, with recommendations ranging from 15 mcg per day for infants to 40 mcg for adolescents aged 14-18 years.(1)
These guidelines are designed to meet the nutritional needs of almost all healthy individuals and to prevent selenium deficiency, which can lead to health issues such as Keshan disease, hypothyroidism, fatigue, weakness, weakened immune function, changes in hair and nails, and infertility.
It is important to obtain selenium through a balanced diet, as both deficiency and excessive intake can have adverse effects. The Tolerable Upper Intake Level (UL) for selenium is set at 400 mcg per day for adults to prevent toxicity.
In summary, maintaining appropriate selenium levels through a balanced diet is vital for overall health. For most people, this means enjoying selenium-rich foods like Brazil nuts, seafood, and whole grains in moderation.
Health Benefits of Selenium
1. Protects The Body Against Oxidative Damage
Selenium plays a critical role in maintaining health through its potent antioxidant and anti-inflammatory effects. Oxidative stress is a major contributor to serious diseases like heart disease, cancer, neurodegenerative disorders, and premature aging. Selenium is vital for the body's antioxidant defense system, protecting against oxidative stress caused by excess reactive oxygen species (ROS).
Selenium is an essential component of potent antioxidant enzymes like Glutathione peroxidase and Thioredoxin reductase. These enzymes convert harmful molecules into non-toxic compounds through a series of chemical reactions, preventing oxidative damage to cell membranes, proteins, and DNA.(2)
Furthermore, research demonstrates that selenium can regenerate other antioxidants. For instance, selenium-dependent enzymes such as glutathione peroxidases help recycle oxidized forms of vitamin C and vitamin E back to their active antioxidant forms, maintaining their antioxidant capacity within cells.
Selenium combats oxidative stress, reducing the risk of diseases like heart disease and cancer. It is a key component of enzymes like Glutathione peroxidase, which neutralize harmful molecules and regenerate other antioxidants such as vitamins C and E.
2. Essential For Your Thyroid Gland
Although iodine is widely known for its critical role in thyroid function, selenium is equally important in maintaining normal thyroid hormone production. The thyroid contains more selenium than any other organ in the body.(3)
Selenium is integral to thyroid hormone metabolism, particularly in the synthesis of T3 and T4 hormones. It is a component of selenoproteins, including the enzyme thyroid peroxidase (TPO), which catalyzes the iodination of thyroglobulin and the coupling of iodotyrosines to form thyroid hormones. Without sufficient selenium, TPO activity can be impaired, leading to reduced thyroid hormone production.
Selenium deficiency over time can disrupt thyroid hormone regulation, potentially causing conditions like hypothyroidism and autoimmune disorders such as Hashimoto's thyroiditis and Graves' disease. Selenium supplementation can help alleviate symptoms in these conditions, promoting better thyroid health and overall well-being.
Selenium is essential for thyroid health, aiding in the production of thyroid hormones T3 and T4 through its role in selenoproteins like thyroid peroxidase (TPO). Adequate selenium prevents hypothyroidism and autoimmune thyroid disorders such as Hashimoto's thyroiditis and Graves' disease.
3. May Help Treat Thyroid Disorders
Graves' disease and Hashimoto's thyroiditis are two major autoimmune disorders affecting the thyroid gland. Graves' disease leads to the overproduction of thyroid hormones (hyperthyroidism), while Hashimoto's thyroiditis typically results in the underproduction of these hormones (hypothyroidism) due to inflammation and gradual destruction of thyroid tissue.
Research indicates that selenium can serve as an effective adjuvant treatment for these conditions. Selenium is integral to the production of selenoproteins, which are crucial for regulating oxidative stress and maintaining immune function.
A study published in the Journal of Clinical Endocrinology & Metabolism reported that selenium supplementation significantly reduced thyroid peroxidase antibody (TPOAb) levels in patients with autoimmune thyroiditis, suggesting selenium's role in reducing thyroid autoimmunity and improving thyroid function.
Another study in the European Thyroid Journal indicated that selenium supplementation could reduce thyroid peroxidase antibodies and improve thyroid function in patients with Hashimoto's thyroiditis.
Furthermore, clinical trials have demonstrated that selenium's anti-inflammatory properties can improve overall thyroid health and alleviate symptoms in individuals suffering from autoimmune thyroid diseases.
By modulating the immune response and supporting antioxidant defenses, selenium plays a critical role in managing the symptoms and progression of both Graves' disease and Hashimoto's thyroiditis, offering a promising complement to conventional therapies.
4. Aids in The Detoxification of Heavy Metals
Selenium (Se) has demonstrated significant protective effects against the toxicity of heavy metals such as cadmium, mercury, thallium, and, to a lesser extent, silver. Selenium forms stable complexes with these metals, resulting in less toxic compounds that are excreted more efficiently from the body, thereby reducing their bioavailability and toxicity.(4)(5)(6)
Additionally, selenium enhances the body's defense against heavy metals by promoting the production of metallothioneins. These cysteine-rich proteins have a high affinity for binding heavy metals like mercury and cadmium, sequestering them, and preventing harmful effects on tissues and organs.
Selenium's potent antioxidant properties provide another layer of protection. As a critical component of antioxidant enzymes like glutathione peroxidase and thioredoxin reductase, selenium helps neutralize free radicals and repair oxidative damage induced by heavy metals. This antioxidant action safeguards cellular structures and functions from metal-induced oxidative damage.
Selenium aids in detoxifying heavy metals like cadmium and mercury by forming less toxic compounds that are excreted efficiently. It also boosts metallothionein production, which binds and sequesters these metals, preventing tissue damage.
5. May Reduce The Risk of Certain Cancers
Cancer arises when cellular DNA is persistently exposed to toxic elements, particularly free radicals, which induce oxidative stress, accelerate aging, and contribute to cancer development.(7)
Several studies have suggested a connection between selenium intake and a reduced risk of certain cancers. Selenium's anti-carcinogenic properties are primarily attributed to its role in antioxidant selenoproteins, which help regulate cell proliferation, energy metabolism, and the immune response, all of which are critical factors during tumorigenesis.(8)
For instance, research indicates that selenium supplementation may be beneficial in preventing and managing thyroid cancer, although more extensive studies are required to establish a definitive link.
Additionally, selenium's potential benefits extend to other cancer types, such as prostate, colorectal, and lung cancers. That being said, recent findings suggest that while selenium might lower cancer risk, excessive and uncontrolled dosages could have adverse effects. Thus, maintaining appropriate selenium levels is essential for maximizing its benefits while minimizing potential risks.
6. May Optimize Your Heart Function
A selenium-rich diet is crucial for maintaining heart health, while low selenium levels may increase the risk of heart and coronary diseases. An analysis of 25 observational studies found that a 50% increase in blood selenium levels was associated with a 24% reduction in heart disease risk.(9)
Selenium reduces the risk of heart disease through its anti-inflammatory properties, particularly by lowering markers such as C-reactive protein (CRP) and pro-inflammatory cytokines. A review of 16 controlled studies involving over 433,000 participants with heart disease showed that selenium supplementation significantly decreased CRP levels.
Oxidative stress, caused by an excess of free radicals, can lead to atherosclerosis—a condition where lipid plaques build up in the arteries, potentially causing strokes, heart attacks, and sudden death. Selenium's antioxidant properties counteract oxidative stress primarily through promoting glutathione peroxidase, an enzyme that helps neutralize free radicals and prevent cellular damage.
In summary, a diet rich in selenium helps maintain strong antioxidant defenses and minimizes inflammation and oxidative stress, thereby reducing the risk of heart disease. Foods high in selenium, such as Brazil nuts, seafood, and whole grains, can help ensure adequate intake of this vital mineral.
7. Boosts and Preserves Fertility
Several studies have linked selenium intake to improved fertility and reduced procreation disorders. Adequate selenium levels may decrease the risk of gestational complications, miscarriage, and low birth weight in newborns.(10)
For example, one study found that selenium supplementation in pregnant women led to a lower incidence of preeclampsia, a condition characterized by high blood pressure and potential organ damage during pregnancy.
For men, selenium is crucial for maintaining semen quality and sperm motility. Research indicates that selenium deficiency is associated with male infertility, often presenting as abnormal sperm morphology and decreased sperm motility. One study demonstrated that selenium supplementation improved sperm motility and function in infertile men.
Given these findings, ensuring adequate selenium intake is important for both men and women during their reproductive years. The recommended daily intake increases to 60 mcg during pregnancy and 70 mcg during breastfeeding to support fetal development and maternal health.
8. Supports Brain Health and Reduces Cognitive Decline
Selenium has been extensively studied for its potential benefits in cognitive function, particularly in reducing the risk and symptoms of cognitive decline in the elderly. A meta-analysis highlighted selenium supplementation's effectiveness in mitigating symptoms of Alzheimer's disease and mild cognitive decline, attributed to its potent antioxidant properties that combat oxidative stress, a major factor in cognitive impairment.
Another randomized controlled trial published in The American Journal of Clinical Nutrition found that elderly participants who took selenium supplements for six months experienced a significantly slower rate of cognitive decline compared to those who did not. This underscores selenium's protective role against age-related cognitive deterioration.
Moreover, selenium is crucial for the production and metabolism of neurotransmitters, which are essential for memory, learning, and mood regulation. Its role in maintaining neurotransmitter balance supports overall cognitive processes.
Additionally, selenium is vital for thyroid function, which significantly impacts metabolism and cognitive health. Adequate selenium levels support thyroid health, indirectly enhancing cognitive performance.
For instance, one review article showed that elderly individuals with sufficient selenium intake had better thyroid function and, consequently, better cognitive performance.
In summary, selenium's antioxidant properties, support for neurotransmitter production, and thyroid function contribute to its potential in reducing cognitive decline and supporting overall brain health in the elderly.
9. Promotes Skin Health
Selenium deficiency, affecting about one billion people worldwide, can significantly impact overall health, particularly skin health. It can lead to skin imperfections, poor appearance, and contribute to various dermatological issues such as dermatitis and psoriasis.
Aging is often characterized by an imbalance between the damage caused by reactive oxygen species (ROS) and the body's antioxidative defenses. Selenium, with its remarkable antioxidant and immune-boosting properties, helps maintain this balance, thereby potentially improving the aging process and promoting healthier skin.
Additionally, selenium protects the skin from harmful ultraviolet (UV) radiation. An animal study documented by the Office of Scientific and Technical Information (OSTI) demonstrated that selenium supplementation reduced UV-induced skin carcinogenesis in mice. This protection is attributed to selenium's ability to enhance antioxidant defenses and mitigate oxidative stress.
Furthermore, selenium aids in skin healing and reduces inflammation. Clinical trials have shown that selenium can boost the immune response and improve defense mechanisms in patients undergoing radiotherapy for head and neck cancer, thus benefiting skin health by reducing radiation-induced side effects like dermatitis. By supporting these various functions, selenium plays a crucial role in maintaining and enhancing skin health.
Zinc-Rich Foods Chart
Nuts and Seeds
- Brazil Nuts: 272 mcg per half-ounce (3-4 nuts)
- Sunflower Seeds: 19 mcg per ounce
Seafood
- Yellowfin Tuna: 92 mcg per 3 ounces
- Sardines: 45 mcg per 3 ounces
- Salmon: 40-65 mcg per 3 ounces
- Halibut: 47 mcg per 3 ounces
- Oysters: 40-65 mcg per 3 ounces
- Shrimp: 34 mcg per 3 ounces
Meat and Poultry
- Beef Liver: 28 mcg per 3 ounces
- Turkey: 31 mcg per 3 ounces
- Chicken: 22-25 mcg per 3 ounces
- Lamb: 20-30 mcg per 3 ounces
Dairy and Eggs
- Cottage Cheese: 20 mcg per 1 cup
- Eggs: 15 mcg per egg
- Yogurt: 8 mcg per 6 ounces
- Cheese: 10-20 mcg per ounce, depending on the type
Grains and Legumes
- Brown Rice: 19 mcg per cup (cooked)
- Whole Wheat Bread: 10 mcg per slice
- Oatmeal: 13 mcg per cup (cooked)
- Baked Beans: 13 mcg per cup
Vegetables
- Mushrooms: 12 mcg per 100 grams
Fruits
- Bananas: 1.2 mcg per medium banana
Keep in Mind...
The selenium content in these foods can vary based on soil selenium levels where the plants are grown or animals are raised.
It's crucial to balance selenium intake, as both deficiency and excess can lead to health issues.
Incorporating a variety of these selenium-rich foods into your diet can help ensure you meet the recommended daily intake for selenium, which is 55 mcg for adult men and women.
Brazil nuts are extremely high in selenium, so it's important to limit consumption to 1-3 nuts per day to avoid toxicity. Always check the packaging for specific selenium content, as it can vary.