Selenium
This is an essential mineral known for its antioxidant capabilities; it is a component of certain antioxidant enzymes, such as glutathione, which provide protection. However, consuming excessive amounts can lead to oxidative damage and may be diabetic (meaning it may increase the risk of diabetes).
Selenium is most commonly used in immunity and infectious diseases. Selenium is also used for acne, chronic kidney disease, and six other health conditions and goals.
Dosage information
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Selenium (chemical symbol Se) is an essential trace mineral for the human body. The body cannot synthesize it and must obtain it through food (such as Brazil nuts, seafood, offal, and whole grains) or supplements. Although present in small amounts in the body, it is crucial for maintaining health.
- Powerful antioxidant: It is an important component of glutathione peroxidase, which helps neutralize free radicals, protects cells from oxidative damage, thereby delaying aging and reducing the risk of chronic diseases.
- Regulating thyroid function: The thyroid gland is one of the organs with the highest selenium content in the human body. Selenium assists in the metabolism and conversion of thyroid hormones (converting T4 into active T3), maintaining normal metabolism.
- Boosts the immune system: Selenium can stimulate the production of white blood cells, enhancing the body's ability to fight viral and bacterial infections.
- Protects the cardiovascular system: By reducing oxidative stress and inflammation, it helps lower the risk of heart disease.
- Reproductive health: For men, selenium is essential for sperm production and motility.
- Deficiency may lead to Keshan disease (cardiomyopathy), Kashin-Beck disease, decreased immunity, and hypothyroidism.
- Selenium poisoning (overdose): Initial symptoms: garlic-like (metallic) breath, hair loss, brittle or falling nails. Severe symptoms: gastrointestinal upset (nausea, diarrhea), fatigue, nervous system damage, skin rash. Extreme cases: kidney failure, heart failure, and even death.
Selenium protein synthesis: When we ingest selenium, our bodies combine it with proteins to form selenoproteins .
Enzyme Active Center: These selenoproteins are the "active center" of many antioxidant enzymes (such as glutathione peroxidase mentioned above). Just as a car needs a spark plug to start, these enzymes need selenium to activate their "toxin removal" and "antioxidant" functions. Without enough selenium, these protective mechanisms will shut down.
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Selenium effectively improves health problems
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Nutritional Supplement Recommendations
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Swanson, Selenium, 100 mcg, 300 capsules
Contains selenium (100 mcg) , which helps support antioxidant protection, a healthy immune system , and maintain normal thyroid function, making it a good choice for daily selenium supplementation.
NOW Foods, Selenium, 100 mcg, 250 tablets
Contains selenium (100 mcg) , which helps support antioxidant protection, a healthy immune system , and maintain normal thyroid function, making it a good choice for daily selenium supplementation.
Life Extension, Premium Selenium-Rich Vegetarian Capsules, containing Vitamin E, 200 mcg, 100 capsules per pack
This formula contains 200 mcg of selenium and vitamin E, providing antioxidant benefits that support antioxidant protection, a healthy immune system , and normal thyroid function. It is an excellent choice for daily selenium and antioxidant supplementation.
California Gold Nutrition, N-acetyl-L-cysteine with molybdenum and selenium, 120 vegetarian capsules
Containing N-acetyl L-Cysteine (NAC) along with molybdenum and selenium , it helps support antioxidant protection, detoxification function, immune system health , and maintenance of normal cell function, making it a good choice for daily antioxidant and nutritional supplementation.
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Dosage information
For specific health goals, research recommends intakes far exceeding basic requirements:
- Cancer prevention and overall health goals: In order to maintain optimal health and with particular emphasis on anti-carcinogenic properties , it is recommended that the total daily intake target be between 200 and 300 μg .
This dosage range refers to the "total intake ," which means that the content of food (such as Brazil nuts and seafood) and supplements must be calculated together, rather than referring to the dosage of supplements alone.
Most people should consume at least the recommended daily intake (RDA) of selenium (about 55 μg for adults), which includes the total amount obtained from all sources.
It is common to exceed the RDA for supplements, but it is very important not to exceed the tolerable upper intake level (UL) (usually 400 μg for adults) unless under the guidance and monitoring of a healthcare professional.
Not recommended to take with selenium
Reason: This is the most important contraindication for selenium absorption. High doses of vitamin C (ascorbic acid) will react chemically with inorganic selenium (such as sodium selenite, commonly found in general supplements) in the acidic environment of the stomach, reducing selenium to "elemental selenium" that cannot be absorbed by the intestines, leading to its excretion. Both of these will reduce the effectiveness of the vitamin C and vitamin C.
Note: If you are taking "organic selenium" (such as selenium yeast or selenomethionine), the impact is less, but to be on the safe side, it is generally recommended to separate them.
example:
High-potency Vitamin C effervescent tablets (1000mg)
Skin whitening and antioxidant supplement (containing high levels of Vitamin C)
At the same time, drink plenty of orange juice or lemon juice.
suggestion:
🕒 The two should be taken 2–3 hours apart. It is recommended to take Vitamin C after breakfast and Selenium after lunch or dinner.
Reason: Although many men’s health supplements combine zinc and selenium (with adjusted dosages), if you take high doses of zinc alone (for example, taking large amounts of zinc to help you recover from a cold), these two trace minerals will still compete for absorption in the intestines, which may reduce the bioavailability of selenium.
Note: The impact is not as severe as that of calcium and iron, but caution is needed when supplementing with high doses over a long period.
example:
High-dose zinc tablets (Zinc Gluconate/Picolinate)
suggestion:
🕒 It is recommended to take them separately, for example, take zinc with lunch and selenium with dinner, with an interval of 2 hours .
Unlike other vitamins, selenium is more dangerous in excess than in deficiency . This point must be emphasized to readers in this column.
1. Brazil Nuts — ⚠️ Very easy to consume in excess
- Reason: Brazil nuts are the food with the highest selenium content on Earth. Just 1-2 Brazil nuts can meet or exceed the recommended daily intake.
- Warning: If you are already taking selenium supplements, do not eat Brazil nuts . Otherwise, it can easily lead to selenium poisoning.
- Symptoms of poisoning: hair loss, brittle/falling nails, garlic breath, gastrointestinal discomfort, and nerve damage.
2. Anticoagulants/Antiplatelets
- Reason: Selenium itself has a mild anticoagulant effect. If taken with medications such as warfarin or aspirin, it may increase the risk of bleeding (such as nosebleeds or bruising).
- Recommendation: Selenium supplements should be discontinued two weeks before surgery.
3. Chemotherapy drugs (such as Cisplatin)
- Reason: Although some studies have explored whether selenium can reduce the side effects of chemotherapy, it may also reduce the cancer-killing effect of chemotherapy drugs .
- Recommendation: During cancer treatment, do not supplement with high doses of selenium without the explicit permission of an oncologist.
Safety Information and Side Effects
Risk warnings for specific groups, medical conditions, or long-term use:
- Selenium poisoning (Selenosis/Chronic Toxicity) Causes: Selenium has a narrow safe range; long-term excessive intake can easily lead to poisoning. Common symptoms: Garlic breath , hair loss, brittle or falling nails, rash, fatigue, irritability, and neurological abnormalities. Note: If nail or hair abnormalities occur, supplementation should be stopped immediately.
- History of skin cancer risk: Although selenium has antioxidant properties, a large clinical trial (NPC Trial) found that selenium supplementation may increase the risk of squamous cell carcinoma . Recommendation: Individuals with skin cancer or a related history should avoid long-term, high-dose supplementation.
- Diabetes Risk Observation: Some large studies (such as the SELECT trial) show that long-term use of selenium supplements (200 mcg daily) may slightly increase the risk of developing type 2 diabetes . High-risk group: This risk appears to be more pronounced in people whose selenium levels are already sufficient.
- Iodine Deficiency Interaction: Selenium and iodine are closely related in thyroid metabolism. Risk: Supplementing with selenium alone in the presence of iodine deficiency may worsen symptoms of hypothyroidism . Recommendation: Ensure adequate iodine intake before supplementing with selenium.
- Current status of prostate cancer: Selenium was previously thought to prevent prostate cancer, but subsequent large-scale studies (SELECT) showed no preventative effect. Warning: For individuals with already high baseline selenium levels, additional selenium supplementation may actually increase the risk of developing high-grade prostate cancer.
1. Pregnancy
- Safety Status: Safe. Prerequisite: Must be used within the recommended intake range.
- Importance: Selenium crosses the placenta and is crucial for fetal growth and development as well as for regulating maternal thyroid function.
- Upper Intake Level (UPL): Adults (including pregnant women) should not exceed 400 mcg per day. Warning: Very high doses of selenium have shown teratogenic effects in animal studies. Although human data are limited, pregnant women should strictly avoid consuming doses exceeding the upper limit.
2. Lactation
- Safety Status: Safe. Prerequisite: Must be used within the recommended intake range.
- Effects on breast milk: Selenium is secreted into breast milk. The concentration of selenium in breast milk is highly correlated with the mother's dietary intake; if the mother consumes too much selenium, the infant may ingest excessive amounts.
- Upper limit of intake: Same as during pregnancy, no more than 400 mcg per day.
