Minerals
Selenium
An essential trace mineral vital for antioxidant defense, thyroid function, immune health, and DNA synthesis
Quick Facts
Daily Needs
55 mcg for adults, with variations based on age, sex, and life stage
Importance
Selenium is essential for antioxidant function, thyroid hormone metabolism, immune system regulation, DNA synthesis, and reproductive health.
Key Functions
- •Antioxidant protection via selenoproteins
- •Thyroid hormone metabolism
- •Immune system function
- •DNA synthesis and repair
- •Reproductive health
- •Cognitive function
- •Cardiovascular protection
- •Heavy metal detoxification
- •Inflammation modulation
- •Cancer risk reduction
Deficiency Signs
- •Weakened immune function
- •Thyroid dysfunction
- •Fatigue and weakness
- •Hair loss
- •Nail changes and brittleness
- •Cognitive decline
- •Reproductive issues (decreased fertility)
- •Muscle weakness and pain
- •Heart problems
- •In severe cases, Keshan disease (cardiomyopathy)
- •In severe cases, Kashin-Beck disease (osteoarthropathy)
Excess Signs
- •Garlic-like breath odor
- •Metallic taste in mouth
- •Hair and nail brittleness and loss
- •Skin lesions and rash
- •Nausea and vomiting
- •Fatigue and irritability
- •Nerve damage
- •Liver and kidney problems
- •Diabetes-like symptoms
- •Selenosis (severe toxicity)
Best Food Sources
- •Brazil nuts (highest natural source)
- •Seafood (tuna, sardines, oysters)
- •Organ meats (liver, kidney)
- •Meat and poultry
- •Eggs
- •Cereals and grains (particularly if grown in selenium-rich soil)
- •Mushrooms
- •Seeds and nuts
- •Legumes
- •Dairy products
Absorption Facts
- •Absorption efficiency is generally high (55-70%)
- •Selenomethionine (organic form) is better absorbed than inorganic forms
- •High doses of sulfur-containing amino acids may reduce absorption
- •Extreme doses of vitamin C may reduce selenium utilization
- •Absorption decreases as intake increases
- •Seleno-compounds in foods have different bioavailability
- •Cooking has minimal effect on selenium content
- •Heavy metals (mercury, arsenic, cadmium) can interfere with selenium metabolism
Special Considerations
- •Selenium content in plant foods depends heavily on soil content
- •Brazil nuts vary dramatically in selenium content
- •Geographic location affects typical selenium intake
- •The range between adequate intake and toxicity is narrower than for many nutrients
- •Selenium works synergistically with vitamin E
- •Selenium supplements may interact with certain medications
- •HIV/AIDS may increase selenium requirements
- •Dialysis increases selenium losses
- •Different forms of selenium have different biological activities
About Selenium
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