Selenium
Selenium is an essential trace mineral that plays a crucial role in maintaining immune function, thyroid health, and antioxidant defense mechanisms. It is particularly important for preventing oxidative damage to cells.
Selenium RDA (Recommended Dietary Allowance):
- Adults (19+ years): 55 µg/day
- Pregnant women: 60 µg/day
- Breastfeeding women: 70 µg/day
- Children (varies by age): 20-40 µg/day
ODA (Optimal Daily Allowance):
- 70-150 µg/day (depending on individual needs and health conditions)
Found in:
- Brazil nuts (highest natural source)
- Seafood (tuna, sardines, shrimp)
- Meat (beef, turkey, chicken)
- Eggs
- Whole grains (brown rice, oats, barley)
- Dairy products (milk, cheese, yogurt)
- Sunflower seeds
Helps with:
- Acting as a cofactor for glutathione peroxidase, an important antioxidant enzyme
- Supporting thyroid hormone metabolism and function
- Boosting immune system efficiency
- Protecting cells from oxidative stress and inflammation
- Reducing the risk of certain chronic diseases (e.g., heart disease)
Insufficient doses:
- Symptoms of deficiency:
- Fatigue or general weakness
- Weakened immune response
- Cognitive decline or mental fog
- Keshan disease (a type of heart disease linked to selenium deficiency)
- Kashin-Beck disease (a form of osteoarthritis in regions with low selenium levels)
- Increased susceptibility to oxidative damage
- Selenium deficiency is more common in areas with selenium-poor soils.
Excessive doses:
- Upper limit: 400 µg/day for adults
- Possible side effects of excessive intake:
- Selenosis (characterized by hair and nail loss, skin rashes, and gastrointestinal issues)
- Garlic-like odor in breath and metallic taste
- Neurological symptoms (e.g., irritability or numbness)
Interactions:
- Synergy:
- Antagonistic interactions:
- High doses may reduce the bioavailability of certain heavy metals, which is generally beneficial.
- Excessive zinc or copper intake can interfere with selenium absorption.