Which mineral is essential for antioxidant defense?

• A. Zinc
• B. Copper
• C. Iodine
• D. Selenium

Answer: (D)

Antioxidant defense relies on enzymes that neutralize reactive oxygen species, and some enzymes require trace minerals as cofactors. Selenium is essential because it is incorporated into selenoproteins such as glutathione peroxidases and thioredoxin reductases. Glutathione peroxidase specifically catalyzes the reduction of hydrogen peroxide and lipid peroxides, using glutathione to detoxify these reactive species. This direct detoxification activity is a central part of the cell’s antioxidant defense. Without enough selenium, these enzymes don’t function well, leading to increased oxidative stress and tissue damage, which is well documented in livestock as selenium deficiency disorders. While zinc and copper participate in antioxidant enzymes like Cu/Zn-superoxide dismutase, and iodine relates to thyroid metabolism rather than antioxidant defense, selenium’s role in glutathione peroxidase makes it the mineral most essential for antioxidant defense.