Selenium

Why this ingredient is used

Selenium is a trace mineral that works with vitamin E as an antioxidant duo protecting cells from oxidative damage. It is essential for thyroid hormone metabolism and immune function. The selenium requirement for dogs and cats is tiny (0.3 mg per kg of food) but deficiency causes white muscle disease (myodegeneration) in puppies and kittens. Most commercial pet food adds sodium selenite or selenium yeast. Brazil nuts are the richest natural source but are not used in pet food. Selenium is often listed alongside vitamin E because they are synergistic: each enhances the other's antioxidant effect.