Catalase is dependent on iron as a cofactor, but excess iron can actually lead to increased free radical generation. Glutathione peroxidase depends on adequate selenium as well as adequate glutathione, a sulfur-containing amino acid derived from glutamine. A typical selenium dose is 200 mcg per day. Zinc levels decline with age in both animals and humans. As the thymus gland ages, it shrinks and loses its vigor in a process called involution resulting in decreased cellular immunity.
Zinc supplements prevent thymus involution and enhance the activity of the thymic hormone thymulin.
In elderly diabetic patients, zinc supplements can restore some deficits of T-cell function and thus enhance immunity. It is essential for energy production in the mitochondria, especially in the heart. It can reduce damage to the heart muscle in ischemic heart disease. Herbs and flavonoids can help prevent and treat age-related conditions, though it is impossible to thoroughly cover all of them in this review. 34 Memory loss is one of the most distressing signs of aging.