Zinc is one mineral that is often deficient in older folks no matter how they eat, which causes loss of taste, loss of smell and prostate difficulties in men. Zinc plays a major role in our immune system too and has been demonstrated in people over 70 to increase their T-cells which help to fight infection. Not well proven yet, but nevertheless likely, is the role that decreased zinc plays in causing blindness in the elderly. Low levels of zinc often result in low levels of thyroid hormone.
Adding zinc can produce many positive effects such as rejuvenating thymic function, improved immune response, improved smell and taste, reduced prostate problems, and improved male sexual function. Because melatonin aids the absorption of zinc in your intestines, then melatonin will also produce some of these benefits.
Although it is not proven yet, it seems as though adding melatonin and/or zinc can play a major role in reversing macular degeneration, a disease that usually results in complete blindness maong some elderly.
Zinc is cheap and is often sold in combination with other vitamins and minerals. For anti-aging pirposes, I recommend that you take 15+ mg/day as well as 2-3mg/day of melatonin