Americans have long been searching for the secret to eternal youth. There are dozens of theories that have been proposed, but one definitive answer continues to elude us. One of the most popular theories is the free-radical theory.

Dr. Denham Harman of the University of Nebraska College of Medicine first developed this theory, considered an exciting development in anti-aging research, in 1954. "Free radical" refers to any molecule that differs from normal molecules in possessing a free electron. The possession of a free electron makes a molecule react with its compatriots in highly explosive and destructive ways.

In conventional molecules, electrons come in pairs and their electrical charges balance each other out. Atoms with missing electrons bond with other atoms missing electrons, again creating a stable molecule. Free radicals, however, have an extra molecule, resulting in a negative charge. They seek to attach themselves to other molecules to steal an additional electron. Some free radical activity is necessary to transmit nerve impulses, synthesize hormones, maintain immunity, produce energy and even to contract muscles. This behavior can be destructive to the body, however.

Free radicals attack the structure of cell membranes creating metabolic waste products, which can darken the skin in certain areas (known as "aging spots"). They can also interfere with synthesis of protein (lowering our energy levels and preventing the body from building muscle mass) and harm cellular enzymes needed for chemical processes.

Free radical activity occurs throughout our lifetimes. As we age, they begin to take a greater toll. They disrupt cell metabolism and could create irregular cells, leading to cancer and death. They also attack collagen and elastin, causing wrinkles.