"Some people seem to stay young forever. They never lose their hair, their skin stays youthful, and they remain slim and physically active. Others go bald before they reach twenty, develop an extra layer of fat by thirty, and have deep wrinkles by forty. The assaults of time are not entirely due to genetics. Food can be part of the problem. And more important, certain foods contain natural ingredients that can help protect against aging.
"Since the 1950s a substantial body of evidence has shown how foods, properly selected, have a great deal of power to help us stay young. This evidence is now collectively known as the free radical theory of aging.
"While it was a heretical porposition in the 1950s, it is now widely accepted by scientists and nutritionists, who see free radicals as contributors to skin aging, cataracts, arthritis, and, perhaps, to the most basic aspects of the aging process.
"Certain foods slow the effects of time, while others speed them up. In addition, foods can change the amounts of hormones in the body. In turn, these hormones play a critical role in many bodily functions."
The changes that most of us attribute to the aging process actually have very little to do with the passage of time. Compare the skin on your face with the skin on the inside of your upper arm. The skin of your upper arm is not exposed to sun, and it keeps its youthfulness much longer. These protected skin cells also maintain more of their ability to grow and multiply. Sun damaged skin is nearer the end of its lifespan. Although the surface skin cells are constantly being replaced, the underlying skin becomes wrinkled and leathery and loses its resilience.
"Like all the cells of your body, your cells need oxygen. It is the very basis of animal life, including ours. But oxygen is biology's double-edged sword. As sunlight slowly bakes your skin, oxygen molecules often become extremely unstable. They pick up too many molecules, or carry electrons in unstable orbits. These destablilized molecules are called free radicals. They are also produced, but to a lesser degree, in the course of normal workings of the cell."
"The damaging effects of free radicals are not a recent discovery. Physician and researcher Dr. Denham Harman is a professor at the University of Nebraska School of Medicine and is head of the American Aging Association. In the 1950s, he was studying free radicals, which at the time were mainly of interest to chemists dealing with vats of industrial products. Harman suggested that free radical damage might play a part in the aging of the human body.
"One monring in November 1954, Dr. Harman was sitting in his office reading and suddenly it struck him that free radicals were not just in vats of chemicals in our factories and warehouses. They actually might be forming minute by minute in the blood coursing through our veins, attacking the insides of our arteries, aging our skin, sparking the cellular havoc of cancer. Could free radicals be the key to the aging processes? Could they play a role in cancer or heart disease?"
"'I spoke to people on the Berkeley campus about this possibility,' Dr. Harman said. Most thought it was simply an idea. But other researchers took an interest in the theory. There is now a huge body of research showing that free radical damage occurs every minute of the day in the human body. Evidence began to build up, Harman said, and now, about forty years later, many scientists accept this, both for disease processes and for aging."
"Plants would rapidly be damaged by the sun if they did not have one vital chemical in their leaves: beta-carotene. As the sun bears down on plant leaves, free radicals form just as they do in your skin, but beta-carotene removes the free radicals before they can do their damage. Beta-carotene is a vital chemical all chlorophyll-containing plants use to neutralize free radicals as they are formed.
"In the 1950s, another researcher in Berkeley, California, developed a mutant single-celled plant that lacked beta-carotene. When exposed to light and air, it was wiped out in short order.
"The technical term for a protective chemical like beta-carotene is antioxidant, meaning that it neutralizes free radicals and blocks the tissue oxidation that they could cause. Antioxidants work by allowing themselves to be attacked and damaged by free radicals, sparing the cell itself.
"As our ancestors plucked plants from the ground and fruit from the trees, they took beta-carotene for themselves. It passed into their bloodstream and became part of their own defense against toxic molecules. Today, when you add a leaf of spinach to a salad, or bite into a carrot, this natural chemical enters the cells of your body. You cannot feel it, but it is busy knocking out the free radicals that would age your skin or damage your heart or other organs.
"There are dozens of other antioxidants in plants, each with a slightly different role in protecting the body. In fact, there are dozens of relatives of beta-carotene, called carotenoids, found naturally in plants, and there are other vitamins in vegetables that work as the body's antioxidant team. In addition, consuming a concentration of one antioxidant may reduce the absorption of others. Vegetables, along with fruits, grains, and beans, provide nature's balanced mix of antioxidants.
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