THE EAT SMART, THINK SMART BRAIN ANTIAGING PLAN: FREE-RADICAL PATHOLOGY

Scientists have known for decades that free radicals (electrically charged atoms generated by every cell in the human body) attack the brain and central nervous system, damaging the delicate balance of chemistry and disrupting the fragile electronic network of nerves that allows us to think, feel, and act. Research over the past thirty years has implicated these atomic demons in a host of health problems, including memory loss, senility (including Alzheimer's disease), stroke, cancer, and massive nerve death that follows spinal-cord injury.

Free radicals are the price we pay for breathing, the inevitable consequence of living in a world where oxygen is the currency of nearly all life. Oxygen-related free radicals are a two-edged biological sword: We can't live with too many of them, and we can't live without enough of them. They are essential to a variety of metabolic reactions in the body involving the synthesis and metabolism of protein, fat, and carbohydrates. Our immune systems would be useless without the free radicals they generate to kill invading microbes. Left unchecked, however, free radicals can damage the delicate external framework of cells (called cell membranes or cell walls) and can cause cancer by injuring DNA, the genetic material that makes each of us unique.

A free radical is any atom that has an unpaired electron, an electrically charged particle that relentlessly searches for another electron "mate" to maintain stability and neutrality. When seemingly harmless substances, such as vegetable oil (or the highly unsaturated fats that make up brain cells), come in contact with free radicals, a chain reaction, or domino effect, may occur, creating thousands of additional free radicals that damage just about anything they touch. Free radicals cause fats to go rancid, turn bread into toast, turn a healthy brain into a senile one, and transform normal cells into cancerous ones.

Scientists first realized how free-radical damage could harm the brain by studying the hazards of radiation, particularly the type we receive from medical X-ray procedures. When X rays slam into the body, they split water molecules (most cells are about 90 percent water) into weak hydrogen-free radicals and extraordinarily destructive hydroxyl (one part oxygen and one part hydrogen) radicals. These hydroxyl radicals can destroy cell membranes in the brain and other organs, causing wholesale collapse of the cells; at the same time, they destroy the enzymes that repair DNA, which eventually leads to cancer.

In the late 1960s, scientists discovered one of the body's own defense systems against free radicals. This enzyme system, called SOD (superoxide dismutase), whose sole purpose is to neutralize a free radical called superoxide (a highly charged form of oxygen), plays an important role in the body's metabolism. It was then that scientists found that free radicals arise in the body not just under conditions of radioactive exposure, but during the daily processing of proteins, fats, and carbohydrates. In the mitochondria, the energy furnace of each cell, oxygen helps convert the digested foods we eat into usable fuel for the body, a process that ordinarily produces free radicals. Most of the free radicals are put to friendly metabolic purposes, such as building new biochemicals; others are neutralized by antioxidant systems, such as SOD. As it turns out, the mitochondrial membranes and their contents are especially susceptible to free-radical damage, and scientists now suspect that mitochondrial decay provides the origin of such age-related brain disorders as Parkinson's disease and senility.

Some white blood cells use free radicals to kill foreign microbes that invade the body. This type of free-radical production, however, is kept under tight control, eliminating the potential for cellular damage. A number of inflammatory conditions, including arthritis and severe infection, however, can cause white blood cells to gather and linger at the site of injury, leading to an abundance of free radicals that damage nearby cells.

Ordinary nutrients, particularly the minerals iron and copper, can react precipitously with oxygen to create free radicals, which is why the body ordinarily protects its stores of these metals from coming in contact with cells (the molecule hemoglobin, which carries oxygen in red blood cells, for example, keeps iron snugly sheltered in a molecular cage that prevents the formation of free radicals). If iron becomes detached from its safe harbor, as occurs with trauma or injury, it can set off a chain reaction of free radicals that can pose a greater risk to a person than the initial wound. Even more dangerous may be the iron overload caused by eating iron-fortified foods and vitamin-mineral supplements. This insidious form of iron supplementation (iron is intentionally added to many commercially made food products, such as breads, packaged cereals, and vitamin supplements) may overload the body's capacity to handle the mineral, resulting in health problems, such as heart disease, stroke, and brain and nerve damage.

Researchers have recently suggested that one reason why premenopausal women are less susceptible to heart disease and stroke than are men is that women lose a great deal of iron through menstruation and hence carry much less iron in their blood. Mounting evidence now reveals that cholesterol carried in the blood becomes "toxic" (causes damage to the arteries with a consequent buildup of plaque) when it is transformed (oxidized) by free radicals and that this free-radical chain reaction may damage arteries and set the stage for heart attacks and strokes.

Scientists now know that cigarette smoke (especially side-stream, or secondhand smoke), air travel (exposure to cosmic rays at high altitudes), a high intake of polyunsaturated fats (their molecular structure renders them highly susceptible to free-radical formation), X rays, air pollution, ordinary metabolism, and even exercise all produce free-radical chain reactions in the body. Given the ubiquity of free radicals, what can you do to protect your mind and body against these molecular terminators?

*21\244\2*