We know that aging isn't caused by one factor, Denham Harman, M.D., of the University of Nebraska College of Medicine, has collected data in support of his theory that aging is caused by free radicals. Free radicals are highly unstable molecules that seek out and attack other molecules in your body, such as fats, proteins, and the genetic material in your cells.
The key element in the production of free radicals is oxygen. As your body performs its millions of chemical interactions in the presence of oxygen, free radicals are generated as a byproduct. The environment also contains numerous substances that give us free radicals directly or cause us to create them as a byproduct of fighting off toxins. Each time your body defends itself against a free radical, a new free radical is produced, unleashing a chain reaction that can severely damage or destroy your tissues.
Dr. Harman found that free radicals are implicated in such diseases as atherosclerosis, hypertension, Alzheimer's disease, arthritis, late-onset diabetes, and Parkinson's disease. You can see that free radicals have a far-reaching effect on our bodies — if we let them.
Since oxidation causes free radicals, the solution is an antioxidant. Your body has built-in antioxidant defenses composed of enzymes, vitamins A, C, E, and beta-carotene, and trace minerals such as selenium and zinc. Each plays a different role in your health.
* Beta-carotene (which your body converts to vitamin A) protects the lipid (fat) portion of cells, such as cell membranes, from free-radical damage.
* Vitamin C protects the body's watery components, such as the fluid of the blood, against free-radical attacks. It also restores oxidized vitamin E to its active state.
* Vitamin E prevents cholesterol from being oxidized, or converted into its artery-damaging form. Like beta-carotene, it also protects cell membranes from free-radical damage.
* Selenium is a powerful antioxidant in its own right but is also an essential component of the antioxidant enzyme glutathione peroxidase, which protects against free-radical damage to cell membranes.
* Zinc plays a critical role in immune function, and is involved in more enzymatic reactions than any other mineral.
As we age, our levels of naturally produced antioxidants decline. At middle age, we experience a particularly steep drop in the body's primary antioxidant, glutathione. From that point on, we live in a state of chronic antioxidant deficiency, which continues as we age.
To slow the rate at which we age and reverse much of the damage that aging has already inflicted, we should use antioxidants to counteract the deficiency in our bodies. Antioxidants will put out the "free-radical fire" by interrupting the damaging chain reaction started by free radicals and neutralize free radicals before they have a chance to do damage.
You must give your body ample amounts of antioxidants every day in two ways: by eating antioxidant-rich foods, such as carrots, oranges, leafy greens, nuts, brown rice, and beans, to list only a few, and by taking nutritional supplements. Remember, it's virtually impossible to eat the quantities of food you'd need to get optimal levels of each antioxidant. It's not enough just to consume the Food and Drug Administration's recommended dietary allowance (RDA).
The government's RDAs are of little value in preventing age-related deterioration. My advice is to ignore them. Instead, I recommend that you take enough antioxidants at doses that research has shown to be effective at neutralizing free radicals, which, in some cases, is many times the RDA level.
Here's an overview of the antioxidant doses you should be getting in your multivitamin:
Vitamin A: 5,000 mg
Vitamin C: 2,650 mg
Beta-carotene: 15,000 IU
Vitamin E: 800 IU
Selenium: 200 mcg
Zinc: 30 mg