When we were in college, a free radical was a hothead individual who incited the masses and destabilized the old guard. Nowadays, the association has shifted, but the theme remains the same.
In medicine, a free radical is a molecule with a single electron in its outer orbit. Highly charged and unstable, it avidly seeks out other molecules with electrons it can steal. In this process, called oxidation, the electron that was robbed of its mate becomes unpaired and repeats the felony. Unless checked, one free radical can generate hundreds of additional free-radical reactions, causing a string of damaged cells that can lead to aging, cataracts, heart disease, cancer and immune disorders.
We are loaded with free radicals. The act of burning oxygen for energy produces free radicals. Our livers generate free radicals in processing metabolic wastes and drugs. When our immune system attacks viruses or bacteria, our free radicals disarm and destroy the invaders.
We also generate free radicals when we don’t want to. Trauma, infection and aging all result in free-radical production that contributes to inflammation and cellular disruption. Many outside sources create these highly charged molecules as well — environmental pollutants, cigarette smoke, exhaust fumes, pesticides, herbicides, ozone and ionizing radiation, as well as heavy metals such as mercury, cadmium, lead and even iron.
As you can see, free radicals are dangerous but not always bad. The danger is when free radical production goes unchecked. For defense, Mother Nature created antioxidants.
Antioxidants: Free-radical Defenders
At 57, Linus Pauling was diagnosed with prostate cancer. The two-time Nobel Prize winner theorized that he could stabilize the malignant process if he saturated his prostate gland with the antioxidant vitamin C. Generally speaking, prostate cancer that begins at such an early age is highly aggressive and has claimed the lives of men in their relative youth. Pauling, however, survived with all faculties intact to the ripe old age of 93. In the process, he and his wife went year after year without succumbing to the common cold.
Free-radical quenchers, antioxidants include vitamins A, C and E; carotenoids, including beta-carotene (a plant precursor of vitamin A); and the minerals zinc, selenium, copper and manganese. Remember that free radicals are highly reactive, because the single unpaired electron desperately seeks a mate. The antioxidants donate an electron, satisfying the quest of the highly charged, destructive free radical. Even more impressive is the fact that antioxidants also can stop free radicals from forming in the first place.
The fewer free radicals you have to contend with and the more antioxidants you have working for you, the better your chances of good health. Hence, the advice to avoid cigarettes and pollution and to eat plenty of antioxidant-rich foods.
If you think this is just microscopic Trivial Pursuit, consider this: Despite enormous gains in the treatment of heart disease, it is still the No. 1 killer in the United States. The process we know as atherosclerotic cardiovascular disease begins as an inflammatory reaction in the walls of the arteries. Antioxidants serve to protect and stabilize the cell membranes of the arterial walls, rendering them less prone to damage when accosted by free radicals in cigarette smoke or oxidized cholesterol.
Many people — doctors among them — do not realize that cholesterol is quite benign when compared to oxidatively modified cholesterol. It is the latter molecule, already altered by a free-radical encounter, that gets under the skin of the arterial wall and initiates the process we know as atherosclerosis.
Vital Vitamin E
Vitamin E is the major antioxidant that protects our membranes. Several studies have demonstrated its role in protecting cholesterol from oxidation. When combined with other antioxidants, including vitamin C, beta-carotene and selenium, its effect is even stronger.
A number of epidemiologic studies document the benefits of vitamin E and other antioxidants in the reduction of heart disease, angina and cardiovascular mortality. In one well-known Harvard study, a group of 39,910 male health professionals took vitamin E supplements in doses of at least 100 IU daily for a minimum of two years. They had a 30 percent lower relative risk of coronary heart disease compared to men who did not take vitamin E supplements.
The Diet-Cancer Link
Many factors interplay in the development of cancer. It has been estimated that 80 percent to 90 percent of all cancer is environmentally induced, and more than one-third is caused by diet. Free radicals play a major role in the process of cancer initiation as well as cancer promotion. Numerous investigations have demonstrated that antioxidants can decrease cancer risk.
Hundreds of studies now have shown that the higher the level of antioxidants in the diet, particularly carotene, vitamin E and selenium, the lower the likelihood of developing cancer. Epidemiologic studies have demonstrated this relationship in cancers of the lung, larynx, bladder, esophagus, stomach, colon, prostate, cervix, thyroid, mouth and throat, as well as leukemia and lymphoma.
Antioxidants help protect against other conditions as well, including aging, Alzheimer’s, immune disorders, arthritis, diabetic complications and eye difficulties, including macular degeneration and cataracts. Studies suggest that these nutrients work best as a team. Vitamins C and E, selenium and carotene all assist each other in their important roles. There is evidence that beta-carotene, by itself, may not be beneficial. On the other hand, more than 500 carotenoids go to bat for you when you consume beta-carotene in a whole food, such as cantaloupe or spinach.
In other words, don’t look to vitamin and mineral supplements to meet all your antioxidant needs. I recommend a high intake of whole grains, vegetables and fruits because of the mix of antioxidants and other plant chemicals that perform their own magic to stop diseases before they develop.
Tomatoes, for example, contain lycopene, an antioxidant that protects DNA from toxic damage. A recent study demonstrated that individuals who have higher amounts of tomatoes and tomato sauce in their diet have a lower risk of cancer. Citrus fruits contain limonene, which boosts enzymes that dispose of cancer-causing substances. Green tea contains polyphenols (other potent antioxidants) and catechins, which help the liver rid the body of toxins.
Certain foods act as better cancer fighters than others — carrots and green, leafy vegetables appear to wage the good battle against lung cancer, while cruciferous vegetables fight against colon cancer. Fruit appears to be especially effective against cancers of the mouth and neck area, including esophageal cancer. Lettuce and onions help prevent stomach cancer.
Deeply colored vegetables and fruits generally contain more of the important nutrients than their paler cousins. For example, romaine lettuce is a much better source of carotene than iceberg lettuce. Many would argue it tastes better too, another good reason for choosing romaine.
As the primary detoxifying organ of the body, the liver has a particularly critical role in the prevention of chronic degenerative diseases, such as cancer, heart disease and arthritis. Living in the industrialized world, with its added exposures to drugs and environmental pollutants, has added quite a burden to our livers’ job description. Luckily, several other natural foods are ready to help out.
Garlic, onions, leeks and chives contain allyl sulfides, which help regulate liver enzymes and increase flush out carcinogens. Cruciferous vegetables, including broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, kohlrabi, turnips, rutabaga and mustard greens contain sulforaphane. These compounds boost the production of other enzymes, further carting off the dangerous residues that the first enzymes might have left behind. Other constituents of these vegetables, called indoles, stimulate enzymes that decrease estrogen activity and may reduce the risk of breast cancer.
Soybeans are a miracle food because of their action on so many fronts. Soy is replete with isoflavones, primarily genistein and diadzein. These are both antioxidants and plant estrogens. Plant estrogens’ weak estrogenic activity blocks the effect of natural estrogen and reduces risk of cancer of the breast and prostate. These same chemicals successfully benefit other menopausal problems, including osteoporosis and hot flashes.
Some proteins in soy suppress the production of enzymes in cancer cells and may slow tumor growth. Soy protein can also decrease cholesterol and the risk of heart disease. Saponins, found in soybeans and other dried beans, interfere with DNA production and inhibit tumor growth. In Eastern cultures, where soy is the primary dietary protein, the incidence of osteoporosis, heart disease and cancer is significantly less than in the United States.
In internal medicine training, we spent most of our time taking care of very sick people in the intensive and coronary units. While we did our best to stabilize them, in general their illnesses were too far advanced to cure anyone. Our chances of helping people are much greater if we can prevent something before it starts, rather than playing catch-up after it gets going.
The ounce of prevention is a good healthy diet and is far superior to a pound of drugs, surgery or chemotherapy. Along with regular exercise and a healthy attitude, an intelligent, informed diet is the best health insurance on the market.
Start your antioxidant adventure by discarding foods that do nothing (or those with negative health effects) and stocking up on health-building foods.
The French Paradox
Ever hear of the “French paradox?” French people have a relatively low rate of heart disease despite a high-fat diet, replete with cream sauces and croissants. Investigators believe the secret lies in the intake of wine, which contains high amounts of proanthocyanidins. These compounds, which belong to the flavonoid family, are found in bilberries, cranberries, black currants, green tea, black tea, grape juice and wine. They are also available as supplements, derived from pine bark or grape seeds. The main functions of proanthocyanidins are as antioxidants, and they serve to stabilize the walls of our blood vessels.
Adapted from The Antioxidant Save-Your-Life Cookbook by Jane Kinderlehrer and Daniel A. Kinderlehrer, M.D.; copyright 2000 . Reprinted by permission of Newmarket Press, 18 E. 48th St., New York, NY 10017; www.newmarketpress.com.