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Antioxidants: What are they and what do they do?




WHAT IS OXIDATION?


Oxidation is a reactive chemical process whereby one atom or molecule with an unpaired electron (usually a form of oxygen and often referred to as a “free radical”) robs an electron from another atom or molecule. Fire is one of the most literal or extreme examples of this process, demonstrating how potentially reactive and self-perpetuating oxidation can be. Oxidation, however, can also occur at a much slower rate and more subtly, such as in the rancidity of fats and oils or the yellowing of newsprint. Oxidation occurs in the presence of heat and/or light (energy), at a rate that depends upon fuel availability and levels of oxygen or other “oxidizers” etc.



Our bodies’ cells burn or “oxidize” food (carbohydrates, fats and proteins) in the presence of oxygen in the same manner, but our metabolism controls the “burn” of digested food to release much less of the resulting energy as heat and instead directs the released energy to run our biological machinery. In addition to the processes of metabolic energy production following digestion, oxidation also occurs randomly and perpetually throughout the body in a domino-like fashion. The fats/lipids present in our cell membranes are especially vulnerable. Once an atom or molecule is oxidized (has an electron stolen), it, in turn, steals an electron from another atom or molecule, and so on. The process runs amok.



IS OXYGEN THE ONLY CAUSE?


Generally, oxygen is the cause. However, our primary concern is what turns oxygen into a “free radical creator” in the first place. Our environment is a dangerous place when it comes to free radical producers: radiation, air pollution, pesticides, anesthetics, gasoline vapors, fried and char-broiled foods, drugs, solvents, alcohol, lead and mercury are just some of the offenders we deal with. The damage of sunburn is caused by the free radicals formed by UV light. One of the worst offenders is first- and second-hand cigarette smoke, producing literally billions of free radicals in just one “puff”.



SO ARE WE SAFE IF WE AVOID THESE THINGS?


Unfortunately, we are not. Day-to-day living generates free radicals. The normal metabolic reactions of the body are constantly creating free radicals—they are the byproducts of the regular construction/destruction of body tissues and the detoxification of drugs and wastes in the liver. Even heavy exercise causes a flood of free radicals.


Alternatively, our amazingly intelligent body utilizes the power and reactivity of free radicals for the good: the immune cells that patrol our blood and tissues for bacteria, viruses, cancer cells and other invaders make and use free radicals as their main ammunition to kill these intruders.



SINCE FREE RADICALS ARE EVERYWHERE, ARE WE DOOMED?


In a sense we are doomed. Many doctors and scientists support the theory that free radical damage is behind the process of aging where accumulated damage over a lifetime leads to an eventual breakdown of the glues that hold us together. Free radicals are also implicated in the pathogenesis of many diseases and conditions, including cancer, heart disease, arthritis, bursitis, lupus, other autoimmune diseases and inflammation. The body is not defenseless, however, creating and utilizing antioxidant atoms and molecules to quench these free radicals and thwart this ongoing process of oxidation. Antioxidants carry an extra electron along with them, searching the body for a free radical to give it to. Once accomplished, these antioxidant atoms and molecules are reusable, picking up another electron from a safe source without generating new free radicals, allowing them to perpetually perform their task.



WHERE DO ANTIOXIDANTS COME FROM?


Some antioxidants are proteins made by the body, and many others are delivered to us in the food we eat or supplements we take. The most important of these are vitamin C, vitamin E, beta-carotene (and the other carotenoids), bioflavonoids, selenium, zinc, and some amino acids. Food sources for these are listed below.



ARE FOOD SOURCES OF ANTIOXIDANTS ENOUGH?


While they are readily available from our foods, our antioxidant defense systems are vulnerable to nutritional deficiencies. Many health practitioners believe that the increased load of toxins in today's environment combined with the borderline diets we eat tip the oxidant/antioxidant balance against us. Antioxidant supplements can help tip the balance back in our favor and may slow the aging process.



MAJOR ANTIOXIDANT NUTRIENTS AND THEIR DIETARY SOURCES


Carotene(s)

Broccoli, cantaloupe, carrots (and juice), fresh or dried apricots, mangoes and persimmons, leafy greens (spinach, kale, mustard, collard, Swiss chard), pumpkin, winter squash, sweet potatoes, tomato products


Vitamin C

Blackberries, raspberries, strawberries, citrus fruits and juices (oranges and grapefruits), cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, kohlrabi, cabbage), leafy greens (mustard, turnip, kale, collard), melons (especially cantaloupe), papaya, kiwi, mangoes, pineapple, guava, strawberries, red and green peppers, sweet potatoes, tomatoes and tomato juice


Bioflavonoids

Apples, green tea, onions, cherries, blueberries, herbs (bilberry, hawthorne, chamomile, ginkgo, milk thistle), quercetin, and citrus (from the fleshy portion of the peel), green pepper


Vitamin E

Avocados, fish and shellfish, leafy greens (fresh spinach, kale, collard), mangoes, nuts, seeds, wheat germ, whole grain products, vegetable oils, egg yolk


Selenium & Zinc

Cashews, eggs, garlic, halibut, oysters, salmon, tuna, scallops

Oysters, crabmeat, cheese, beef roast, pumpkin seeds, dry roasted cashews, whole grains


Resources

  1. Levin, Buck, Environmental Nutrition, 1999, HingePin Integrative Learning Materials, Vashon Island WA

  2. Marz, Russell B. Medical Nutrition from Marz, 2nd Edition 1999, Omni-Press, Portland OR

  3. Schmidt, Michael A., Smart Fats, 1997, Frog Ltd. Berkeley CA

  4. Groff JL, Gropper SS, Advanced Nutrition and Human Metabolism, 3rd Edition 2000, Wadsworth Pulications

  5. Brown, Donald J., ND, Herbal Prescriptions for Health and Healing, 2000, Prima Health Publications, CA

  6. Pennington, Jean AT, PhD, RD, Bowes & Church’s Food Values of Portions Commonly Used, 7th Edition 1988, Lippincott Publications, NY

  7. Champe, Pamela C., Harvey, Richard A., Biochemistry, 2nd Edition 1994, Lippincott-Raven Publishers, PA

Here's to your health,

Dr. Mead

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