Antioxidants In Food

Antioxidants, naturally present in many foods, appear to benefit health overall. They are credited with preventing cell damage linked to the development of degenerative conditions such as coronary artery disease; atherosclerosis; cataracts; Alzheimer’s, Lou Gehrig’s, and Parkinson’s diseases; and cancers. Antioxidants may promote immune system function, especially in elderly individuals, and retard the aging process. Antioxidants may reduce the susceptibility of undesirable low density lipoprotein (LDL) cholesterol to oxidation,which leads to plaque formation in the arteries. Antioxidants help prevent damage to the DNA in sperm, and thus prevent birth defects and childhood cancers.

These favorable features of antioxidants have led to consumer interest in finding ways to increase dietary levels of them, and for food processors to fortify foods with them.

Dietary antioxidants differ one from another, and their functions differ under various circumstances. They are not interchangeable because their mechanisms differ. As illustration, beta carotene, an antioxidant in carrots, does not act the same way as vitamin C, an antioxidant in oranges. However, some antioxidants work in tandem. Examples are vitamin E and selenium. Different antioxidants affect different sites. For instance, beta carotene protects against lung cancer; and vitamin C, against stomach cancer.

Antioxidants combat the harmful effects of oxidation in the body, by blocking the free radical chain reactions that result in cell damage. Free radicals result from normal metabolic processes in which oxygen molecules lose electrons. This creates unstable molecules (the free radicals) that cause oxidative stress. The free radicals attack the body’s healthy cells by attempting to find other electrons to stabilize them. This process causes damage to healthy cells unless they are protected by antioxidants.

Currently, Recommended Dietary Allowances have been established for only three antioxidants: vitamins C and E, and selenium. A recent report by the Panel of Dietary Antioxidants and Related Compounds, released jointly by The Institute of Medicine (IOM) and the National Academy of Sciences (NAS), reviewed food components that demonstrate antioxidant effects, in order to establish levels for Dietary Reference Intake (DRI). Vitamin C and E, and selenium are being considered, and carotenoids have been added. These are considered “The Big Four.”

Vitamin C scavenges reactive oxygen and nitrogen species (both free radicals) and is very powerful in attacking substances that cause inflammation. Also, vitamin C helps in reacting with other antioxidants such as vitamin E and selenium, and regenerates them back into their natural antioxidant forms.

Vitamin E may delay Alzheimer’s disease, and protect against cancer. In diabetes, the increased oxidative stress may be related to a person’s underlying metabolic abnormalities, and be relieved by the antioxidant quality of vitamin E.

Selenium increases the protective effects of vitamin E. Among its antioxidant effects, it may protect against advanced prostate cancer.

Beta carotene, from a family of carotenoids, acts as a scavenger against free radicals, and quenches singlet oxygen (a free radical).

Numerous other antioxidants exist in basic foods. Among them are lutein and zeaxanthin. Their molecular structure is similar to beta carotene. At high concentrations, zeaxanthin is an oxygen quencher. Both lutein and zeaxanthin are found in high concentrations in the lens and retina of the eye, as well as in the liver and kidney. An abundant intake of foods containing these two antioxidants has been associated with lower levels of eye disease and lung cancer.

Lycopenes, common in tomatoes, are the most efficient carotenoid quenchers of singlet oxygen. Polyphenols, found in most fruits and vegetables, show antioxidant behavior in tests. Lipoic acid, essential for energy metabolism, permeates cells readily, and may be an antioxidant. Combined with vitamin E, it enhances the antioxidant effect. Lipoic acid is present in spinach and in meat.

Natural antioxidants have been identified in a variety of foods, including many fruits and vegetables; grains; garlic; honey; tea leaves; and coffee and cocoa beans. Also, they have been identified in many plants, such as burdock root, milk thistle, and ginkgo (Ginkgo biloba).

Herbs and spices contain antioxidants. Many food processors now substitute essential oils from rosemary, oregano, and thyme for the formerly used synthetic antioxidants, to keep fat-containing foods from turning rancid. These substances have antimicrobial as well as antioxidant qualities, which may account for their effectiveness in preserving perishable meats in past centuries. Currently, some food processors use vitamin C and E to help keep meats fresh.

The report from the IOM/NAS panel proposed a definition for dietary antioxidants, in order to characterize the properties of these compounds. The panel decided on three criteria: an antioxidant must be found in the human diet; data on the food component must exist in measurable quantities in reliable food consumption databases; and the substance must demonstrate that it decreases the adverse events of free radicals in humans.

Much information is still lacking in identifying naturally occurring antioxidants in foods and their functions. This work will continue to evolve, and reinforce the truth that basic foods offer health benefits, not only from nutrients, but also from other constituents that we have only begun to acknowledge and investigate.

YOU ASKED FOR IT: QUESTIONS AND ANSWERS

Q. What fruits and vegetables show the most antioxidant activity?

A. Antioxidant activity is measured in Oxygen Radical Absorbance Capacity (ORAC) in test tube experiments. ORAC is a measurement of the ability of foods to subdue oxygen free radicals. Combinations of nutrients in foods have greater protective than single ones.

The highest ORAC in fruits (in descending order) are prunes, raisins, blueberries, blackberries, strawberries, and raspberries. Lower ORAC levels, but still beneficial are in plums, oranges, red grapes, and cherries. For vegetables, kale and spinach top the list, followed, in descending order, by Brussels sprouts, alfalfa sprouts, broccoli florets, beets, red bell peppers, onions, corn, and eggplant.

The author, Beatrice Trum Hunter, MA, has written more than 30 books on food and environmental issues, frequently before widespread public awareness. She was food editor of Consumer’s Research Magazine for more than two decades. She is an honorary member of The Price Pottenger Nutrition Foundation, as well as an honorary fellow of The International Academy of Preventative Medicine and an honorary member of The American Academy of Environmental Medicine. She has been the recipient of many awards, including The Jonathan Forman Award of The Society for Clinical Ecology, The New Hampshire Society for Preventative Dentistry, and The Donnon Pepper Humanitarian Award. She can be reached at 243 Falls Road, Deering, N.H. 03244

CHAGA MUSHROOM ( above) has been found to have one of the highest ORAC values  and can be bought in bulk at Mountain Rose Herbs Below. I make a tea out of Chaga mushroom but I like to call it a coffee because with milk and honey it is a close match. Chaga has a flavor somewhat reminiscent of vanilla. I think its delicious. The same pieces of chaga can be reused  several times. It has many health benefits. Check it out under Bulk Herbs and Spices. If you live in North America…in the northern regions, you may want to forage for it. It grows on birch trees. I found some in the wild in Vermont and was very excited about that.