BUYING NATURAL ANTIOXIDANTS
BUYING NATURAL ANTIOXIDANTS
By now, most of us know about antioxidants, protective chemicals such as beta carotene, and vitamins C and E. During the past decade, these star nutrients have been charged with the ability to protect our health by arresting the production of free radicals. Specifically, antioxidants "work by allowing themselves to be attacked and damaged by free radicals, sparing the cell itself," explains Neal Barnard, MD, in Food for Life (Harmony Books, 1993).
Left unchecked, free radicals can rob our health by "rusting" our cells. Over time, this can leave us vulnerable to a plethora of health problems. Indeed, excess free radical production has been linked with more than 50 ailments, ranging from premature aging and clogged arteries (atherosclerosis) to cataracts and cancer.
Putting a break on the health-robbing abilities of free radicals isn't always easy-after all, they're a natural by-product of breathing, as well as our external environment. But if you know which antioxidants to consume, how much, and how often-based on your own personal lifestyle-you can begin to outsmart these outlaws.
ACE Antioxidants
Pioneering antioxidant and exercise researcher Kenneth Cooper, MD, MPH, calls antioxidants a "police force" that can reduce free radical production. The most important, he believes, are "exogenous (outside) antioxidants," especially vitamin C, vitamin E, and beta carotene.
At the Cooper Aerobics Center in Dallas, Texas, Dr. Cooper and his associates support an antioxidant-rich diet-especially abundant in fruits and vegetables, but also whole grains, legumes (beans and peas), and nuts and seeds. Says Ted Mitchell, MD, medical director for the Cooper Wellness Program: "The fact of the matter is, we form free radicals literally thousands of times every day. What we're hoping to do with antioxidants-whether through diet, which is the preferred way, or through vitamin supplements-is to reduce [the harmful] effects somewhat." He adds: "It's important to understand, though, that people in this field are feeling their way" [to optimal doses].
Supplements or no supplements? This is the question that lies at the core of the antioxidant debate. While most health care professionals recommend obtaining antioxidants from the foods we eat, only about 10 percent of Americans eat the recommended five or more servings of antioxidant-rich fruits and vegetables daily. "If you work at accenting fruits and vegetables in your diet," says Dr. Mitchell, "you can get enough beta carotene and vitamin C. But it's harder to get an adequate intake of vitamin E." Found in high quantities in nuts, seeds, and plant oils, "by the time you get enough to have sufficient antioxidant properties, it's likely you've overrun your calorie and fat count for the day."
Perhaps to compensate for our typically low intake of fruits and vegetables-and ensuing low antioxidant levels-many Americans have turned to supplements. Indeed, current reports indicate we spend $1.5 billion annually on vitamin, mineral, and herbal supplements. Vitamin C supplements remain the best-seller, but lately vitamin E has been gaining on C as our most popular antioxidant vitamin tablet or capsule.
Is obtaining antioxidants through vitamin supplementation both safe and effective? Yes and no-depending on which research you review. Some scientists do not recommend supplementation, and others embrace it as smart health "insurance," while a third camp takes still another approach, believing the ideal is to combine a health-smart diet together with moderate amounts of antioxidant supplements to enhance health.
Vitamin C Revived
Vitamin C is currently America's most popular antioxidant supplement. Millions of us take daily doses well above the recommended daily allowance (RDA) of 60 mg-with no known side effects (probably because the body eliminates excesses). Indeed, research has shown doses between one to six grams a day may lessen both the symptoms-and duration-of colds (Journal of the American College of Nutrition, 1995). (This study "overturns" two decades of research that disputed two-time Nobel-Laureate Linus Pauling's claim that megadoses of C are safe and can reduce the symptoms of colds.)
Beta Carotene Blues
Of the three major antioxidants, it is perhaps beta carotene that has received the most critical media attention. Concerns first surfaced in 1994, when a six-year-long research project from Finland linked supplemental beta carotene taken by cigarette smokers to a higher risk of lung cancer.
Then earlier this year, the National Cancer Institute (NCI) developed similar concerns about beta carotene supplementation. Like the Finnish study, the NCI's Beta Carotene and Retinol Efficacy Trial (CARET) was designed to explore the influence of beta carotene (and vitamin A) as preventive agents for lung cancer in high-risk men and women (i.e., heavy smokers and asbestos workers). But four years into the study, investigators terminated the study, believing the beta carotene supplements may actually be doing harm. Another NCI study, the 12-year Physician's Health Study (PHS), which examined 22,000, mostly non-smoking, male physicians who were taking beta carotene every other day, showed neither benefit nor harm from beta carotene supplementation.
In response to this inconclusive research, the National Institutes of Health (NIH) eliminated beta carotene supplements from its ongoing 10-year Women's Health Initiative research project-a clinical trial of 40,000 female health professionals designed to measure the impact of dietary changes on breast cancer, colorectal cancer, and coronary heart disease. However, the study will continue to evaluate every-other-day doses of 600 IUs (international units) of vitamin E (and 100 mg of aspirin or placebos).
Although the results of these studies provide no conclusive evidence of harm-or benefit from beta carotene supplements-until we know more, the NCI and other national organizations, such as the American Heart Association (AHA), are urging us to get our antioxidants only from the foods we eat, while others are modifying their beta carotene recommendations (see "Antioxidant Rx" page 46). "The epidemiological studies have shown that populations that consume higher levels of plant foods-fruits, vegetables, and grain products-have a reduced risk of several types of cancer," offers Carolyn Clifford, PhD, chief of NCI's Diet and Cancer Branch. Andrew Nicholson, MD, director of preventive medicine at the Physicians' Committee for Responsible Medicine, also believes the goal is for people to eat a healthful, plant-based diet, rich in fruits and vegetables; supplements should not substitute for a healthy diet.
Says Dr. Mitchell: "Although the Finnish and NCI studies were well-designed, they were done with skewed populations [that included smokers and perhaps others with an unhealthy lifestyle]. Results from ongoing quality studies are needed before we can draw conclusions for non-smokers. Unfortunately, we're not going to have information about these results for another five or 10 years."
Health-Smart Strategies
Given the inconclusive state of antioxidant research, what steps can a health-conscious person take to pursue optimal health with antioxidants? First, because most of us are not meeting the "five-a-day" NCI recommendation for including antioxidant-loaded fruits and vegetables in our diet, you may want to consider a sensible intake of supplements, keeping in mind the key concept: strive to obtain your "ACE" antioxidants from food. With its cornucopia of balanced nutrients (e.g., vitamins, minerals, fiber, etc.) and health-enhancing substances (e.g., phytochemicals, enzymes, etc.), antioxidant-rich foods remain your first-and best-line of defense against disease.
To begin, consider taking the guesswork out of the ideal doses for yourself by doing your own "research." Speak with your physician, who along with diagnosing any ailments (such as liver problems or elevated iron stores) that may influence how much supplementation would be best for you, he or she may opt to offer a screening test to find out if you are consuming enough antioxidants, particularly vitamin E.
To date, few physicians and laboratories offer such a test, but it is available. The Cooper Center, for instance, offers it to patients, and it is also available through Antibody Assay Laboratories (AAL), located in Santa Ana, California. Called the Oxidative Protection Screen™, AAL's test helps your doctor determine if you are producing an excess of free radicals, as well as how effectively your body protects itself (oxidative protection) against free radical damage.
Future Focus
What does the future of antioxidants hold? Perhaps the future already has arrived. For instance, food preservatives such as BHA, BHT, ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), and lecithin, are just some food additives with antioxidant properties that food manufacturers have been adding to our food for decades to keep food from spoiling (oxidizing). A caveat, though, is that we don't yet know if the quantity and type of antioxidants added to preserve food have beneficial effects once they're consumed. However, if further research continues to make a stronger case for antioxidant intake, you might see food fortified with amounts higher than the RDA in the not-too-distant future.
In addition, researchers who have explored beyond the beta carotene and vitamins C and E horizon have isolated polyphenols, the antioxidant component in green tea. These naturally occurring chemical compounds appear to have the potential to inhibit tumor growth in animals, as well as lower the risk of cancer of the esophagus.
To date, most research on the health benefits of antioxidants has focused on vitamin E. Indeed, adequate amounts have been charged with the ability to reduce heart disease (Annals of Internal Medicine, December 1, 1995) and increase the immune response, which, in turn, may provide protection against cancer and infectious diseases (Lancet, January 21, 1995).
To unravel the beta carotene confusion, another major research trial, called the Women's Antioxidant and Cardiovascular Study (WACS), is continuing regardless of the spate of negative findings about beta carotene. With no negative findings to date, the WACS will evaluate the effects of vitamins E, C, and beta carotene on 8,000 women at risk for heart disease; so far the results seem promising.
However, as concern mounts about safe and effective amounts of beta carotene to recommend, more and more, researchers are focusing their microscopes on carotenoids, a family of more than 600 natural substances in plants (one of which is beta carotene) that contains a multitude of antioxidants and other health-enhancing substances. "In studies, foods that provide carotenoids ... show up time and again as promoters of good health," says the UC Berkeley Wellness Letter. "It's time to rethink this issue" (April 1996).
Although the medical community has not reached a consensus about antioxidant supplementation, many well-respected scientific experts believe there is a place for supplemental antioxidants. There is also a consensus that supplements are not a substitute for a healthy diet.
Alliance for Aging Research (AAR): The Alliance is the first national non profit health organization to issue specific public health guidelines on obtaining antioxidants from diet and supplements, based on findings from more than 200 clinical and epidemiologic studies on antioxidants conducted over the past two decades. Their conclusion: First, strive to obtain antioxidants by eating a diet rich in fruits and vegetables.
Supplementation: AAR suggests that people at high risk for cancer, especially asbestos workers and smokers, should not take any beta carotene supplements. For others interested in health promotion and disease prevention, they recommend the following ranges of supplements (in an aging population): vitamin C, 250 to 1000 mg daily; vitamin E, 100 to 400 IUs daily; beta carotene, 17,000 to 50,000 IUs (10 to 30 mg) daily.
UC Berkeley: The UC Berkeley Wellness Letter, with an editorial board that includes some of the top nutrition researchers in the country, supports supplementation "to hedge your bets." But in light of the NCI's findings, they have withdrawn their recommendation for smokers to take beta carotene supplements-though they see no harm or benefit for non-smokers to take low doses if it's not obtained in the diet. Their recommendation: In addition to eating five or more servings of fruits and vegetables daily, 200 to 800 IUs (133 to 533 mg) of vitamin E daily; 250 to 500 mg of vitamin C, but no more than six to 16 mg beta carotene daily for non-smokers not obtaining adequate amounts in their diet (April 1996).
Ornish Institute: Dr. Dean Ornish's Preventive Medicine Research Institute (PMRI) conducts pioneering research on lifestyle (diet, exercise, stress management, and group support) and "reversing" heart disease. Says PMRI's research director, Larry Scherwitz, PhD, "If a three-day nutritional analysis reveals program participants are not obtaining adequate antioxidant levels in the diet, we recommend a range of supplement doses": one to three grams vitamin C; 100 to 400 IUs of dry vitamin E daily; 10,000 to 25,000 IUs of beta carotene. Interpretation: If your dietary intake of antioxidants is low, choose supplement doses at the high end of the recommendation; if your dietary intake is adequate but not optimal, chose supplement doses at the lower end. As "insurance," PMRI suggests taking a multi-vitamin, without iron, each day.
Cooper Center: The Kenneth Cooper Aerobics Center also espouses antioxidant supplementation-as an adjunct to consuming five or more servings of fruits and vegetables daily. "After assessing someone's nutritional intake, we make recommendations," says Dr. Mitchell. If the analysis shows adequate daily intake, defined as 1000 mg vitamin C, 15 mg (25,000 IUs) beta carotene, and 400 IUs vitamin E (specifically d-alpha tocopherol-the natural form of vitamin E), then extra supplements aren't recommended. "But if the intake is below the recommended amounts [to combat free radicals], we now know how much extra each person needs to take each day to meet our 'template'."
(Note: Although there is no hard research evidence [yet] that endurance athletes benefit from higher doses of antioxidants, the Center suggests that anyone exercising more than five hours weekly should double the recommended dosage to combat excess free radical by-products.)
Written by: Deborah Kesten
RELATED LINKS:
|
|---|
| * * * COMPANIES & PRODUCTS * * * |
|---|
| * * * IN-HOUSE RESOURCES * * * |
|---|