Saturday, July 19, 2008

Antioxidants: Protection from cancer-causing free-radicals with antioxidants contained in vitamin C, Pycnogenol and various herbs (Part II)

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. "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).

Assessing Antioxidants

Though the antioxidant vitamins A and C are abundant in vegetables and fruits, less than 10 percent of Americans consume the five-plus servings of fruits and vegetables each day needed to get enough of these nutrients. And our intake of vitamin E-rich grains, nuts, and seeds isn't much better. For instance, almost 50 percent of women between 19 to 50 consume less than 70 percent of the recommended amount.

If we did have the time to focus on our antioxidant intake, what would be the "best" dose for enhancing health? The figures are still being debated (see "Antioxidant Rx" page 46), but the government suggests this minimum recommended daily allowance (RDA): 5,000 IUs for vitamin A; 60 mg for vitamin C, and between 12-15 IUs for vitamin E. To give you a perspective about what this means in "real life," one medium orange meets the vitamin C requirement, and a medium carrot far exceeds the vitamin A recommendation. For most of us, this means that munching on just a few colored fruits and vegetables throughout the day could pay big dividends in terms of antioxidant intake.

Vitamin E intake, though, is more challenging, because meeting the RDA for vitamin E usually means consuming lots of nuts, seeds, and oils. But if you do, it's likely you also would far exceed the daily fat allotment that is safe and beneficial for your health (and waistline). The "fat-overload" problem is further exacerbated if your goal is to consume levels of vitamin E that surpass the RDA (perhaps as high as 400 IUs), which many experts recommend in order to lower the odds of health problems ranging from heart disease and cataracts to some kinds of cancer.

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