Supplements du Jour: Antioxidants
Never regret growing old; it is a privilege denied many.
Healthy Diets Revisited
Thanks to wisdom expressed in the cliché-laden dialect "Healthspeak," we all know the importance of lots of sleep, reduced stress, plenty of exercise, flossing, yearly checkups, and cancer screening. But towering above all these promised components of a long, healthy life, stands first and foremost, a "good diet," however one may define it.
The public and the professions are increasingly seduced by thousands of contradictory pronouncements provided by Government, scientists, marketing hucksters, and ambitions amateurs all of whom provide us with an indigestible mixture of "truth," lies, and mythology, driving our food perceptions and nutritional orthodoxies. So let the games begin, because most of us are true believers in what constitutes a "healthy diet," and know the deadly perils of "wrong" foods, including saturated fats one year, trans fats the next, and simple sugars the next. Moreover, we all agree the right diet is the final common pathway to long life despite Mother Nature's cruel decree that longevity more often than not is disfigured by disease, disability, and dementia.
What Are Antioxidants?
Oxidation reactions are critical for life, but they can also be damaging. Plants and animals maintain complex protective systems of multiple types of antioxidants, such as vitamins C, E, beta carotene, as well as various enzymes and their components, such as the mineral selenium. Present theory holds that antioxidants can be compromised and lose their protective value against cell damage by vulnerability to unstable molecules known as free radicals. Because oxidative stress has been invoked in the pathogenesis of many human diseases, the use of antioxidants has been intensively studied, particularly in neurologic and some malignant diseases. However, it is unknown whether oxidative stress is the cause or the consequence of such diseases. Vitamins were always heralded as nature's own powerful antidote against chronic illness, and degenerative disease. In recent years, a constellation of studies have concluded that people who consumed large amounts of the antioxidants vitamins C and E, beta carotene and selenium were often healthier than those who ingested comparatively little of these substances. Yet antioxidants are abundant in a wide variety of fruits and vegetables, as well as nuts, grains and some meats, poultry and fish. In foods containing tomatoes, look for a red relative of carotene or vitamin A, the famous lycopene adorning the labels.
Antioxidants: the Miracle Supplements
The search term "antioxidant" gets you 10.6 million hits on Google. Despite the widespread availability of antioxidants in normal diets, as a result of extensive, clinical, animal, and test tube studies, these compounds have become widely and uncritically used as ingredients in dietary supplements with the implication they prevent diseases such as cancer and coronary disease. Almost overnight millions of consumers became antioxidant worshipers, and morphed into enthusiastic pill poppers while antioxidants were added to an astounding variety of foods.
Although some studies have suggested antioxidant supplements have health benefits, other large clinical trials did not detect any benefit from the formulations tested, and some studies found excess supplementation may occasionally be harmful. In recent years, large-scale, randomized clinical trials reached inconsistent conclusions. Five large-scale clinical trials published in the 1990s reached differing conclusions about the effect of antioxidants on cancer. A 1994 cancer prevention study demonstrated that lung cancer rates of Finnish male smokers increased significantly with beta-carotene and were not affected by vitamin E, a finding at variance with the results of a large Chinese trial. Another 1994 study also demonstrated a possible increase in lung cancer associated with antioxidants. The 1996 Physicians' Health Study (PHS I) found no change in cancer rates associated with beta-carotene and aspirin taken by U.S. male physicians.
Last but not Least
In a study published Feb.28, 2007 in JAMA, researchers in Europe analyzed data from 68 large trials in which more than 232,000 adults were given antioxidant supplements. In a subset of those studies, the scientists concluded, subjects taking vitamins A and E and beta carotene saw a slightly increased risk of death compared with those who did not take supplements. (Vitamin C had no effect on mortality, the team found.) Final Conclusions: "Treatment with beta carotene, vitamin A, and vitamin E may increase mortality. The potential roles for vitamin C and selenium on mortality need further study."
Has America's love affair with antioxidants proved dangerous for our health? Not likely, other experts say. Is it begging the question to add, as did Meir Stampfer, an epidemiologist at Harvard, "A lot of researchers, including myself, were quite disappointed that the trials showed no benefit, particularly for vitamin E.? But I don't think it closes the door on the antioxidant concept."
Unsurprisingly, the JAMA study evoked some frightening headlines and vigorous criticism. Dr. Stampfer and others say its analysis is flawed, because among other reasons, it excludes data from hundreds of other studies, and does not detail the causes of increased mortality among supplement users. Dr. Andrew Shao, vice president of the Council for Responsible Nutrition, a trade group for the supplement industry, said, "Most of these patients already had disease, so the conclusions simply aren't relevant to a healthy population." Yet other studies of healthy adults taking antioxidants have also proved disappointing. After tracking nearly 40,000 women for a decade, researchers at Harvard found that those taking vitamin E were just as likely as others to suffer cardiovascular disease and cancer.
"There still may be subsets of people who are very responsive to the benefits of antioxidants," said Dr. Jeffrey Blumberg, a nutrition professor at Tufts who serves on scientific advisory boards for some supplement companies. See this excellent article in the New York Times by Michael Mason March 13, 2007.
Should We Take Antioxidants?
Perhaps it's time for us to give up the fantasy that high dose supplements, including, but not limited to antioxidants, will provide us with a magic bullet against disease. A diet with ample fruits and vegetables contains thousands of antioxidants. There seems to be little evidence that taking antioxidants as food supplements or in their naked pill form will do anything to promote our health or longevity. Indeed, in excessive amounts they may even be harmful.
Martin F. Sturman, MD, FACP
Copyright 2006, Mathemedics, Inc.
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