Antioxidant Pros and Cons

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Throughout my daily routine of counseling patients and teaching classes, I often get asked, “Should I take antioxidant supplements to reduce my risk of cancer and heart disease?”

Why antioxidants?
Antioxidants have three team members: minerals, vitamins and phytochemicals. You need all three to neutralize free radicals or oxidants in your body.
Free radicals are undesirable because if they are not squelched by some antioxidant substance they can set off a chain reaction of molecular damage. A simple example is how vegetable oils, nuts and whole grains oxidize and turn rancid over time at room temperature.
In your body, free radicals are generated from all sorts of things, including alcohol consumption, cigarette smoke, pollution and pesticides, to name a few.
Normal cellular activity also generates significant amounts of free radicals but not all are bad. For example, immune cells generate free radicals to kill bacteria infecting the body. Exercise also generates free radicals but is very beneficial to your health.
Free radicals produced by cellular metabolism can be controlled by a variety of enzymes. require one or more minerals such as selenium or copper to neutralize free radicals. Minerals only function as antioxidants when part of enzymes.

Caution Here
With mineral supplements, I emphasize caution. Good guys such as selenium, iron, copper and zinc, can be toxic in doses higher than one would get from eating a well-balanced diet.
Antioxidant vitamins, unlike minerals, work by themselves so taking supplements of these can increase antioxidant capacity; however, more isn’t necessarily better here.
For example, in two well-designed studies, beta-carotene supplements failed to reduce cancer deaths and cancer deaths and the overall death rate actually increased in those taking the supplements.
Most studies show that 200 to 400 I.U. of Vitamin E will reduce deaths from cardiovascular disease but high doses of alpha-tocopherol also appear to increase the risk of hemorrhagic strokes. Animal models clearly demonstrate that lowering LDL (bad cholesterol) is much more important in preventing atherosclerosis than taking Vitamin E supplements. So supplements are no substitution for cutting saturated fat and cholesterol.
Vitamin C supplements above 500 mg. were recently found to increase mutations in DNA which means that high doses of this antioxidant may be more pro-oxidant than antioxidant. Large doses of ascorbic acid were also shown to significantly shorten the lives of guinea pigs. Body tissues become saturated at a daily intake of about 200 mg. and daily doses above 400 mg. have no evident value according to a well-designed study.

Plants Are Beneficial
Lastly, besides vitamins and minerals, you also need antioxidants which are supplied by the body and plants (phytochemicals).
Lutein found in large amounts in spinach appears to reduce free radicals in the eye which lead to cataracts and macular degeneration. Epidemiological studies suggest it may reduce these two major causes of vision loss.
Zeaxanthin (berries) and lycopene (tomatoes) are other powerful antioxidant carotenoids that may help protect the eyes.
At the present time, it is premature to recommend antioxidant supplements for everyone. Too little is known about the risks versus the benefits, especially over a long period of time. Furthermore, a large study found no evidence of increased longevity among vitamin and mineral supplement users in the United States.
Antioxidant supplements may be of some value in reducing the risk of certain diseases in select individuals but are no substitute for a healthy diet. People interested in reducing their risk of heart disease, cancer and other diseases should be advised to eat more fruits, vegetables, whole grains, beans, seeds and nuts.

Jay Kenney, PhD, RD, FACN.

Antioxidant Q&A

Q: What are the best food sources of
antioxidants?

A: Fruits and vegetables are by  far the best. Others include whole grains, beans, nuts, seeds, tea, coffee, red wine, herbs, spices,  garlic and chocolate. Note that it is the cocoa powder in the chocolate that contains the phenols - these are not found in cocoa butter.

Q: How important are antioxidants in the “big picture” of good health?

A: Antioxidants are another important reason to eat a plant based diet containing whole versus processed foods. It is important, however, not to overemphasize any one factor when considering a healthy diet e.g. fat, antioxidants, etc. For example, coconut contains important antioxidants but if you focused on these alone you would overlook the fact that coconut  also contains a fair amount of saturated fat which raises LDL (bad) cholesterol levels.

By J.K.

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