Index - Click to move to a section
Cancer is one of the world's number one killers; nearly 75% of all Americans
are affected by this disease. Thus, much time and research has been put
into finding a preventative means of slowing the deaths attributed to this
disease. Research by the scientific community coupled with propaganda from
the media has brought antioxidants to the forefront in preventative medicine
against cancer. This site will discuss what the claims are about antioxidant
vitamins and what science has shown to in fact be true. This site is simply
a summary; a beginner's guide to an ever-changing world of antioxidant
Antioxidants work in protecting your body from cancer by reducing the effects that oxygen free radicals have on cell damage. This oxidative stress has both internal (digestion of certain nutrients, fighting off bacteria, etc.) and external or environmental causes. The oxygen free radicals are atoms or groups of atoms with unpaired electrons formed between the interaction of oxygen and certain molecules. These radicals immediately attach themselves to other cells in order to balance out the number of electrons and become stable. Once formed, these free radicals can have a very destructive impact on a cell. Those radicals which do not cause death to the cell can stimulate the growth of cancer when they interact with and cause damage to the DNA within the cell. Scientific evidence suggests that these oxygen free radicals play important roles in the expansion of tumors and the acquisition of malignant properties. (Role of Oxygen Free Radicals European Journal of Cancer. 32A(1):30-8, 1996 Jan.)
To prevent this free radical damage, the body utilizes a defense system made up of antioxidants. The antioxidant molecules interact with the oxygen free radicals and halt the spread of cancer causing cells with damaged DNA before other vital molecules are damaged. The main micronutrient antioxidants are vitamin E, beta-carotene, and vitamin C. Additionally, a trace metal known as selenium is required for the proper functioning of one of the body's antioxidant enzyme systems. Since the body cannot produce these micronutrients itself, they must be ingested through the diet. (http://www.liberty.com/home/appaloosa/protx.html)
Vitamin E: Vitamin which helps protect our bodies when they are exposed to environmental pollutants that interfere with healthy oxygen metabolism. It is a fat soluble vitamin found in nuts, seeds, vegetable and fish oils, whole grains, fortified cereals, and apricots. The recommended daily allowance (RDA) is 15 IU per day for men and 12 IU per day for women.
Vitamin C: Ascorbic acid is a water soluble vitamin found in citrus fruits, peppers, cabbage, spinach, broccoli, most melons, kiwi, and strawberries. The RDA is 60mg per day.
Beta-carotene: Converted to vitamin A by the body. Found in liver, milk, spinach, carrots, squash, broccoli, yams, cantaloupe, peaches and grain.
-"Even the RDA is far short of what you need to stay healthy, indicating only the amount of a nutrient you need to keep from getting diseased. The amounts of nutrients you need for vibrant good health and energy are much higher than the RDA!" ....."antioxidants do everything from preventing heart disease and cancer to improving vision and enhancing brain function"
Ads like these are found all over the Internet, and they all seem
like a little much to me. Remember, these people are trying to sell products,
thus they offer us the "prevention to cancer" or a fountain of
youth found magically in their tiny little capsule which they invented
and stand to make a nice profit from. As you will soon find out, scientific
evidence proves that supplements are not needed and can, in fact, be detrimental
in the prevention of cancer.
Scientific research is somewhat cloudy in this area, but most would lean toward no. A study done by the University of Leeds School of Medicine states that there is little evidence that vitamins of any type are able to greatly modify the progression of established malignancy. In contrast, they found considerable laboratory evidence from chemical, cell culture and animal studies that antioxidant vitamins and related micronutrients were able to slow, or possibly prevent the carcinogenic process. These antioxidant vitamins came from foods, however, not supplements. This suggests that something else in the food may aid in the effectiveness of the antioxidants. (Micronutrients, antioxidants and risk of cancer. Bibliotheca Nutritio et Dieta. (52):92-107, 1995.)
There is no doubt that antioxidants are a necessary and important
component for the prevention of cancer, but nobody knows if supplements
should be taken and, if so, how much. Results have come forth from an experiment
sponsored by the National Cancer Institute that increased interactions
of the body and antioxidants can cause potential toxicity in the body and
an increased risk of cancer. The April 14, 1994 issue of the "New
England Journal of Medicine" reported the findings of a prevention
trial conducted in Finland. The results showed that vitamin E and beta-carotene
supplements, when taken by male smokers age 49 and older, did not protect
against cancer. This study marks the best chance of being able to identify
a genuine beneficial effect of antioxidant vitamins on incidence of cancer
because it is a large (29000 males) and well-designed randomized trial.
The primary conclusion of the study showed that there was little evidence
of a beneficial effect of supplemental vitamin E or beta-carotene in prevention
of lung cancer over the six years of the trial. Instead, the group consuming
the supplemental beta-carotene had a significantly higher (18%) incidence
of lung cancer than those participants who did not take it. Furthermore,
they had higher rates of cancers of the prostate and stomach along with
a higher death rate (8%). The FDA agrees with the study's authors that
the results "raise the possibility that these substances may have
harmful as well as beneficial effects." (http://cancer.med.upenn.edu/pdq/600410.html)
The key to remember is the connection between good nutrition and
good health. Sir Richard Doll, MD, D.Sc., and Richard Peto, MD, estimated
that between 20% and 60% of cancer deaths were related to dietary factors--much
of cancer may be preventable! Epidemiological observations show lower cancer
rates in people whose diets are high in fruits and vegetables. These foods
are plentiful sources of vitamins (including those that are natural antioxidants),
minerals, biochemical compounds, and fiber-ingredients that may help to
reduce cancer risk. Additionally, these foods tend to be lower in fat and
calories. Recommendations by the FDA and the National Cancer Institute
emphasize the "Five-a-Day " program. This is a program whereby
an individual eats 5 or more fruits or vegetables along with a low fat
diet. Research clearly shows that this is the best preventative measure
against cancer so far. (http://www.oncolink.upenn.edu/cancer_news/diet_cancer.html)
-Eat a healthy diet full of fruits and vegetables. This will give you all of the antioxidants you need for protection against oxygen free radicals.
-Eat a low fat diet. Many of the fatty foods we eat (processed meat) are filled with nitrites and nitrates which cause an increase in free radicals in the body.
-Be wary of the ads you read about the effects of antioxidants and the need for supplements; stick with the recommendations of the FDA. Little is known about the long term side effects of mega-doses of antioxidants. We do know that it can have a potentially toxic effect coupled with a possible increase in risk of getting cancer. Be careful, don't throw your money away!
1. Role of Oxygen Free Radicals European Journal of Cancer. 32A(1):30-8, 1996 Jan.
6. Micronutrients, antioxidants and risk of cancer. Bibliotheca Nutritio et Dieta. (52):92-107, 1995.
9. New England Journal of Medicine. April 14, 1994
Psychology DepartmentThe Health Psychology Home Page is produced and
maintained by David Schlundt, PhD.
|Return to the Health Psychology Home Page|
comments or questions to Dr. Schlundt
|Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries | Administrative Departments | Medical|