According to Ames, cancer incidence is mostly related to age because each day, the DNA in each cell is damaged up to 10,000 times. Our cells have mechanisms to repair DNA damage but these mechanism are imperfect because a majority of our bodies’ resources are devoted to reproduction and not to maintenance. Thus, the number of un-repaired and nutated DNA increases with time and is thought to contribute to the incidence of cancer and other age-related illness.
Synthetic pesticides, according to Ames, represent little cancer risk to humans. Plants, unlike animals, are immobile and do not have the ability to flee a threat to their survival. Therefore, plants are chemical factories that produce many natural pesticides that protect them from fungi, insects and predators. Ames estimated the 99.99% of the total pesticides that we ingest are natural and only .01% are synthetic. Thus, too much of our nation’s resources are used in regulating pesticides and other synthetic chemicals relative to the risks they pose in causing cancer. The average daily intake of DDT, a banned insecticide that has saved millions of lives around the world by killing insect vectors that spread diseases such as malaria, has the same carcinogenic risk as drinking one can of beer (a substance containing natural carcinogens) every 8000 years.
Fruits and vegetables contain many chemicals that are effective in reducing the risk of cancer to humans. For example, the chemicals that make carrots orange (carotenoids) are antioxidants and protect plants for excess energy the plant receives from the sunlight. Carotenoids, as antioxidants, reduce the amount of oxidation and damage to our DNA, thus protecting us from cancer. In a study in Japan, smokers who increased their dietary intake of vegetables reduced their risk of cancer by 50%.
The take home message from Bruce Ames’ lecture - if you want to reduce your risk of cancer, quit smoking, eat less fat and eat your five servings of fruits and vegetable every day - just like your mother told you!
Bruce Ames, a nationally prominent professor of biochemistry at the University of California at Berkeley, lectured the following about the relationship between cancer, aging and the environment.
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