New findings by a Queen's University research team dispel the popular notion that eating so-called "natural" foods will protect against cancer.
In fact, certain types of common foods and alcoholic beverages such as wine, cheese, yogurt and bread contain trace amounts of carcinogens. Maintaining a balanced diet from a variety of sources -- including garlic -- is a better choice, the researchers suggest.
Led by Dr. Poh-Gek Forkert of Queen's Department of Anatomy and Cell Biology, the team has discovered that a naturally-occurring carcinogen found in alcoholic beverages and fermented foods causes DNA modification and mutations, ultimately leading to abnormal cell growth and lung cancer. Her research also shows that a component of garlic significantly reduces these changes.
The most recent Queen's findings are published on-line today in the journal, Carcinogenesis. This is the third in a series of four related papers: two of the companion papers are published on-line in the International Journal of Cancer and Drug Metabolism and Disposition.
Dr. Forkert's team includes PhD student Lya Hernandez and postdoctoral fellows, Drs. Heidi Chen and Ashish Sharma (all from Anatomy and Cell Biology). Also collaborating on the team are PhD student Martin Kaufmann (Biochemistry), Dr. Glenville Jones (Biochemistry), and Dr. Raymond Bowers (Chemistry).
The researchers are studying the effects of treatment with vinyl carbamate in mice. This substance is derived from ethyl carbamate (urethane), a by-product of fermentation found in alcoholic beverages, and fermented foods like cheese, yogurt and bread. It is also present naturally in tobacco.
Now labeled as a potential human carcinogen by both the World Health Organization and the International Agency for Research on Cancer, urethane was given inadvertently to millions of patients in Japan, between 1950 and 1975, in analgesic and sedative drugs. It was estimated that the total dose of urethane administered to a 60-kilogram patient was about 0.6 to 3.0 grams. This is believed to be the largest dose on record of a pure carcinogen administered directly to people.
In 1985, Health and Welfare Canada placed limits on urethane contained in Canadian (but not imported) alcoholic beverages. "The problem is how to regulate the levels in imported goods," says Dr. Forkert.
In these studies, the mice were administered a single high dose of the carcinogenic chemical. Human exposure differs from that in mice in that it is much lower, and occurs over a prolonged period of time. A question has been raised regarding the effect on people who ingest low levels of the chemical daily over many years, and perhaps over a lifetime.
"We believe that people should not be apprehensive about consuming these foods and beverages: if consumed at low levels, they probably don't pose a risk. It might be prudent, however, to have a varied diet and to limit drinking certain alcoholic beverages," says Dr. Forkert. "And include garlic!" she adds.
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