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Scientists have long known that unhealthy eating habits can be a cause of cancer. But can certain foods taken in the right amounts help prevent cancer?
Evidence of lower cancer rates in countries with eating habits markedly different from the United States indicates they can. Two foods in particular, tea and olive oil, appear to be especially promising for their preventive properties in colon and lung cancer, respectively.
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“Consumption of green tea (black tea is the type most commonly consumed in the United States) reduces the risk for several cancers, including those of the lung, stomach, and pancreas, and recently has been shown to have an association with the reduced risk for colon cancer,” said Theresa Smith.
The assistant professor of pharmacy at USC is in the third year of a five-year, $1.2 million research project funded by the National Institutes of Health to examine whether both green and black tea are able to prevent colon cancer.
She is collaborating on the study with Michael J. Wargovich, a professor of pathology at the USC School of Medicine who also serves as director of basic research at the S.C Cancer Center.
“We’re looking at lab animals that spontaneously get colon tumors and are looking to see if giving them tea will decrease the tumors and how it does that,” said Smith.
Of particular interest to Smith and Wargovich are the role of polyphenols in green and black tea, chemical compounds that inhibit cancer by several mechanisms, such as their antioxidant activity or by altering certain enzymes in the body that might be involved in activating carcinogens.
Evidence of a decrease in lung cancer rates in countries where there is a high level of olive oil consumption, even where the rate of smoking is the same as in the United States, also has led Smith to conduct preliminary research on the role of olive oil as an anti-cancer substance.
That research is in the preliminary stages to obtain enough data to submit a grant to the National Institutes of Health in October.
With further study, Smith hopes to identify biochemical mechanisms by which dietary fat affects lung tumor growth, and whether the risk of lung cancer could be decreased or increased by high intakes of fat in the form of either olive oil or corn oil.
The findings will be useful in planning future epidemiological studies and in the design of strategies for the prevention of lung cancer, Smith said.
Smith and Wargovich’s research is one of numerous studies of a large variety of foods by researchers the world over that will shed light on other potential cancer preventives, from isothiocyanates found in cabbage, broccoli, and other dark green leafy vegetables, to garlic, hot peppers (capsaicin), and curry (curcumin), Smith said.
Eventually the findings will result in more dietary recommendations. In the meantime, Smith recommends eating a variety of foods in moderation and not going overboard on any particular type of food, even if it is touted for its anti-cancer properties.
“This research in general is about the ability to change your health just by altering your diet,” Smith said. “Everyone can do this by looking at what they eat and, from an early age, teaching children what kinds of foods they should eat. I’m more interested in the preventive aspect of cancer than in treatment. Changing our diet is something all of us can do to realize that.”
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Michael Wargovich, pathology, USC School of Medicine, and Theresa Smith, pharmacy, are researching tea to highlight its beneficial properties.
