Fish got a boost when the American Heart Association began recommending at least two servings each week to protect against heart disease. This is a good idea for more reasons than one. Fish contain omega-3 fatty acids, fat that seems to provide several health benefits—including lower risk of cancer.

Laura Jenski, PhD, head of biological sciences at Marshall University in West Virginia, has been studying omega-3 fatty acids and their effect on cancer for more than a decade. Early studies explored the effect of different oils—such as fish oil rich in omega-3 fatty acids and corn oil containing omega-6 fatty acids—on tumour growth in mice. The research showed that diets rich in the omega-3s slowed tumour growth.

KILLING CANCER CELLS

Jenski’s recent research involves inserting fatty acids into the surface membranes of cancer cells. They found that omega-3s seemed to cause a change in the body proteins that help the immune system look for abnormal cells. In particular, they boost the effectiveness of the proteins, helping the immune system spot cancer more quickly.

Asked about practical applications of her research, Jenski says, “Scientists are already devising strategies to stimulate the immune system to kill cancer. We might be able to combine such a strategy with the insertion of omega-3 into cancer cells, making them more susceptible to immune attack.”

OMEGA-3 IN CANCER TREATMENT?

Jenski and colleagues have also explored the role of omega-3 in treating cancer. They designed a special phospholipid (fat found in all living cells) that contains an omega-3 fatty acid called DHA, and an anticancer drug, methotrexate. It is put into a microscopic sac that is used to deliver drugs to a cell or tissue. This sac (called a liposome) is different from others being used, says Jenski, because it does not allow the cancer drug to leak out.

“Both the drug and the DHA are delivered to the cancer cell at the same time. We think that the DHA and methotrexate work in different ways to eliminate cancer, and we think together they work synergistically,” Jenski says. “Methotrexate is very toxic and is usually given intravenously. But by delivering it with DHA in a liposome, the body is protected. The methotrexate is released only into the cancer cell, so less of it is needed.”

Fish sources of omega-3 fats include salmon, mackerel, tuna and herring. Fish oil supplements are also convenient and effective.

Reprinted from the American Institute for Cancer Research Newsletter, 72, Summer 2001.