Wednesday July 11 4:04 PM ET

Flaxseed Could Help Slow Prostate Cancer - Study

By Christopher Doering

WASHINGTON (Reuters) - A common fiber supplement called flaxseed could slow the progression of prostate cancer in men when included as part of a low-fat diet, scientists said on Wednesday.

Researchers led by Dr. Wendy Demark-Wahnefried at Duke University said flaxseed contains a fiber compound called lignan that may slow tumor growth by binding to the male hormone testosterone, which is believed to contribute to the progression of prostrate cancer.

Flaxseed also contains omega-3 fatty acids, a potentially healthy fat that has slowed cancer growth in animals.

Demark-Wahnefried and others cautioned that further studies are necessary to determine whether the reduction in cancer growth was caused by the flaxseed, a low fat diet, or a combination of the two elements.

``The results are compelling, but...(it) is premature to tell people to use flaxseed,'' Demark-Wahnefried said in a telephone interview. ``Ultimately we want to see if it (flaxseed) has a role in cancer prevention.''

The study will be published in the July issue of the journal Urology. The findings are being reviewed by the National Cancer Institute (news - web sites), part of the U.S. National Institutes of Health (news - web sites), and the American Cancer Society (news - web sites).

Prostate cancer (news - web sites) is the second most commonly diagnosed form of cancer and the No. 2 cause of cancer death among U.S. men, according to the American Cancer Society. The group estimated that 198,100 new cases of prostate cancer will be diagnosed and 31,500 men will die of it in 2001.

LOWER TUMOR CELL PROLIFERATION RATES

The Duke study involved 25 cancer patients who were awaiting the removal of their prostrate. Each member of the trial group consumed each day three tablespoons of ground flaxseed mixed into cereal, yogurt, applesauce or juice.

Demark-Wahnefried found that men who were on a low-fat, flaxseed-supplemented diet for an average of 34 days experienced decreased levels of testosterone, lower tumor cell proliferation rates and higher levels of cancer cell death.

The researchers compared the results to tissue samples taken from other patients who had prostate cancer but did not consume flaxseed or follow a low-fat diet.

Patients with less advanced prostate cancer reported a greater decrease in a key marker of cancer growth, the study showed.

Flaxseed is a common form of grain that recently has grown in popularity because of its potential to reduce the risk of cardiovascular disease and cancer.

Dr. William Dahut, a researcher of prostate cancer at the National Cancer Institute, said the study supports earlier findings showing that hormonal treatments, which shut down testosterone production, are successful in killing cancer cells. In the Duke study, the flaxseed impeded the action of testosterone, which may spur the growth of tumors.

Dahut said a larger sample group exposed to a flaxseed diet for a longer period of time was needed to gauge if cancer growth continued to slow and if side effects occurred from decreased levels of testosterone. Such problems could include hot flashes, decreased sexual drive or breast enlargement.

``The benefit of 34 days of treatment is virtually unknown,'' Dahut said. ``But, potentially in certain patients with current prostate cancer who do not want full hormonal therapy, this may be a way to treat their cancer with less side effects.''

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