July 11, 2001 -- Ground flaxseed -- a grain that was a dietary staple in the 19th century -- may prevent the growth of prostate cancer and speed the death of tumor cells when combined with a low-fat diet, according to a small preliminary study.
Study author Wendy Demark-Wahnefried, PhD, tells WebMD that flaxseed can affect levels of the male hormone testosterone, which may influence the progression of prostate cancer. If confirmed by larger studies, the findings suggest that flaxseed could serve as a nutritional complement or alternative to using drugs or surgery to reduce testosterone in some men, she says.
In the study, 25 men with prostate cancer who were scheduled to have their prostate removed consumed a low-fat, flaxseed-supplemented diet for 34 days. Each day, they ate three tablespoons of the ground flaxseed, either sprinkled on cereal or mixed into other foods.
Following surgery, their tumors were compared with those taken from men who were not involved in the study.
Denmark-Wahnefried found some exciting results. "[W]hen we compared prostate tissue of men who consumed the diet prior to surgery, their tumor cells were not [growing] as quickly and were undergoing death at a much greater rate," she tells WebMD. She is associate research professor of surgery at Duke University Medical Center in Durham, N.C.
Men on the flaxseed diet also had lower levels of cholesterol and testosterone, and those with less aggressive disease showed a decrease in PSA, the marker commonly used to screen for prostate cancer.
Flaxseed has fallen out of regular use in modern days because it tends to spoil quickly. The grain is not often available in grocery markets but can be found in health food stores, notes Denmark-Wahnefried.
The grain is rich in both lignan -- a fiber believed to help regulate testosterone -- and omega-3 fatty acids, which have been shown to slow cancer progression in animal studies, she adds.
Nonetheless, she cautions that the study is very preliminary and requires far more research.
William Dahut, MD, is chief of the medical prostate cancer clinic at the National Cancer Institute. He called the findings "interesting" and said they support the already well-established recommendations for a low-fat diet, in general. But whether flaxseed, as a nutritional component itself, is affecting prostate tumors is difficult to know, he says.
For those who want to add flaxseed to their diet, Denmark-Wahnefried recommends ground flaxseed because the seed is naturally pointy and tough and can perforate the stomach.
In the meantime, patients with prostate cancer who would be candidates for hormonal therapy should still receive surgery or drugs that reduce testosterone.
"If you had prostate cancer and you were making a decision about hormonal treatment," says Dahut, "you [would] use the real stuff."