Ancient Food, Modern Prostate Help
Pilot study finds combination of flaxseed and diet may help against this cancer
By Fran Berger
WEDNESDAY, July 11 (HealthScoutNews) -- A food with a 5,000 year history may have some modern-day benefit: protecting against prostate cancer, the leading cancer among American men, a new study says.
"Flaxseed is the richest source of plant-based omega-3 fatty acids, which have been shown to reduce tumor growth in animals," says the study's lead author, Wendy Demark-Wahnefried, an associate research professor and nutrition researcher in the department of surgery at Duke University.
In addition, flaxseed has a high lignan content, says Demark-Wahnefried. "These are very complex, fiber-related compounds that bind testosterone in the gastrointestinal tract," and may play a role in suppressing the growth of prostate cancer cells. Testosterone, a "male" hormone, tends to spur growth of certain cancers.
In this pilot study, researchers used 25 men who were all due to undergo surgery for removal of a cancerous prostate, and put them on a 34-day, low-fat, flaxseed-supplemented diet.
The men's levels of prostate specific antigen (PSA) -- a sign of the presence of prostate cancer -- free androgen and total blood cholesterol were taken at the beginning of the study. The tumors that were removed were matched against 25 historic cases, equal in age, race, PSA level at diagnosis and grade of tumor.
The researchers report that, on the diet, the men had much greater decreases in cholesterol and testosterone, yet there was no decrease in libido or any other sexual dysfunction.
The measures of tumor growth, says Demark-Wahnefried, showed a greater rate of tumor cell death after the diet, and decreased PSA levels were found in men with early stage prostate cancer.
Those with more aggressive cancer, however, had PSA levels that continued to rise.
"It has been known that flaxseed is good for breast cancer and colon cancer, so it's not surprising that it's useful for prostate cancer," says Mindy Green, director of education for the Herb Research Foundation in Boulder, Colo.
"Although these results are compelling, there's much yet to be done," says Demark-Wahnefried. She suggests further research that would include men without prostate cancer to see whether there is a protective effect -- a difficult task. "By the time the PSA rises, men usually have prostate cancer."
And, randomized trials are necessary to separate the flaxseed supplements from the low-fat diets to see which is reducing the tumor growth, or whether it's the combination, she adds.
But adding whole flaxseed to a diet that is well balanced and full of fruits and vegetables couldn't hurt. Demark-Wahnfried advises you use ground flaxseed only to eliminate any pointy edges that could perforate the intestines.
Green disagrees. "Flaxseed turns very slimy and mucilaginous when soaked in water, so you can use it whole once it's softened. But you should be sure to drink plenty of water to prevent bowel obstruction as the flaxseed expands."
The study appears in the July issue of Urology.
What To Do:
"Buy flaxseed fresh, then grind it in your coffee grinder and store it in the freezer. The fresher the better, so make sure it's freshness-dated within three months of pressing," says Green.
But don't cook with it. "Heat breaks it down and destroys the valuable compounds. I make a salad dressing with it, mixing it half and half with olive oil, or add it to butter and made it spreadable."
SOURCES: Interviews with Wendy Demark-Wahnefried, Ph.D, R.D, associate research professor, nutrition researcher, department of surgery, Duke University, Durham, N.C., and lead author; Mindy Green, M.S., director of education, Herb Research Foundation, Boulder, Colo.
AUA 98th Annual Meeting, 4/03
Intl J Cancer, 8/04
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