PROSTATE Cancer & Flaxseed Study

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Sunday, April 21, 2002 10:45 PM

PROSTATE Cancer & Flaxseed Study

 

 

Med- http://www.dukenews.duke.edu/med/flaxseed.htm -

 

 

July 11, 2001Duke News Service

Duke University

Box 90563, 615 Chapel Drive, Durham, North Carolina 27708-0563

Phone: (919) 684-2823 ~ Fax: (919) 681-5570

Contact: Amy AustellPhone: (919) 684-4148amy.austell

 

 

NEW PILOT STUDY SUGGESTS FLAXSEED AND LOW-FAT DIET CAN BE PROTECTIVE AGAINST

PROSTATE CANCER

 

Note to editors: Wendy Demark-Wahnefried can be contacted at (919) 681-3261

or demar001. A photograph of Demark-Wahnefried is available at

http://photo1.dukenews.duke.edu/pages/ in the Medical News Service folder as

" Demark-Wahnefried.jpg. "

 

DURHAM, N.C.--A low-fat diet supplemented with flaxseed may help reduce the

risk of prostate cancer, researchers from Duke University Medical Center

report in the July issue of Urology.

 

The researchers said dietary fat and fiber can affect hormone levels and may

influence cancer progression. Flaxseed is high in fiber and is the richest

source of plant-based, omega-3 fatty acids. Studies suggest that dietary

fiber reduces cancer risk, and omega-3 fatty acids also have shown a

protective benefit against cancer. Flaxseed is also a rich source of lignan,

a specific family of fiber-related compounds that appear to play a key role

in influencing both estrogen and androgen metabolism.

 

" We thought flaxseed would be the perfect food for prostate cancer

patients, " said lead author Wendy Demark-Wahnefried, associate research

professor in the department of surgery at Duke. " It's full of omega-3 fatty

acids, fiber and lignan. Testosterone may be important in the progression of

prostate cancer, and lignan in the flaxseed binds testosterone, so we

thought the flaxseed might suppress the growth of prostate cancer cells. By

pairing a low-fat diet with the flaxseed supplement, we also thought we

could maximize the effect of the omega-3 fatty acids, since studies in

animals show that the kind of fat we eat may be important for cancer

progression. "

 

The pilot study involved 25 patients with prostate cancer who were awaiting

prostatectomy (surgical removal of the prostate). Baseline levels of

prostate-specific antigen (PSA), testosterone, free androgen index and total

serum cholesterol were determined at the beginning of the study. The tumors

of those on the diet were then matched with 25 historic cases, equal in age,

race, PSA level at diagnosis and biopsy Gleason sum (a scoring system used

to grade prostate tumors) to compare tumor progression and biomarkers after

the dietary intervention.

 

The men were on the low-fat, flaxseed-supplemented diet for an average of 34

days. Finely ground flaxseed was used in the study because, in its natural

form, flaxseed is a pointy, tough seed that can puncture the intestines when

consumed in the amounts used in this study (three rounded tablespoons a

day). The ground flaxseed in the study was vacuum-packed (ground flaxseed

can quickly go rancid) and had added emulsifiers for ease of mixing. The men

were instructed to sprinkle the flaxseed on their cereal or mix it into

juices, yogurt or applesauce. Researchers reported good compliance with the

diet and said it was tolerated well.

 

At the end of the study, the researchers observed that the men on the diet

had significant decreases in cholesterol, and both total and free

testosterone. While there was a decrease in testosterone levels, they noted

that none of the participants in the study suffered decreased libido or

sexual dysfunction. There was a trend toward a decrease in PSA levels in men

with early-stage prostate cancer (Gleason sums of six or less), but in men

with advanced prostate cancer (Gleason sums of more than six) PSA levels

continued to rise.

 

" It's not surprising that a diet therapy that was only taken for an average

of 34 days had little effect on men with aggressive disease, "

Demark-Wahnefried said. " But what we did see was that for the men on the

diet, their tumor cells did not divide as quickly and there was a greater

rate of apoptosis (tumor cell death) in this group. "

 

With such a short-term dietary intervention, the researchers said they did

not expect to see a difference in tumor biology between the diet-treated

patients and the control patients, but were encouraged by the lower

proliferation rates and significantly higher rates of apoptotic cell death.

However, they said the results should be interpreted with caution, stressing

that randomized controlled clinical trials are needed to confirm the results

of the pilot study. Research on mice models is currently under way, and

preliminary results support the findings in humans.

 

Demark-Wahnefried said it is still unknown if the low fat diet or the

flaxseed--or a combination of the two--is the active component in the tumor

reductions, adding more studies examining these elements independently are

needed.

 

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