Flaxseed Can Be Protective Against Prostate Cancer

Duke University Medical Center (http://www.mc.duke.edu/) 

Posted 7/12/2001

http://www.sciencedaily.com/releases/2001/07/010712080024.htm

                 New Pilot Study Suggests Flaxseed And Low-Fat Diet 

                 Can Be Protective Against Prostate Cancer

                 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.

                 Note: This story has been adapted from a news release issued by Duke University 

                 Medical Center for journalists and other members of the public. If you wish to quote 

                 from any part of this story, please credit Duke University Medical Center as the 

                 original source. You may also wish to include the following link in any citation: 

                 http://www.sciencedaily.com/releases/2001/07/010712080024.htm