Flaxseed, which is rich in omega 3-fatty acids and fibre-related compounds known as lignans, may interrupt the chain of events that cause cells to divide irregularly and become cancerous, suggest researchers from the Duke University Medical Center in the United States.
"Our previous studies in animals and humans had shown a correlation between flaxseed supplementation and slowed tumour growth, but the participants in those studies had taken flaxseed in conjunction with a low-fat diet," said Wendy Demark-Wahnefried, a researcher in Duke's School of Nursing and lead investigator on the study.
"For this study, we demonstrated that it is flaxseed that primarily offers the protective benefit," she confirmed.
The study involved men scheduled to undergo surgery for the treatment of prostate cancer.
The researchers gave them 30 grams of flaxseed every day for an average of 30 days.
When the men's tumours were removed, the researchers were able to determine how quickly the cancer cells had multiplied.
The men taking flaxseed, either alone or in conjunction with a low-fat diet, were compared to men following just a low-fat diet, and men in a control group, who did not alter or supplement their daily diet.
Each group was made up of about 40 participants.
Men in both of the flaxseed groups had the slowest rate of tumour growth, according to the researchers.
The study was presented at the annual meeting of the American Society of Clinical Oncology in Chicago on Saturday.
NutraIngredients.com has not seen the full results, and publication status is unknown.
"The results showed that the men who took just flaxseed as well as those who took flaxseed combined with a low-fat diet did the best, indicating that it is the flaxseed which is making the difference," Demark-Wahnefried said.
She suggested that as a source of omega-3 fatty acids, flaxseed may alter how cancer cells lump together or cling to other body cells.
It could therefore help halt the cellular activity that leads to cancer growth.
Moreover, lignans may have antiangiogenic properties, meaning they are able to choke off a tumour's blood supply and stop it spreading, added the researchers.
Participants took the flaxseed in a ground form to make it more digestible and mixed it in drinks or sprinkled it on food such as yogurt.
The researchers now hope to test the effectiveness of flaxseed supplementation in patients with recurrent prostate cancer.
Over half a million news cases of prostate cancer are diagnosed every year worldwide, and the cancer is the direct cause of over 200,000 deaths.
Most worryingly, the incidence of the disease is increasing with a rise of 1.7 per cent over 15 years.