A new US study suggests that flaxseed, which
is rich in omega 3 fatty acids and lignans,
can stop prostate cancer tumours from growing.
The study was presented at the 43rd annual
meeting of the American Society of Clinical
Oncology (ASCO) in Chicago on Saturday by
researchers from Duke University Medical
Center, Durham, North Carolina.
The researchers think that flaxseed, which
has similar properties to sesame seed, probably
interrupts the chain of events that eventually
makes cells multiply out of control and
become a tumour.
Demark-Wahnefried, a researcher in Duke's
School of Nursing and lead investigator
on the study said that: "Our previous
studies in animals and in humans had shown
a correlation between flaxseed supplementation
and slowed tumor growth, but the participants
in those studies had taken flaxseed in conjunction
with a low-fat diet." However, she
explained that: "For this study, we
demonstrated that it is flaxseed that primarily
offers the protective benefit."
was funded by the National Institutes of
Health, and researchers at the University
of Michigan and the University of North
Carolina at Chapel Hill also took part.
Demark-Wahnefried and colleagues recruited
161 men who were due to have surgery for
prostate cancer (prostatectomy: where all
or part of the prostate gland is removed).
The patients were randomly assigned to one
of four groups. One group took 30 grams
of flaxseed a day for an average of 30 days
before they had the operation (the flaxseed
only group). Another group did the same
but also followed a low-fat diet (20 per
cent or less of their calories from fat).
A third group did not take the flaxseed
and only followed a low-fat diet, while
the fourth group, a control, had none of
surgery, the researchers examined the tumour
cells under a microscope to assess how quickly
they had multiplied. They then compared
the men who had only flaxseed, with or without
following a low-fat diet, with the men in
the other two groups: no intervention and
low-fat diet only. They found that the slowest
rate of tumour growth occurred in the two
flaxseed supplemented groups. Demark-Wahnefried
said: "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."
The flaxseed supplement was given in ground
form because in the whole form the seed
coat is hard and undigestible. The patients
took the flaxseed either in drinks, sprinkled
on food, or with yogurt.
is thought to stop the growth and spread
of cancer cells. This could be because the
omega-3 fatty acids it contains interferes
with the ability of cancer cells to cling
onto other body cells, said Demark-Wahnefried.
The lignans it contains may also have antiangiogenic
properties, the ability to stop the blood
supply to the tumour. Demark-Wahnefried
said that they were "excited that this
study showed that flaxseed is safe and associated
with a protective effect on prostate cancer".
In next phase of their research the team
hopes to study the preventative properties
of flaxseed, and its effect on patients
with recurrent prostate tumours. As well
as being antiangiogenic, the lignans in
flaxseed, one of the richest sources of
these fibre-related compounds, are thought
to interfere with or prevent cell division
and affect hormones. They are antimitotic,
affect androgen metabolism and have estrogenic
effects, said Demark-Wahnefried.