Plant Estrogen May Cut Breast Cancer
Lignans -- Found in Tea, Plants -- May Reduce Breast Cancer Risk After Menopause
March 20, 2007 -- A diet rich in estrogen-like compounds found in flaxseed,
tea, and many plants may help curb breast cancer after menopause.
That's according to a French study published in the Journal of the
National Cancer Institute.
The study included about 58,000 postmenopausal French women who were
followed for an average of more than seven years.
When the study began between 1993 and 1997, the women were in their early
50s, on average, and didn't have breast cancer. They completed surveys about
their diet and lifestyle, including how often they consumed 208 foods and
Researchers included Francoise Clavel-Chapelon, PhD, of France's Institut
National de le Sante et de la Recherche (INSERM), which is France's institute
for biological, medical, and public health research.
Levels of Lignans
Using the completed dietary surveys, Clavel-Chapelon and colleagues
calculated the women's daily intake of lignans, which are a type of plant
estrogen found in many plants.
On average, the women consumed 1 milligram per day of lignans, with daily
lignan intake ranging from 0 to 5 milligrams.
The women got their lignans from fruits, vegetables, tea, coffee, and grain
products including bread, breakfast cereals, rice, and pasta.
Flaxseed, which is particularly high in lignans, isn't part of the
traditional French diet, but it may be becoming more common in French
multigrain bread, the researchers note.
More Lignans, Less Breast Cancer
A total of 1,469 women in the study group were diagnosed with breast cancer
during the follow-up period.
Women with the highest lignan intake were 17% less likely to be diagnosed
with breast cancer during the study than those with the lowest intake.
Those findings take other breast cancer risk factors into account.
However, the study didn't track soy consumption. Soy contains isoflavones,
which are plant estrogens that aren't lignans.
Lignans were only linked to a reduced risk of breast cancers that are
sensitive to the hormones estrogen and progesterone.
One More Reason to Eat Plants, Grains
The French study didn't directly test lignans against breast cancer, so the
findings don't prove that lignans lower breast cancer risk.
But Clavel-Chapelon and colleagues say their findings support
recommendations for women to eat diets consisting largely of fruits,
vegetables, and grain products, which are all good sources of lignans.