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Last Updated: Apr 16, 2008 - 5:52:06 PM |
FRIDAY April 11, 2008 (Foodconsumer.org) -- A new study suggests eating soy products such as tofu may significantly reduce women's risk of developing breast cancer, Reuters reported Friday.
The study involved more than 24,000 middle-aged and older Japanese women and it showed those with the highest levels of genistein were only one-third as likely as others to develop breast cancer over a period of 10 years.
The results were published in the Journal of Clinical Oncology.
Genistein is an isoflavone found in soybeans, which is structurally similar to the human hormone estrogen, meaning it can act like estrogen.
The effect of soy products on risk of breast cancer is not well understood and previous studies on the issue are inconsistent.
Scientists have already known that endogenous estrogen is probably tens of thousands times more powerful than estrogen-like phyto-chemicals when it comes to affecting the breast cancer risk.
Estrogen is a known risk factor for certain women. A common theory is that genistein could compete with the natural estrogen for estrogen receptors on body cells and reduce the risk of breast cancer.
"This finding suggests a risk-reducing rather than a risk-enhancing effect of isoflavones on breast cancer, even at relatively high concentrations within the range achievable from dietary intake alone," Dr. Motoki Iwasaki of the National Cancer Center in Tokyo and colleagues were quoted as writing.
For the study, participants were surveyed for their dietary habits and followed by an average of 10 years during which 144 women were diagnosed with breast cancer.
When these women were decided into four groups based on the level of genistein in their blood, the researchers found that those who consumed the highest were 65 percent less likely to develop breast cancer than the women who ate the lowest levels of genistein.
But moderate levels of the isoflavone were not linked to reduced risk of breast cancer.
The level of genistein in each participant in the study was measured in the blood, a practice that differed from many other studies. This means this current study may be more trustworthy.
Iwasaki was cited as saying that the findings suggest that high dietary intake of isoflavone may help reduce breast cancer risk. But it remains unknown whether the women in the western countries could have the same benefits.
In Japan and other Asian countries, consumption of soy starts from a young age. In the West, eating soy products is uncommon among young people.
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