Qi Spot

Conventional wisdom dictates that since soy products contain products similar to estrogen, and that estrogen “feeds” certain types of cancer cells, then soy products in theory could make some breast cancers worse.  New research implies the opposite.

http://www.latimes.com/news/nationworld/nation/la-sci-soy9-2009dec09,0,6546847.story

Shari Roan writes,

Soy foods do not appear to increase the risk of breast cancer recurrence among survivors of the disease and may even confer some health benefits, new research suggests.

The study, published in today’s issue of the Journal of the American Medical Assn., should reassure breast cancer survivors that they need not scrupulously avoid soy foods, which have become increasingly popular in the United States in recent years. Research in animals has indicated that soy might increase the chances of breast cancer recurrence because it can act like the hormone estrogen, which promotes tumor growth.

So we CAN have our tofu and eat it, too!  What’s the “theory” behind how it makes cancer worse?  The isoflavones found in soy!

“Isoflavones can act as estrogens and add to the circulating pool of estrogen that is available and promote tumor growth. That is the concern,” said Bette J. Caan, a senior nutritional epidemiologist at Kaiser Permanente in Oakland, who was not involved in the current study.

Let’s see what the evidence says:

“Some doctors have advised women not to eat soy foods,” said Dr. Xiao Ou Shu, a professor of medicine at Vanderbilt University and lead author of the paper. “But another school of physicians think it’s safe. So it has been controversial. Our findings are important because, nowadays, it’s very difficult to avoid soy exposure. Soy flour and soy protein has been added to many foods in this country. Women may consume it and not even know it.”

Shu and her colleagues analyzed data from the Shanghai Breast Cancer Survival Study of 5,042 women in China. The breast cancer survivors were ages 20 to 75 and were followed for an average of four years.

The study showed that the higher a woman’s intake of soy foods, the lower her chances of cancer recurrence and death. Patients with the highest intake had a 29% lower risk of death during the study period and a 32% lower risk of breast cancer recurrence compared with patients with the lowest intake of soy foods. Soy food intake was measured by either soy protein or soy isoflavone intake. Isoflavones are hormones found in plants.

Ah ha! But this is just one study.  What about others? Maybe this is just a fluke?

In research released earlier this year, Caan and colleagues at UC Berkeley also found that higher soy intake was linked to lower rates of breast cancer recurrence. That study, published in the journal Breast Cancer Research and Treatment, followed almost 2,000 U.S. breast cancer survivors.

Okay. Not a fluke.  Does this mean people should go out and stuff themselves with tofu?

“We do not see a harmful effect of soy. That is the main message out of both studies,” Caan said. “Breast cancer survivors shouldn’t go out and take soy supplements, but they shouldn’t be afraid to drink soy milk in their coffee or eat tofu.”

Can Tofu help prevent breast cancer recurrence?

What about differences between the breast cancer that responds to estrogen and those that don’t? The ones that take tamoxifen and not?

Shu’s study found no adverse effects from soy food intake among women whose tumors grow faster because of exposure to estrogen, called estrogen receptor-positive breast cancer, or among those whose cancers are unaffected by estrogen, called estrogen receptor-negative.

Nor were there differences in the findings among women who used the breast-cancer drug tamoxifen and those who did not. However, the study found that the drug was related to improved survival only among women who had low or moderate soy food intake, not higher intakes.

Ah, so don’t take too much.  Typical Chinese philosophy.  Also typical is the philosophy stated below:

“We cannot conclude from this study that there are no negative effects” from soy, she said. “We are studying soy as a whole food. We are not studying its components. It could be some components are not good for some people. But overall, we see women who eat a high amount of soy with better outcomes.”

There we go.  They’re looking at this like TCM doctors do: look at the WHOLE food, not just the individual components.

So what does TCM have to say about soy and it’s estrogen wanna bes?  Check this out from http://www.tcmpage.com/hpmenopause.html

Some of the most interesting research for those concerned with women’s health issues has been done in the field of plant chemistry, and specifically in studies of chemicals called phytoestrogens. Phytoestrogens are chemicals produced by certain plants which resemble the estrogens that are produced by the human body, and which bind readily to estrogen receptors in the human body, but which are “weaker” forms of estrogen than human estrogen. Scientific studies suggest that higher levels of “strong” estrogen correlate with higher incidence of breast cancer in women. That is why women with a history of breast cancer, or a high risk of developing it are not recommended to be on hormone replacement therapy. Unfortunately, women in Western countries are exposed to higher levels of environmental estrogen than women in undeveloped countries. It is estimated that our environment adds 40% more “strong” (and harmful) estrogens to the body than are produced naturally. This could explain why the incidence of breast cancer is higher in developed countries, and is probably a complicating factor in many hormone-related conditions. The benefit of eating foods which are high in phytoestrogens, like soy beans, is that the “weak” estrogen of the plant binds to the body’s estrogen receptors, displacing the “strong” estrogens, which are then discharged harmlessly from the body.

So the docs were right all along: eat your veggies!  I must warn though, that since soy milk is very cooling and yin, it might be damaging to the yang natures of children or those with too much cold in the body.  This could lead to bloatedness and other digestive problems.