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In the Vegetarian & Vegan News...

Soy Research Update
by Jeff Nelson

For a variety of motivations, soy seems today to be cast either as the cure or cause of nearly every ill known to man. On one side you have nutritionists and researchers touting soy's many alleged benefits (and yes -- some receive a lot of money from the soy industry, including some of the best known vegetarian researchers on the subject). On the other side are a few researchers who loudly repeat again and again the results of one questionable study, or who latch onto and look to amplify wherever possible some admittedly troubling but highly preliminary research results, using these to try to create an anti-soy hysteria.

By the way, the same people and industries targeting soy are curiously silent when it comes to broadcasting the known, far better documented and generally more serious and far-reaching health problems associated with consumption of meat and dairy products. As the saying goes when reading releases and reports from either side: follow the money to find the probable bias.

John McDougall, MD, has a terrific article about soy in his latest newsletter. (You can subscribe from his website.

McDougall discusses the high fat content of soybeans (46% fat, 38% protein). (Yes, eating lots of soy can make you fat!)

And he talks at length about phytoestrogens in soy, which he says are the key to soy's health benefits -- and risks. After an explanation of what is known about phytoestrogens, McDougall says the bottom line is that not enough research has been done to allow us to fully understand them and their effects on the body.


 



Soy isoflavones are theorized to protect against cancers like breast cancer because they lower estrogen in the body. Some animal research supports this hypothesis, he says, but there have been no large, long-term clinical human trials to support it.

While isflavones may or may not turn out to protect against cancer, it may turn out that the reverse is true, and plant estogens may work the other way. He notes that some fear phytoestrogens may cause problems by artificially altering the hormonal balance, and says there is cause for concern. In the study of 48 women with benign or malignant breast disease, for example, a daily supplement of 60 grams of soy (45 mg of isoflavones) was linked to breast-tissue proliferation (a sign of increased risk of breast cancer). But McDougall says more research is needed before we can conclusively say how these plant estrogens affect the human body, and the jury is still out.

Many of soy's purported health benefits are based on cicrumstantial evidence, says McDougall, such as the fact that populations with a traditionally high soy intake have lower rates of many "Western" diseases. Soy *may* have something to do with it, he says, but then again it may not. McDougall feels the focus on soy ignores the many other factors that enter into the equation, such as fat and fiber intake, environmental and chemical contaminants, and level of physical activity.

Regarding the study in Hawaii that found that men were more likely to have cognitive impariment or Alzheimer's disease if they ate tofu more than twice a week, McDougall remarks that this is just one isolated study, and further research is clearly needed to clarify the results.

Earlier this year when considering whether it would permit health claims for soy, the FDA rejected the abstract of the Hawaii study for a few reasons, including the fact that if the study results were valid, there would be more dementia and Alzheimers in Japan than in Hawaii (because more soy is consumed in Japan) -- but the reverse is true, suggesting it wasn't an effect from soy consumption the researchers may have been seeing.

Bill Harris, a vegan MD who lives in Hawaii, strongly suspects that if the results of the Hawaii "brain-aging" study turn out to be valid, it may be that aluminum -- used in the refining of some soy products in Hawaii -- is the actual culprit. Harris went out and had soy products from Hawaii tested against soy products from the mainland. He had a lab do the tests and paid for them himself. The lab found the levels of aluminum in the Hawaii products to be signifcantly higher. (See http://www.vegsource.com/harris/brain_aging.htm ) Harris quotes a number of studies which support the relationship between aluminum consumption and Alzheimers, and he recently sent me another published in a French medical journal in July 2000 showing that traces of aluminum in drinking water significantly increased the risks of dementia and Alzheimer's disease. This was a large study of 3,777 people with a followup after 8 years which suggested a strong cause/effect between aluminum and the kinds of brain problems reported in the Hawaii study and attributed by the researchers to tofu.

The aluminum factor currently seems like a very possible explanation for the alleged "brain aging" properties of soy -- many Hawaiian tofu-eaters are eating a lot of aluminum, too. Not so curiously, none of the soy manufacturers which Dr. Harris contacted with the results of his study ever responded. It would probably be very costly for those Hawaiian soy manufacturers to replace their tubes and processing equipment with non-aluminum parts. So what to do to be prudent? Don't eat soy products from Hawaii...!

In his newsletter McDougall also points out the fact that the health claims about soy which are supported by the most evidence -- are the positive effects of soy on cholesterol and cardiovascular health. There are some 40 studies showing soy lowers cholesterol, even when you remove the fiber.

McDougall's bottom line is that soy *can* be part of a healthy diet, but he says if you don't eat it already,don't start just because you think it's "health food." He advises using soy like a condiment to add variety and versatility to a plant-based diet. Sprinkle soy cheese on your baked potato, pour soymilk on your cereal in the morning, have a soy/veggie burger now and then, but stick to veggies, fruits and whole grains as the foundation of your diet.

See also: Alzheimers: Losing Your Mind for a Sake of a Burger

 

 

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