Posted on 01/23/2006 1:12:59 PM PST by PeaceBeWithYou
Eating veggie burgers and tofu to lower "bad" cholesterol may not help, a new review of soy's health benefits suggests.
The American Heart Association reviewed 22 randomized trials comparing soy protein and the soy component isoflavone to milk or other proteins.
The majority of the trials concluded soy led to an average decrease in LDL or "bad" cholesterol levels of just three per cent.
"This reduction is very small relative to the large amount of soy protein tested in these studies, averaging 50 grams, about half the usual total daily protein intake," the committee wrote in the Jan. 17 online issue of the journal Circulation.
Soy had no effect on HDL, or "good" cholesterol, or on blood pressure.
Soy and isoflavone also didn't seem to reduce symptoms of menopause, such as hot flashes.
Its ability to slow postmenopausal bone loss showed mixed results.
As for cancer, clinical trials on whether soy can help to prevent or treat breast, endometrium and prostate cancer haven't shown that the food works or is safe, and warn of possible side-effects.
"For this reason, use of isoflavone supplements in food or pills is not recommended," the panel concluded.
The findings could lead the U.S. Food and Drug Administration to reconsider whether food companies in the U.S. can continue to tout the cholesterol-lowering benefits of soy-based foods on product labels.
Soy-based foods could still help because of their high content of polyunsaturated fats, fibre, vitamins, minerals and low saturated fat content, the study's authors noted.
Dieticians have agreed that soy may be beneficial when eaten instead of less nutritious foods such as hamburgers or hot dogs.
Current science disagrees with the obscure encyclopedia citation. Your link is quite interesting but isn't credible to me - this Dr. Peat does his readers a great disservice by mixing facts with half truths and coming to some wild conclusions. For instance, it is true that the body can assemble a variety of fats. Some, but not all. It can make saturates. It can make unsaturates. It can make w7's and w9's, it can make Mead acid, but it cannot make the w6's and w3's. Hence they're called "essential".
In the past, when the fatty acids were first identified they were called "essential" for normal growth and development. In today's science, the term "essential" has a much narrower definition. It means the substance cannot be synthezied in the body and must be obtained from dietary sources. Because some fatty acids can be synthesized by the body they are obviously not 'essential' by current definition. I think the encyclopedia excerpt is attempting to clarify this point and as such does nothing to refute what is settled science. To the extent that it names w3 and w6 as non-essential, it is simply wrong.
Again, I'd be very interested in reading something (fairly current) from a peer-reviewed journal that establishes the pathways for w6 or w3 synthesis in the human body. Perhaps this Dr. Peat has published such revolutionary research. I doubt it. In the mean time, I encourage you to read more widely and to challenge what you read by looking at the supporting science.
Here's a start: W.E.M. Lands (1992). Biochemistry and physiology of n-3 fatty acids. FASEB J 6: 2530-2536.
Another reference of interest is Mary Enig's "Know Your Fats" which is written as a primer to lipid chemistry. She also makes the case that unsaturated seed-oils are not health-promoting but does a far better job of it.
Thanks for your informative reply. And for those that aren't used to translating between the Roman and Greek alphabets, when you write w3, you refer to a fat that many of us refer to as omega-3.
I suspect topics like soy, cholesterol, antioxidants, alcohol consumption, etc, that go back and forth, good one day, bad the next, are never going to fit to a line or a hyperbola or anything simple. Not with genetics, metabolism, nutrition, environment, and pharmecuticals all interacting with each other. We just have to hang in there and keep learning.
And ugh. There are four names for everything in biochemistry. omega-3's, w3's, n-3's, PUFA's, It's just crazy. :0
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