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From: Ryan (
Subject:         Re: Soy Safety
Date: November 19, 2008 at 3:14 pm PST

In Reply to: Soy Safety posted by Evita on October 13, 2008 at 6:48 pm:

Hi Evita,
This is a subject that I am personally interested in as I am both a vegetarian (who loves soy products very much) and a Mathematician and Physicist(so scientifically bent).
I know that many studies have suggested that Soy is not the "miracle food" that it was once thought to be. (Its cholesterol reducing abilities have come under question lately for example.) Personally, I think the health food industry, like any other, tends to be sensational. It also follows social trends. My point- caveat emptor (buyer beware in Latin). Take what the health food gurus advise with a grain of sea salt. This does not mean that health foods are not health- many are- I just don't think taking spirulina will cure you of cancer, or following a macrobiotic diet will grow your arm back- the human body does have limitations.

Now, as a Mathematics graduate student I am always considering the effects of things I eat on my mind. Two studies have been published in the last decade which have suggested the possibility that tofu consumption in middle life could lead to dementia in later life. Neither of these studies is conclusive and both have issues which cause question. The Honelulu Heart study found a positive correlation between tofu consumption and the occurrence of dementia in elderly Japanese men.

Source article:

The issue here is that the study was not originally created to study this issue so it does not "correct" for other variables very well such as age, ethnicity, statistical background, etc... Further more, the FDA issued this statement in response to this study when prompted to rescind its allowance of soy health claims:

"FDA finds that this abstract does not provide a sufficient basis to
evaluate the merits and weaknesses of this study. As such, it is not
useful in evaluating the safety concerns at issue. Moreover, the report
does not provide information on total soy intake or what variables were
controlled in the analysis. If tofu or soy were implicated in
Alzheimer's disease, its prevalence would be expected to be higher in
Japan than in Hawaii, but White et al. (Ref. 115) found the prevalence
of Alzheimer's disease was higher in Hawaii than in Japan. Therefore,
FDA is not persuaded by the comment raising concerns about potential
adverse effects of soy protein in dementia and brain atrophy in older


The argument has been made that the higher incidence of dementia was due to Aluminum- I am VERY skeptical of this as Aluminum has NOT been proven cause dementia(I do, however, avoid aluminum anyway- in the spirit of scientific rigour though, that claim has not been substantiated yet).

The second study was a study specifically created to study the effects of Soy Consumption in Indonesia and also found a positive correlation between tofu consumption and poor cognitive test scores. I have a copy of this study (which is not available for free online- look to your local library or academic library for a copy).


I am still studying this one when I have time but really have no opinion of its scientific merit yet(the fact that I am not an expert in this field does not help either as I only know so much about science in the health fields). There is some question as to its accuracy as recently there were several cases of local merchants using formeldahyde as a preservative (which has been shown to lead to dementia). Some have jumped to the conclusion that the tofu used in this study was definitely treated with formeldahyde- I am not so convinced since treating food with formaldehyde is illegal in Indonesia.

Here is an article from 2006 regarding a food scare:

This article is dated January 2006, the data for this study was collected between April and June of 2006 and between December 2006 and February 2007.

This Formaldehyde scare definitely causes doubt regarding the strength of this study but I would not rule it out completely.

One interesting thing to note was the finding that tempe (a fermented soy product) actually found a negative correlation between consumption and dementia occurrence- IE tempe appeared to protect against dementia.

As a last thought regarding this study, I would like to acknowledge a paragraph in the conclusion of the journal article being discussed:

"There are several other explanations for the potential protective role of tempe intake combined with the negative effects of tofu. According to the Departments of Public Health at the Universities of Jakarta and Yogyakarta, formaldehyde is often added to tofu (but not tempe) to preserve its freshness. Formaldehyde can induce oxidative damage to the frontal cortex and hippocampal[memory center] tissue..."

I would like to point out that both of these studies are "intervention studies" meaning that people are surveyed on their eating habits. This makes conclusions sort of fuzzy since it becomes very hard to correct for all variables that may lead to your conclusion.

There is an other study that I have not read yet but may provide some interesting information: "The Okanawa Study". I know very little about it right now but plan to read it once this academic term ends.

The moral of the story from my end: there are a lot of questions of the table right now(I also want to note that these studies do not invalidate the health benefits of vegetarianism as a whole even if their conclusions are correct). Tofu certainly has a lot of great health benefits, but some potential shortfalls. There is no perfect food, so don't eat Soy exclusively, but I would not jump to too many conclusions yet. Also take care to truly evaluate each of the claims you hear. There are a lot of enemeies of soy that have a lot to gain by the demise of the soy industry (google search the Weston A. Price Foundation).

There is also a lot of money to be earned from soy and a lot of money to lose if soy is found to be bad for ones health- so many people will try protect the positive claims of soys' benefits by brushing off the science.
We also have the wishful thinking problem here that some people want a perfect food- some think this is Soy so they will defend the notion that soy is perfect.

I love soy- tofu is my favorite food- but its not a miracle, and it is possible it is killing my brain (I hope not). We will have to wait and see what happens in the next decade as far as research goes.

I hope this helps.
caveat emptor!

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