The Soy Controversy: More Questions Than Answers
Health Sciences Institute e-Alert
September 17th, 2001
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Dear Reader,
Ten days ago, we sent you a message on new research that was raising concerns
about the safety of soy. Since then, many of you have written back to us to ask
how you should alter your diet, or to point out apparent contradictions in the
soy research. (For example, wouldn't most Asians have
dementia and breast cancer based on their soy consumption?)
Understandably, we've all been distracted lately. But since the President and
other leaders have asked that we try to get back to "normal" as much as
possible, we wanted to answer the most common questions you raised about soy.
Before we address the science, we should address one overriding concern. Several
of you asked about the sources and reliability of the soy studies. If, for
example, cattle ranchers finance a study that shows soy isn't as safe as meat,
can the results be trusted?
We agree that knowing the source of the study's financial support is critical.
In this case, however, there are powerful and well-funded industries on both
sides of the debate. The dairy and agriculture industries may wish to discredit
soy. But companies like Archer Daniels Midland and Monsanto, some of the largest
suppliers of soy, have an interest in seeing this legume become commonplace on
our dinner tables.
It's also important to point out that HSI has absolutely no "soy agenda." We
will not benefit by having every member decide to abandon soy completely or to
eat only soy in the future. Our sole concern is to alert you to possible risks
that you may not be hearing about elsewhere, so you can
make an informed decision about how and whether to include soy in your diet.
Now, to your questions...
1) "If soy leads to dementia, breast cancer, and other conditions, why aren't
those diseases more prevalent throughout Asia, especially in Japan?"
According to information we've received from the Weston A. Price Foundation and
Dr. Joseph Mercola, the average soy consumption in Japan and China is close to
10 milligrams per day, which is about two teaspoons. (Original source: Fukutake
M, Takahashi M, Ishid K, Kawamura H, Sugimura T, Wakabayashi K; Food Chem
Toxicol, 34:457-61.) This is substantially lower than the amount consumed by
those Americans who use soy as a dairy or protein substitute.
Asians, you see, don't use soy as a protein replacement. They use it to
complement rich protein sources, such as fish. There's some conjecture --
although we were unable to locate a formal study -- that this combination with
other protein may mitigate some of soy's potential risks.
Furthermore, while Americans and Europeans eat a great deal of processed soy
(like tofu), Asians eat only carefully fermented soy (like Miso), using
processes to remove the natural toxins and preserve soy's benefits.
2) "I take soy lecithin to help lower cholesterol. Are the dangers associated
with soy lecithin the same as the potential dangers of soy protein?"
I spoke with Sally Fallon of the Weston A. Price Foundation. She explained that
the lecithin is basically the residual product left over after all the oil is
squeezed from the soybean. Therefore, she explained, the concentration of
pesticides in soy lecithin tends to be very high. I asked if that was the
primary concern and if it could be addressed by using organic soy in lecithin
production. She said yes, but warned that it's difficult to find organic soy
lecithin.
So concerns over soy lecithin arise from the possible presence of pesticides,
rather from risks associated with soy protein. And it's true that many studies
have indeed shown that soy lecithin can help lower cholesterol levels.
We should note one additional concern, however. We found information on Dr.
Mercola's website indicating that soy lecithin supplements given during
perinatal development could alter "synaptic characteristics in a manner
consistent with disturbances in neural function." (Original source: Bell JM,
Whitmore WL, Cowdery T, Slotkin TA, "Perinatal dietary supplementation with a
soy lecithin
preparation: effects on development of central catecholaminergic
neurotransmitter systems." Brain Res Bull 1986 Aug; 17(2): 189-95)
3) "I gave up dairy and switched to soy milk. Does the information you provided
relate to soy milk, as well? What other alternatives are there?"
An 8-ounce glass of soy milk contains approximately 20 mg of isoflavones, the
phytoestrogen found in soy. One study showed that a dose of 30 mg of isoflavones
per day affected thyroid function in Japanese women. Another study showed that
American women, who consumed 45 mg per day, demonstrated hormonal disturbances
after one month. (I'm having details of these studies mailed to me, so I can't
provide the citation here. However, I didn't want to delay responding to your
concerns any further.)
As far as alternative milk sources are concerned, there are several: rice,
almond, oat, and multi-grain. Unfortunately, they're not entirely free from
concern either. Rice milk, for example, has a higher sugar content than soy
milk. Some brands of almond milk contain corn syrup or brown rice
syrup. Depending on your tolerance level for sugars, they may prove to be a
better alternative. Still, you should read the ingredients carefully.
It's difficult for us to make a wholesale recommendation on this, as there are
both benefits and risks to eating soy. Dr. Jonathan Wright, M.D., advises his
patients and readers that, until the safety debate is better resolved, they
should restrict their soy consumption to no more than three servings per week.
While our goal at HSI is always to provide you with answers, we too feel there
are many open questions left in the debate over soy. We're continuing our
research and will keep you updated on any relevant developments. In addition,
we're putting together a more detailed research report
covering the benefits and dangers of soy.
To your good health, Jenny Thompson
For more on soy:
http://www.soyonlineservice.co.nz/