Update (11/6/2009):  It is common for me, lately, to be learning and instituting more things that I have time to write up as comprehensively as I’d like.  Regarding soy, although I think that there continue to be problems regarding soy, not the least of which has to do with the possible genetic modification of soy (as has been the case with wheat) and the chemicals used in soy’s preparation (see, for example, the Cornucopia Institute site).  People with thyroid problems should probably not consume large amounts of soy, and I have concerns for pre-pubertal children of both sexes.

However, I have modified my view of the uses of soy, or at least of soy protein, in therapeutic nutrition.  Here is a link to a 2004 position paper on soy put out by Metagenics.  The soy protein used in their products is from heritage seed (not genetically modified), with an organic pedigree back to the seed stock, grown organically, enzymatically digested to avoid poor utilization owing to medical problems). 

A series of reports recently appeared in the Townsend
Letter for Doctors and Patients
, detailing the history of soy
products, particularly soy protein isolates, from a dietary and toxic
point of view. Taken in its entirety, it is quite alarming. An article
in the next issue of the same journal, by a different author, criticized
many points that had been made, but in my opinion this is still a matter
for concern. (A more recent study with a different outcome is described
at the end of this section.)

At the Third International Soy Symposium, November 1999,
Lon White presented a paper at the Plenary session #9: Cognitive Function,
entitled “Association of High Midlife Tofu Consumption with Accelerated
Brain Aging.” This paper was reported in the Honolulu Star-Bulletin
(November 19, 1999) and subsequently appeared in papers such as the
Hartford Courant (where I first saw it). He reported a significant statistical
relationship between two or more servings of tofu per week and “accelerated
brain aging.” Those individuals who consumed tofu in midlife had
lower cognitive function in late life and a greater incidence of Alzheimer’s
Disease and dementia. An earlier study was cited which showed that post-menopausal
women with higher levels of circulating estrogen experienced greater
cognitive decline (Journal of the American Geriatric Society, 1998;
48:816-21).

In 1991, Japanese researchers reported that consumption of as little
of 30 grams (2 tablespoons) of soybeans per day for only one month resulted
in a significant increase in thyroid stimulating hormone. Diffuse goitre
(enlargement of the thyroid) and hypothyroidism (low thyroid hormone outputs)
appeared in some of the subjects. (Y Ishisuzi, et. al. in Nippon Naibunpi
Gakhai
1991 767:622-9)

The FDA toxicological section subsequently confirmed that the components
responsible for the effect on the thyroid were the isoflavones (genistein
and diadzen) (Divi, RL,et. al., Anti-thyroid isoflavones from the soybean.
Biochemical Pharmacology, 1997 54:1087-1096)

These isoflavones are touted as “hormone modulators” and are
being consumed by many women seeking to mitigate the effects of menopause.
But in animals, these products are known as endocrine “disruptors”
and can cause decreased fertility, congenital birth defects, and premature
death.

Twenty-five percent of bottle-fed infants in the United States receive
soy-based formula. It has been estimated that an infant fed exclusively
soy forumula receives the estrogenic equivalent (based on body weight)
of at least five birth control pills daily (WM Keung in Biochemical
and Biophysical Research Committee
1995 215:1137-1144.)

It has been reported that the age of entering puberty for girls has significantly
decreased. Investigators found that 1% of all girls show signs of puberty,
such as breast development or pubic hair, before the age of 3.
By age 8, 14.7% of white girls and almost 50% of African-American girls
had one or both of these characteristics (Herman-Giddens, et. al., Pediatrics
April 1997, 99:(4) 505-512). It is known, of course, that environmental
pollution, such as with PCB and DDE may cause early sexual development
in girls. The WIC program stresses soy formulas for African Americans
because of the high incidence of lactose intolerance in that population
group.

In the 1986 Puerto Rico Premature Telarche Study (telarche means the
onset of puberty), the most significant dietary association with premature
sexual development was soy infant formula (American Journal of Diseases
of Children
December 1986 140:(12): 1263-1267).

This information regarding soy protein was gleaned from a
report by Sally Fallon and Mary G. Enig, PhD, both associated with the
Weston A. Price Foundation.
This foundation is based on the pioneering work of Weston A. Price,
who chronicled the negative effects changes from a traditional diet
on the health of population groups around the world.

An article published in the 8/15/01 issue of the Journal
of the American Medical Association (Exposure to Soy-Based Formula in
Infancy and Endocrinological and Reproductive Outcomes in Young Adulthood,
Strom, et.al) studied over 30 criteria, some related to female reproductive
function, in people who had been fed soy formulas as infants (who had
participated in controlled feeding studies as infants). This group was
composed entirely of Caucasians, and did not look at thyroid function.
In this group, however, there was no difference in the age of onset
of puberty (as self-reported by the participants) in the soy fed group
as compared to controls. There was an increase in discomfort associated
with the menses, and a longer duration of menstrual bleeding. One of
the lead investigators has received financial support from soy formula
manufacturers (this was disclosed in the article).

Taken all together, despite the negative findings in the
recent study, in my opinion this information should promote caution
in the use of soy products for infants, children, and adults. I have
the impression that the strongest case against soy products is presently
most applicable to infants and children. In any case, the use of any
one or few foods as opposed to a broad variety of foods is probably
unwise for many reasons. The one obvious exception is the use of breast-milk
for babies.

11/2/01 — the controversy in the alternative medical literature
continues to rage regarding the original article which prompted my writing
this page. Many of the contentions of Fallon and Emig have been criticized
by several authors. In all probability, there is no great cause for
concern. Still, it makes sense to not rely on one or a few food sources
for nutrition. In addition, to my way of thinking, we should use food
as nutrients for a healthy body, but not as medicine. There are many
in the alternative health community who would disagree with this, of
course.