From: Ian Goddard (Ian@goddard.net)
Date: Sat Nov 27 1999 - 02:24:45 MST
http://starbulletin.com/1999/11/19/news/story4.html
Too much tofu induces ‘brain aging,’ study shows
A Hawaii research team says high consumption
of the soy product by a group of men lowered
mental abilities
By Helen Altonn
Star-Bulletin
Tofu is touted for its health benefits, but also may
pose health risks, says a Hawaii scientist.
A Hawaii study shows a significant statistical
relationship between two or more servings of tofu a
week and "accelerated brain aging" and even an
association with Alzheimer's disease, says Dr. Lon White.
The Pacific Health Research Institute researcher urged
caution at a recent conference in Washington as scientists
from around the world discussed the role of soy products
in the prevention and treatment of disease.
The symposium was sponsored by giant soybean growing and
processing firms such as Archer Daniels Midland and DuPont.
The largely unregulated food supplements industry is
preparing to step up sales, claiming that isoflavones,
plant chemicals found in high concentrations in soybeans,
offer "natural" cures for breast cancer, osteoporosis,
prostate cancer, heart disease, menopausal "hot flashes"
and other chronic conditions.
Negative conclusions
But, White said in an interview, "The majority of
scientists said the data they were talking about for
beneficial effects on health is very weak" and doesn't
really support health claims for soy foods. White and
his associates have been studying diseases and aging
in a group of Japanese-American men who volunteered for
medical research in 1965. The Honolulu Heart Program
began with 8,006 men born from 1900 through 1919. They
were identified through World War II Selective Service
registration records.
In comparing the dietary habits and health of the
Japanese-American men in the study group between 1965
and 1993, White said the scientists found "a significant
link between tofu consumption during midlife and loss of
mental ability and even loss of brain weight."
The men were questioned about 27 foods and drinks, with
data showing that those who ate more tofu were apt to
have impaired mental ability, White said. Tofu was the
only consistent link among the men, he said. The rate
of brain impairment, which normally increases with age,
also went up faster in the men who ate the most tofu, he said.
"The test results were about equivalent to what they
would have been if they were five years older," he said.
"Guys who ate none, their test scores were as though
they were five years younger."
The brains of 300 men who died also were examined in a
unique autopsy study conducted as part of the Honolulu
aging project, White said. The 300 men didn't appear to
have had any more strokes than the average person, and
their blood vessels didn't look different.
"But what I did see was (that) the simple weight of the
brain was lower," he said. Shrinkage occurs naturally
with age, but atrophy progressed more rapidly in those
men who had consumed more tofu, White said.
He said the wives of about 500 men also provided
information about what they ate, and the findings
correlated with what their husbands said.
Stark contrast
So the scientists obtained four independent indicators of
an adverse effect from frequent eating of tofu and changes
in the brain with aging, White said. Those who ate a lot of
tofu, by the time they were 75 or 80 looked five years
older, he said.
"Why in the world would that happen?" he said. "Everyone
knows protein in tofu and soy is wonderfully nutritious.
Everyone knows fats are wonderfully nutritious.
"But more and more and more over the last five to 10 years,
people have been claiming the health benefits of soy foods
are less related to its nutrient composition, proteins and
fat, and more related to other molecules that occur in tofu
made by soy plants and act as pharmacological agents."
Isoflavones, the most talked about, "are molecules that the
soy plant makes while it's germinating to help it fend off
mold and other things that attack the plant in the ground,"
White said.
They're plant molecules that look like estrogens but
they're not natural estrogens, he said. "When they get
into cells, they actually affect the metabolism of cells.
They inhabit certain kinds of enzymes and alter (the)
metabolism of cells.
"The bottom line," stressed White, "is these are not
nutrients. They are drugs. They will have some benefits
and some negative things."
Groundbreaking work
White said his study, to his knowledge, is the only one
to show strong evidence of serious adverse effects from
a soy product. His group is seeking a new National
Institutes of Health grant to continue research on the
effects of tofu. It may be beneficial for heart disease
and bones, White said. "We don't know. All we know, in
our study, is there appears to be an adverse relationship."
Among those at the conference was Finnish scientist Herman
Adlercreutz, who became interested in soy after observing
that breast cancer and colon cancer were less common in
Japan than in Finland. His studies 20 years ago led to a
scientific explosion of interest in soy and its components.
Adlercreutz believes more dietary soy, a staple of Asian
diets, would improve the health of Americans and people
of other Western countries. But he said at the conference,
"I am myself frightened a little bit by all of this.
There is so much we don't know."
Mark Messina, a soy foods expert and former researcher
with the Diet and Cancer Branch of the National Cancer
Institute, told the scientists, "It's simply not possible
as yet to draw any conclusions about soy consumption and
cancer prevention, but further research is certainly warranted."
Companies that make money from soy products are pushing
hard to have people think of them as "perfect food," White said
"But if we're talking about soy foods containing substances
that have effects on health that aren't nutrients, that are
not vitamins, or fat, but change how cells operate, they're
acting as drugs act. And the way we think of them should be
how we think about drugs."
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