looks at Hawaii
The study suggested a strong
link between the food
and faster aging
Soy industry has its argumentsBy Helen Altonn
A Hawaii research paper suggesting a strong link between tofu consumption, faster aging and brain impairment again is making headlines, this time in the current Journal of the American College of Nutrition.
The Star-Bulletin reported the findings last November by Dr. Lon White of the Pacific Health Research Institute and his colleagues. Tofu sales dropped, although researchers emphasized then, and point out again, that while the study is valuable, it's based on observations and isn't conclusive.
White acknowledges, "The real weakness of the study is it's not a trial; it's an observational study.
"The results must be considered worrisome but cannot be considered established without other confirming findings from other populations and/or from animal research."
Paul Uyehara, whose family operates the Aloha Tofu Factory, said sales are still down 20 percent to 30 percent, despite evidence of healthful benefits of soy products.
"If we were making a dangerous product, obviously I would not want to be any part of it."
Disease study began in 1965White's group began studying diseases and aging in 1965 in 8,006 Japanese-American men on Oahu born 1900 to 1919, volunteers in the Honolulu Heart Program and Honolulu-Asia Aging Study.
Researchers compared the dietary habits and health of 3,734 men in mid-life twice between 1965 and 1993, looking at 27 foods and drinks.
They also performed 290 brain autopsies between February 1992 and January 1999 on participants, identifying four independent indications that eating tofu at mid-life adversely affects brain aging.
Those who ate tofu at least twice a week were more likely to have impaired mental ability, atrophy of the brain and changes in the brain's size and weight at death, the study showed. They also tested as though they were four or five years older. Findings were similar among 500 wives.
"The phenomenon absolutely is not wrong," White said. "It's possible it wasn't really tofu, but it's got to be something tightly related to tofu."
An adverse pharmacological mechanism likely is involved since the effects occurred after eating a "relatively modest" two or more servings a week, the paper says.
Molecules look like estrogenThe obvious candidates, it says, are isoflavones -- molecules made by the soy plant that look like estrogens and affect metabolism of cells.
White said the pharmaceutical industry is "desperately trying to show how good isoflavones are" because of the profits involved. But he said some limited tests are being done "that would get to the adverse effects I'm describing."
He said the TV news program "20-20" has an upcoming show questioning whether the Food and Drug Administration was premature in allowing manufacturers to label soy-based products with a claim that 25 grams or more of soy protein may reduce heart disease.
"They will use a clip of me saying I thought FDA was premature in deciding to do that," White said, noting there has been no research on soy protein and heart disease -- only on cholesterol levels.
Dr. Laurence Kolonel, Cancer Research Center epidemiologist, said he's "somewhat astounded by the amount of publicity this (White's study) is getting.
"A single report like this wouldn't be the basis of getting excited one way or another, even if it showed a positive effect," he said. "At this point, I would hope people wouldn't stop eating tofu, because of other beneficial effects."
Suzanne Murphy, Cancer Research Center nutrition researcher, said the study "is showing associations but we can't really assign cause and effect until there is an actual clinical trial of some kind."
Murphy is involved with a center study headed by Dr. Gertraud Maskarinec to see if eating soy products will lower the risk of breast cancer. They are discussing White's study with participants.
Dr. Brian F. Issell, interim director of the center's prevention and control programs, said the brain-aging study is interesting and should be followed with different kinds of testing.
White said quite a bit of animal research is going on, including a major study by the FDA Intramural Scientific Labs in Arkansas, in which he's involved.
The soy industry is expected to point to health and longevity in Japan's tofu-eating population as a major argument against a Hawaii research study that says tofu may have adverse aging effects.
Soy industry has its arguments
"Would you see it if it was there?" asked Dr. Lon White, who led the Hawaii project. "It would mean people who ate the most tofu all of their lives would be performing as if they were four years older. Could you tell the difference between populations of (age) 80 and 84?"
Without the testing of Japanese-American men participating in the Hawaii study, White said brain impairment probably wouldn't have been noticed except possibly by wives and children.
Soy companies also may claim something other than tofu caused the brain-aging problems identified in the study, White said.
"That's always possible, and a few factors (age, height, years of childhood lived in Japan) were found that were correlated with both tofu intake and cognitive function test scores.
"But the effect of tofu remained apparent after controlling for these, and a diligent search found no other possible confounders," he said.
A third argument he anticipates from the industry is that even if eating tofu were associated with accelerated brain aging, isoflavone phytoestrogens might not be involved.
That is "absolutely true," he said. "The isoflavones are only offered as a possible explanation since a biologic effect of these molecules on the brain with aging appears feasible."
Helen Altonn, Star-Bulletin