He intermixed his reply with my questions:
Dear Dr. White,
> All of us that follow Dr. D'Adamos diet called "Eat Right 4 Your
> Type" are very interested in you study.
> Is it possible that the tofu eaters ate less animal protein, so were
> deficeint in vitamin B12?
the "high-high" tofu consumers in the cohort were not big
they typically reported 2-3 servings of tofu per week,
and also ate lots of other foods... fish, meat, milk, vegetables, etc.
Given this rather modest level of intake, I have suggested a
pharmacologic mechanism of action. Obviously I have been
the isoflavones as the most likely candidates -- but
that's just because
we know they are pharmacologically active and
occur in non-trivial amts
in soyfoods, and they influence metabolic
systems in ways that might well
be involved in brain function.
It seems unlikely that the relationship
with tofu was really based on a
nutritional deficiency, and I found no relationship of late life
cognitive function or brain weight with frequency of meat
milk consumption, or total
And multivitamin use in another study also seemed unrelated
> Is it possible that the tofu eaters consumed more soy sauce which
> would increase their MSG intake?
they did consume more soy sauce, more rice, ate more fish... but
were not associated with the endpoints once tofu intake was
the analytic model... tofu was much stronger than any
of the other foods
I looked at... if one suspects a constitutent of soy,
then the lack of an effect of soy sauce (one the model had tofu in it)
may just indicate that the quantity of soy constituents consumed
through tofu is greater than in most other foods... similarly, miso
was weakly associated when considered by itself, but became
statistically insignificant when the model considered tofu.
consumption exposure I used occurred here in Hawaii in
the years 1965-67
and 1971-74... I do not believe that the tofu
made and sold here then
usually had either MSG or dyes in it... but I
am not certain about that.
> Do you have ABO blood group data on the subjects?
yes, but haven't looked for an interaction with tofu... but by
ABO types do not correlate with late life cognitive
I do not know of any information that
convincingly supports an interaction
of ABO type with any
environmental factor to influence health in late life.
> I realize that the full study will be published in April, and hope
> that responding to these questions now is appropriate.
unfortunately, the questions you would like to have answered cannot
answered with confidence now. Although the data in my study are
very robust and consistent, we cannot say with total confidence that
they would occur in other times and places and populations. We
cannot be sure that it really was the tofu eating that "caused" the
effects.... and even if it were agreed that it really was something
in the tofu (or intimately correlated with tofu eating) we would not
know what that "something" is. The best we can do now is make
educated guesses and use these to inform the design of additional
The utility of my paper should be that it should stimulate
examine the question, and to raise the question of whether we need
have some reservations about the safety of extreme intake levels of
or the constituents of soyfoods. If other animal and human
consistent and supportive, then some sort of
recommendations would become
reasonable. Until then,
individuals must operate with incomplete and uncertain information...
You pays your money and takes your choice.... I don't not expect
on these questions for 2-6 years.
Sorry I can't be more helpful....