[extropy-chat] Failure of low-fat diet

[Hal Finney]

We probably all saw the study that came out a couple of weeks ago
from the Woman's Health Initiative, which showed that a low-fat diet
failed to offer protection from cancer or heart disease.  This was
a major blow to the conventional wisdom on this issue and there have
been a number of excuses and explanations offered to try to explain the
results.  (At about the same time, a different study found that calcium
supplementation failed to prevent osteoporosis, further contradicting
what public health officials have been saying for years.)

Max More posted a couple of days ago about a business initiative
for "evidence-based" decision-making, attempts to actually measure
decision-making methodologies and see which ones work and which fail.
The article drew an analogy to the new trend in evidence-based medicine.
Unfortunately, as the response to the low-fat result has shown,
evidence-based medicine is still preached more than practiced.  A good
analysis of the situation was in the NY Times yesterday, also available
for non-subscibers at this location:

http://detnews.com/apps/pbcs.dll/article?AID=/20060219/LIFESTYLE03/602190328/1040/LIFESTYLE

The article discusses the long-standing belief in the West that "you
are what you eat" - that it should be possible to become healthy if we
could just find the right diet.  It goes over some of the failed dietary
recommendations of the past, and it talks about the recent fat study.

It's the first article I've seen that lets the people behind the study
respond to their critics.  Other reporting on the issue has been careful
to let the authorities have their say, to make sure that we heard
from defenders of the conventional wisdom eager to deny the evidence.
The women didn't reduce their fat enough, or they reduced the wrong kind
of fat.

According to this Times article, there were good reasons why the study
was set up as it was.  The fat reductions were substantial, and the
prior evidence for a cancer-fat link was total fats, not animal fats.
Researchers point out that if they had just reduced saturated fat and
not found improved health, they would have been lambasted for failing
to reduce total fat intake.

But what I really enjoyed reading were the comments from doctors and
health experts who were truly devoted to the concept of evidence-based
medicine, people who were not so wedded to the preconceived notions that
forced so many others to reject the new results out of hand.  I'll quote
the last few paragraphs of the article:

> Not everyone is attacking the study. Many scientists applaud its findings
> and say it is about time that some cherished dietary notions be put to
> a rigorous test. And some nonscientists are shocked by the reactions of
> the study's critics.
>
> "Whatever is happening to evidence-based treatment?" Dr. Arthur Yeager,
> a retired dentist in Edison, N.J., wrote in an e-mail message. "When
> the facts contravene conventional wisdom, go with the anecdotes?"
>
> The problem, some medical scientists said, is that many people --
> researchers included -- get so wedded to their beliefs about diet and
> disease that they will not accept rigorous evidence that contradicts it.
>
> "Now it's almost a political sort of thing," said Dr. Jules Hirsch,
> physician in chief emeritus at Rockefeller University. "We're all supposed
> to be lean and eat certain things."
>
> And so the notion of a healthful diet, he said, has become more than just
> a question for scientific inquiry. "It is woven into cultural notions of
> ourselves and our behavior," he said. "This is the burden you get going
> into a discussion, and this is why we get so shocked by this evidence."
>
> The truth, said Dr. David Altshuler, an endocrinologist and geneticist
> at Massachusetts General Hospital, is that while the Western diet and
> lifestyle are clearly important risk factors for chronic disease, tweaking
> diet in one way or another -- a bit less fat or a few more vegetables --
> may not, based on studies like the Women's Health Initiative, have major
> effects on health. "We should limit strong advice to where randomized
> trials have proven a benefit of lifestyle modification," Altshuler wrote
> in an e-mail message.
>
> Still, he said, he understands the appeal of dietary prescriptions.
>
> The promise of achieving better health through diet can be so alluring
> that even scientists and statisticians who know all about clinical trial
> data say they sometimes find themselves suspending disbelief when it
> comes to diet and disease.
>
> "I fall for it, too," says Brad Efron, a Stanford statistician. "I really
> don't believe in the low-fat thing, but I find myself doing it anyway."

This is an area where life extension supporters need to be especially
cautious.  There are a great many supplements and nutrients being
advocated by the extension community, where there is no direct evidence
that adding these supplements will improve the situation for healthy
people.  In fact what studies exist have actually shown substantial
toxicity in some of the vitamin cocktails that have been recommended
(primarily due to vitamins A and E).  It is far from clear that most
of these supplements are doing more good than harm.

Many prominent advocates of supplementation are also in the business of
selling them, as well.  You have to be very careful before subjecting
yourself to these regimens.  Skepticism should be the watchword.
Look what happened to the low-fat advocate.  You don't want to end up
like him, with low-cal egg substitute all over his face.

Hal