How business, doctors and journalists prey on your food anxieties I

Hcalth scare
I
Expect more such nonsense,
because of the inherent
limitarions in the
cpidemiologv of noninfectious
disease . Scientists
could desise an expcriment
that would realk
proNe whethcr loodoses
of secondh<strong>and</strong> smoke
hurt children, but the experimentwould
be unethical
. To really I:now
whether exercise makes
people live longer, c .pcrimenters
would have to
r<strong>and</strong>omly select 1,000
subjects <strong>and</strong> regiment
their evero waking moment
for decades .
In default of such serious
studies, distrust most
sweeping conclusions
linking diet <strong>and</strong> health .
Yes, cou can proN e statisticallv
that people who esercise Gve longer . But the corv.dusion-that
exercise is good for you-mav put tJte cart
before the horse . Think about it . Are people healdty
because tluv esercisei Or do thev exercise because they arc
healthv? The barc correlation proves nothing . Pltysiological
<strong>and</strong> other e\ ;dence leads mariv <strong>doctors</strong> to conclude
exercise helps . But even here, there's no clear proof
The mass media punev health scare stories breath-
!ess[v, treating each new paper in isolation t}om the ones
that came betixe . E%en if the researchers concede that
there are limitations to the validity of the study, the media
usuallv bury the caveat . "You reporters take at face value
eVerything the scientists tell vou-something y'ou would
ne~er think of doing if the
source «-ere industrv
or the government,"
grouses one prominent
cpidemiologist .
There's too much at
stake for the health scare
industry to admit to the
shortcomings ofepidemiology
. The Berkeley, Har-
% ard, Johns Hopkins,
Tutis <strong>and</strong> L'niversit • of
Texas medical schools are
raising monev by publishing
health tip nct%,slettcrs
for the general puhlic-
The Journal of the American
Medical Association
takes in S1, million in
adsetZising a aenr . Jane
Br ndv's Good Fod Book :
Lirialt the HiAh Crtr6oht .-
drnte SVav( 1985 ) is in its
tenth printing . Sales of
preparcd fr>ods ntaking
health claims ("lo%c-tat,"
"no sugar added," '9o r
sodium") account ;or
S23 billion a vear .
Let's go back to the
butter/margarine argumcnt.
In 1993 a group at
Harvard linked trans-fatty
acids to heart disease,
adding, a year latcr, that
the synthetic fats may be
responsible for an estra
30,000 deaths a vear in
the U .S . Margarine, of
course, is fu':l of regetable
oil hardened by a process
called hydrogemationtishich
produces trans-fat-
R, acids . The next year,
murgarine sales dropped
8 .2% by volumc, <strong>and</strong> butter
sales rose 1-4% .
Take eggs. "You'd
think there were half a dozen studies saring to avoid eggs ; "
sa~s Walter C Willett of the Han, ard School oF Public
Health . "Guess how manv there n°erc? When we started
looking at this question, zero . Now there's still ven little
information . No one's cven slto~~n it in ut observational
study [one where eou compare people who say they cat
eggs with people who sac they don't] . The recommendation
was based only on reasoning that cholesterol in diet
affects blood cholesterol, <strong>and</strong> that eggs havc cholesterol ."
Tell that to the chicken farmers . Thcr've watched dtolesterol-spooked
consumers cut their egg consumption from
a pc-ik of 402 eggs per capita in 1945 to 238 todac .
The old eggs-are-bad theory was built on a pretty sseak
connection, that cholesterol
in foods affects
blood cholesterol . But the
fact is that gcnctic ntakeup
is far more important
than consumption ofcholesterol
in determining
blood cholesterol Ieels .
Mavncltile, millions of
children who could benetit
from the cheap protein
in eggs are being shooed
awav troni it .
Then there's the outrageous
canipaign against
"passivc" smoking . Some
stndies 11,10 e purported to
show that people exposed
to other pcoplc's smokc
arc more prone to lung
caneer than the general
population . The statistics
are dubious . So-called
passi~e smokers often
1?2
Porues . Au,ua 14 . 1995
http://legacy.library.ucsf.edu/tid/agf97d00/pdf