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4
C ONTR O V E RSIE S
Those Paradoxical French
Gastronomes around the world rejoiced in the early 1990s
when the popular press touted the work of Serge Renaud,
M.D., a scientist at Bordeaux University in France, as a new
reason to hope for better health and longer life. Renaud
and followers noted that the traditional French diet
included lots of saturated fat from butter, foie gras,
cheese, and other delectable sources, yet the French
tended to die much less often from heart disease. The
dogma at the time in cardiology (and still today in some
circles) was that saturated fat causes heart disease, so the
relatively good health of the French people seemed to
pose a paradox.
Scientists cannot abide a paradox, so many focused their
research on uncovering what was keeping the French
healthy. Was it compounds found in red wine? Was it just the
alcohol in wine? Was it the role of “good” fats like olive oil?
Or was it the climate?
Theories multiplied, medical research grants were
awarded, and (not waiting for an answer from science)
diet activists filled books with their own ideas. Among
gastronomes, a lot of red wine consumption was
rationalized as being “good for you.” Indeed, red wine
consumption soared in North America. Life was good.
Unfortunately, subsequent research ended the party when
it settled on two much simpler explanations. The first is that
saturated fat isn’t associated with heart disease anywhere, in
any large study. So it’s not just the French who can eat their
fill of saturated fat without all getting heart disease—people
elsewhere can (and do), too! Indeed, there also seems to be
no link between total fat consumption (excluding trans fat)
and heart disease.
The second part of the solution to the puzzle is equally
mundane: bad statistics. When the World Health Organization
investigated causes of death in France more closely, it found
that the French do actually die of heart disease at about the
same rate as people in neighboring countries.
So the paradox was a big bust—except that it did, in the
end, yield some interesting research. From those studies we
learned that moderate quantities of alcohol do seem to have
a health benefit. Resveratrol, a compound in red wine, may
also have some health benefits, but no compelling results
have emerged from human trials, and animal studies found
benefits only at very high doses. Neither of these findings are
part of the solution to the paradox because the effects of
wine and its compounds are small—and because no paradox
really existed in the first place!
Fat and Heart Disease
Public opinion and the recommendations of most
of the medical profession are very clear: eating
food high in fats is a primary cause of high cholesterol,
which is a primary cause of heart disease. Yet
the latest science shows that links between
cholesterol and heart disease are far more complex
and nuanced. The same can be said for the links
between fats and heart disease.
Speculation about the role of diet in heart
disease has spawned several very different dietary
systems over the years. In one common view, all
fat is bad for you, so a low-fat diet is healthiest.
Others single out saturated fats, trans fats, or both.
Still others praise unsaturated fats such as those in
extra-virgin olive oils and omega-3 oils from
salmon and other cold-water fish.
Yet once again, it has been hard to get reliable,
scientific answers to two basic questions: do
changes in diet change cholesterol levels? And if
they do, do cholesterol levels influence the development
of heart disease? The answers to these two
questions need not be the same.
Fat consumption can indeed have a rapid
effect on HDL and LDL levels in the bloodstream.
This relationship has been confirmed by
many studies, which are relatively easy to do
well because they don’t have to follow people for
many years to get an answer. It is far simpler to
measure cholesterol than it is to actually record
who gets sick.
Even so, the connection between cholesterol in
the food and cholesterol in the blood is muddied
by genetics. People in some families can consume
large amounts of fat without developing high
cholesterol, whereas those in other families have
high cholesterol levels no matter what they eat.
Nevertheless, studies have found that for most
people, the more fat they eat, the higher the total
level of cholesterol (HDL plus LDL) in their blood.
But a puzzle remains: in general, a diet rich in
saturated fats increases HDL more than it increases
LDL. If HDL is “good” cholesterol,
shouldn’t a diet high in saturated fats be protective
against heart disease? That, after all, is the root
idea beneath the belief that unsaturated fats, such
as omega-3 fats or olive oil, have protective
properties. They promote HDL and help prevent
the oxidation of LDL, a reaction that is one of the
steps in the formation of arterial plaques.
Clearly the biology is complicated, so it makes
sense to investigate directly whether fat consumption
affects the incidence of heart disease. Most of
the large, controlled trials of this hypothesis have
concluded that eating fat has no effect, or at most
a small effect (see timeline, next page).
Trials of Dietary Fat and Heart Disease
Three randomized, controlled clinical trials found that eating less total fat or saturated fat for several
years does not lower the incidence of heart disease, stroke, or other cardiovascular diseases.
Study 1: Women’s Health Initiative
Studied outcome: cardiovascular disease,
including heart disease and
stroke
Study duration: about eight years
Intervention group: low-fat diet
Participants: 19,541
Participants with disease: 1,357
(0.9% per year)
Control group: regular diet
Participants: 29,294
Participants with disease: 2,088
(0.9% per year)
Comparative risk: not significantly different
Study 2: Multiple Risk Factor
Intervention Trial
Studied outcome: deaths from heart disease
Study duration: seven years
Intervention group: counseling to reduce
saturated fat and dietary cholesterol
Participants: 6,428
Participants who died: 17.9 per 1,000
Control group: no change in health care
Participants: 6,438
Participants who died: 19.3 per 1,000
Comparative risk: not significantly different
Study 3: Minnesota Coronary
Survey
Studied outcome: heart attack and death
Study duration: one to two years
Intervention group: diet of 18% saturated
fat, high cholesterol
Participants: 4,541
Participants with disease: 131 (2.7% per year)
Control group: diet of 9% saturated fat, low
cholesterol
Participants: 4,516
Participants with disease: 121 (2.6% per year)
Comparative risk: not significantly different
−50% −2%
+50%
−50% −7% +50% −50% +6%
+50%
Lower risk for
intervention group
Equal
risk
Higher risk for
intervention group
(no confidence interval reported)
228 VOLUME 1 · HISTORY AND FUNDAMENTALS
FOOD AND HEALTH 229