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How do We Know Fat's a Problem?
by Eleanor Mayfield
 In
1908, scientists first observed that rabbits fed a diet
of meat, whole milk, and eggs developed fatty deposits
on the walls of their arteries that constricted the flow
of blood.
Narrowing of the arteries by these fatty deposits
is called atherosclerosis. It is a slowly progressing disease that
can begin early in life but not show symptoms for many years. In 1913,
scientists identified the substance responsible for the fatty deposits
in the rabbits' arteries as cholesterol.
In 1916, Cornelius de Langen, a Dutch physician working in Java,
Indonesia, noticed that native Indonesians had much lower
rates of heart disease than Dutch colonists living on the
island. He reported this finding to a medical journal, speculating
that the Indonesians' healthy hearts were linked with their
low levels of blood cholesterol.
De Langen also noticed that both blood cholesterol levels
and rates of heart disease soared among Indonesians who abandoned
their native diet of mostly plant foods and ate a typical
Dutch diet containing a lot of meat and dairy products. This
was the first recorded suggestion that diet, cholesterol levels,
and heart disease were related in humans. But de Langen's
observations lay unnoticed in an obscure medical journal for
more than 40 years.
After World War II, medical researchers in Scandinavia noticed
that deaths from heart disease had declined dramatically during
the war, when food was rationed and meat, dairy products,
and eggs were scarce. At about the same time, other researchers
found that people who suffered heart attacks had higher levels
of blood cholesterol than people who did not have heart attacks.
Since then, a large body of scientific evidence has been
gathered linking high blood cholesterol and a diet high in
animal fats with an elevated risk of heart attack. In countries
where the average person's blood cholesterol level is less
than 180 mg/dl, very few people develop atherosclerosis or
have heart attacks. In many countries where a lot of people
have blood cholesterol levels above 220 mg/dl, such as the
United States, heart disease is the leading cause of death.
High rates of heart disease are commonly found in countries
where the diet is heavy with meat and dairy products containing
a lot of saturated fats. However, high-fat diets and high
rates of heart disease don't inevitably go hand-in-hand.
Learning from Other Cultures
People living on the Greek island of Crete have very low
rates of heart disease even though their diet is high in fat.
Most of their dietary fat comes from olive oil, a monounsaturated
fat that tends to lower levels of "bad" LDL-cholesterol and
maintain levels of "good" HDL-cholesterol.
The Inuit, or Eskimo, people of Alaska and
Greenland also are relatively free of heart disease despite a high-fat,
high-cholesterol diet. The staple food in their diet is fish rich
in omega-3 polyunsaturated fatty acids.
Some research has shown that omega-3 fatty acids, found in fish such
as salmon and mackerel as well as in soybean and canola oil,
lower both LDL-cholesterol and triglyceride levels in the
blood. Some nutrition experts recommend eating fish once or
twice a week to reduce heart disease risk. However, dietary
supplements containing concentrated fish oil are not recommended
because there is insufficient evidence that they are beneficial
and little is known about their long-term effects.
Omega-6 polyunsaturated fatty acids have also been found
in some studies to reduce both LDL- and HDL-cholesterol levels
in the blood. Linoleic acid, an essential nutrient (one that
the body cannot make for itself) and a component of corn,
soybean and safflower oil, is an omega-6 fatty acid.
At one time, many nutrition experts recommended increasing
consumption of monounsaturated and polyunsaturated fats because
of their cholesterol-lowering effects. Now, however, the advice
is simply to reduce dietary intake of all types of fat. (Infants
and young children, however, should not restrict dietary fat.)
The available information on fats may be voluminous and is
sometimes confusing. But sorting through the information becomes
easier once you know the terms and some of the history.
The "bottom line" is actually quite simple, according to
John E. Vanderveen, Ph.D., director of the Office of Plant
and Dairy Foods and Beverages in FDA's Center for Food Safety
and Applied Nutrition. "What we should be doing is removing
as much of the saturated fat from our diet as we can. We need
to select foods that are lower in total fat and especially
in saturated fat." In a nutshell, that means eating fewer
foods of animal origin, such as meat and whole-milk dairy
products, and more plant foods such as vegetables and grains.
Eleanor Mayfield is a writer in Silver
Spring, Md.
Food and Drug Administration
Publication No. (FDA) 99-2286
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