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Part 1 of
3 (Part
2, Part
3)
By Mary Enig, PhD, and Sally Fallon
Fats from animal and
vegetable sources provide a concentrated source of energy in the diet; they also provide the
building blocks for cell membranes and a variety of hormones and
hormonelike substances. Fats as part of a meal slow down absorption so
that we can go longer without feeling hungry. In addition, they act as
carriers for important fat-soluble vitamins A, D, E and K. Dietary fats
are needed for the conversion of carotene to vitamin A, for mineral
absorption and for a host of other processes.
Politically Correct Nutrition
is based on the assumption that we should reduce our intake of fats,
particularly saturated fats from animal sources. Fats from animal sources
also contain cholesterol, presented as the twin villain of the civilized
diet.
The
Lipid Hypothesis
The theory-called the lipid
hypothesis-that there is a direct relationship between the amount of
saturated fat and cholesterol in the diet and the incidence of coronary
heart disease was proposed by a researcher named Ancel Keys in the late
1950's. Numerous subsequent studies have questioned his data and
conclusions. Nevertheless, Keys' articles received far more publicity than
those presenting alternate views.
The vegetable oil and food
processing industries, the main beneficiaries of any research that found
fault with competing traditional foods, began promoting and funding
further research designed to support the lipid hypothesis.
The most well-known advocate
of the lowfat diet was Nathan Pritikin. Actually, Pritikin advocated
elimination of sugar, white flour and all processed foods from the diet
and recommended the use of fresh raw foods, whole grains and a strenuous
exercise program; but it was the lowfat aspects of his regime that
received the most attention in the media. Adherents found that they lost
weight and that their blood cholesterol levels and blood pressure
declined.
The success of the Pritikin
diet was probably due to a number of factors having nothing to do with
reduction in dietary fat-weight loss alone, for example, will precipitate
a reduction in blood cholesterol levels-but Pritikin soon found that the
fat-free diet presented many problems, not the least of which was the fact
that people just could not stay on it. Those who possessed enough will
power to remain fat-free for any length of time developed a variety of
health problems including low energy, difficulty in concentration,
depression, weight gain and mineral deficiencies.1
Pritikin may have saved
himself from heart disease but his lowfat diet did not spare him from
cancer. He died, in the prime of life, of suicide when he realized that
his Spartan regime was not curing his leukemia. We shouldn't have to die
of either heart disease or cancer-or consume a diet that makes us
depressed.
When problems with the no-fat
regime became apparent, Pritikin introduced a small amount of fat from
vegetable sources into his diet-something like 10% of the total caloric
intake. Today the Diet Dictocrats advise us to limit fats to 25-30% of the
caloric intake, which is about 2 1/2 ounces or 5 tablespoons per day for a
diet of 2400 calories. A careful reckoning of fat intake and avoidance of
animal fats, they say, is the key to perfect health.
The
"Evidence" Supporting The Lipid Hypothesis
These "experts" assure us
that the lipid hypothesis is backed by incontrovertible scientific proof.
Most people would be surprised to learn that there is, in fact, very
little evidence to support the contention that a diet low in cholesterol
and saturated fat actually reduces death from heart disease or in any way
increases one's life span. Consider the following:
Before 1920 coronary heart
disease was rare in America; so rare that when a young internist named
Paul Dudley White introduced the German electrocardiograph to his
colleagues at Harvard University, they advised him to concentrate on a
more profitable branch of medicine.
The new machine revealed the
presence of arterial blockages, thus permitting early diagnosis of
coronary heart disease. But in those days clogged arteries were a medical
rarity, and White had to search for patients who could benefit from his
new technology. During the next forty years, however, the incidence of
coronary heart disease rose dramatically, so much so that by the mid
fifties heart disease was the leading cause of death among Americans.
Today heart disease causes at
least 40% of all US deaths. If, as we have been told, heart disease
results from the consumption of saturated fats, one would expect to find a
corresponding increase in animal fat in the American diet. Actually, the
reverse is true. During the sixty-year period from 1910 to 1970, the
proportion of traditional animal fat in the American diet declined from
83% to 62%, and butter consumption plummeted from eighteen pounds per
person per year to four.
During the past eighty years,
dietary cholesterol intake has increased only 1%. During the same period
the percentage of dietary vegetable oils in the form of margarine,
shortening and refined oils increased about 400% while the consumption of
sugar and processed foods increased about 60%.2
The Framingham Heart Study is
often cited as proof of the lipid hypothesis. This study began in 1948 and
involved some 6,000 people from the town of Framingham, Massachusetts. Two
groups were compared at five-year intervals-those who consumed little
cholesterol and saturated fat and those who consumed large amounts. After
40 years, the director of this study had to admit:
"In
Framingham, Mass, the more saturated fat one ate, the more cholesterol one
ate, the more calories one ate, the lower the person's serum cholesterol.
. .
We found that the people who
ate the most cholesterol, ate the most saturated fat, ate the most
calories, weighed the least and were the most physically active."3 The
study did show that those who weighed more and had abnormally high blood
cholesterol levels were slightly more at risk for future heart disease;
but weight gain and cholesterol levels had an inverse correlation with fat
and cholesterol intake in the diet.4
In a multi-year British study
involving several thousand men, half were asked to reduce saturated fat
and cholesterol in their diets, to stop smoking and to increase the
amounts of unsaturated oils such as margarine and vegetable oils.
After one year, those on the
"good" diet had 100% more deaths than those on the "bad" diet, in spite of
the fact that those men on the "bad" diet continued to smoke! But in
describing the study, the author ignored these results in favor of the
politically correct conclusion: "The implication for public health policy
in the U.K. is that a preventive program such as we evaluated in this
trial is probably effective. . . ."5
The U.S. Multiple Risk Factor
Intervention Trial, (MRFIT) sponsored by the National Heart, Lung and
Blood Institute, compared mortality rates and eating habits of over 12,000
men. Those with "good" dietary habits (reduced saturated fat and
cholesterol, reduced smoking, etc.) showed a marginal reduction in total
coronary heart disease, but their overall mortality from all causes was
higher.
Similar results have been
obtained in several other studies. The few studies that indicate a
correlation between fat reduction and a decrease in coronary heart disease
mortality also document a concurrent increase in deaths from cancer, brain
hemorrhage, suicide and violent death.6
The Lipid Research Clinics
Coronary Primary Prevention Trial (LRC-CPPT), which cost 150 million
dollars, is the study most often cited by the experts to justify lowfat
diets. Actually, dietary cholesterol and saturated fat were not tested in
this study as all subjects were given a low-cholesterol, low-saturated-fat
diet.
Instead, the study tested the
effects of a cholesterol-lowering drug. Their statistical analysis of the
results implied a 24% reduction in the rate of coronary heart disease in
the group taking the drug compared with the placebo group; however,
nonheart disease deaths in the drug group increased-deaths from cancer,
stroke, violence and suicide.7
Even the conclusion that
lowering cholesterol reduces heart disease is suspect.
Independent researchers who
tabulated the results of this study found no significant statistical
difference in coronary heart disease death rates between the two groups.8
However, both the popular press and medical journals touted the LRC-CPPT
as the long-sought proof that animal fats are the cause of heart disease,
America's number one killer.
Studies That Challenge The Lipid Hypothesis
While it is true that
researchers have induced heart disease in some animals by giving them
extremely large dosages of oxidized or rancid cholesterol-amounts ten
times that found in the ordinary human diet-several population studies
squarely contradict the cholesterol-heart disease connection.
A survey of 1700 patients
with hardening of the arteries, conducted by the famous heart surgeon
Michael DeBakey, found no relationship between the level of cholesterol in
the blood and the incidence of atherosclerosis.9
A survey of South Carolina
adults found no correlation of blood cholesterol levels with "bad" dietary
habits, such as use of red meat, animal fats, fried foods, butter, eggs,
whole milk, bacon, sausage and cheese.10 A Medical Research Council survey
showed that men eating butter ran half the risk of developing heart
disease as those using margarine.11
Mother's milk provides a
higher proportion of cholesterol than almost any other food. It also
contains over 50% of its calories as fat, much of it saturated fat. Both
cholesterol and saturated fat are essential for growth in babies and
children, especially the development of the brain.12 Yet, the American
Heart Association is now recommending a low-cholesterol, lowfat diet for
children! Commercial formulas are low in saturated fats and soy formulas
are devoid of cholesterol. A recent study linked lowfat diets with failure
to thrive in children.13
Numerous surveys of
traditional populations have yielded information that is an embarrassment
to the Diet Dictocrats. For example, a study comparing Jews when they
lived in Yemen, whose diets contained fats solely of animal origin, to
Yemenite Jews living in Israel, whose diets contained margarine and
vegetable oils, revealed little heart disease or diabetes in the former
group but high levels of both diseases in the latter.14 (The study also
noted that the Yemenite Jews consumed no sugar but those in Israel
consumed sugar in amounts equaling 25-30% of total carbohydrate intake.)
A comparison of populations
in northern and southern India revealed a similar pattern. People in
northern India consume 17 times more animal fat but have an incidence of
coronary heart disease seven times lower than people in southern India.15
The Masai and kindred tribes of Africa subsist largely on milk, blood and
beef. They are free from coronary heart disease and have excellent blood
cholesterol levels.16
Eskimos eat liberally of
animal fats from fish and marine animals. On their native diet they are
free of disease and exceptionally hardy.17 An extensive study of diet and
disease patterns in China found that the region in which the populace
consumes large amounts of whole milk had half the rate of heart disease as
several districts in which only small amounts of animal products are
consumed.18
Several Mediterranean
societies have low rates of heart disease even though fat-including highly
saturated fat from lamb, sausage and goat cheese-comprises up to 70% of
their caloric intake. The inhabitants of Crete, for example, are
remarkable for their good health and longevity.19 A study of Puerto Ricans
revealed that, although they consume large amounts of animal fat, they
have a very low incidence of colon and breast cancer.20
A study of the long-lived
inhabitants of Soviet Georgia revealed that those who eat the most fatty
meat live the longest.21 In Okinawa, where the average life span for women
is 84 years-longer than in Japan-the inhabitants eat generous amounts of
pork and seafood and do all their cooking in lard.22 None of these studies
is mentioned by those urging restriction of saturated fats.
The relative good health of
the Japanese, who have the longest life span of any nation in the world,
is generally attributed to a lowfat diet. Although the Japanese eat few
dairy fats, the notion that their diet is low in fat is a myth; rather, it
contains moderate amounts of animal fats from eggs, pork, chicken, beef,
seafood and organ meats. With their fondness for shellfish and fish broth,
eaten on a daily basis, the Japanese probably consume more cholesterol
than most Americans.
What they do not consume is a
lot of vegetable oil, white flour or processed food (although they do eat
white rice.) The life span of the Japanese has increased since World War
II with an increase in animal fat and protein in the diet.23 Those who
point to Japanese statistics to promote the lowfat diet fail to mention
that the Swiss live almost as long on one of the fattiest diets in the
world. Tied for third in the longevity stakes are Austria and Greece-both
with high-fat diets.24
As a final example, let us
consider the French. Anyone who has eaten his way across France has
observed that the French diet is just loaded with saturated fats in the
form of butter, eggs, cheese, cream, liver, meats and rich patés. Yet the
French have a lower rate of coronary heart disease than many other western
countries.
In the United States, 315 of
every 100,000 middle-aged men die of heart attacks each year; in France
the rate is 145 per 100,000. In the Gascony region, where goose and duck
liver form a staple of the diet, this rate is a remarkably low 80 per
100,000.25 This phenomenon has recently gained international attention as
the French Paradox. (The French do suffer from many degenerative diseases,
however. They eat large amounts of sugar and white flour and in recent
years have succumbed to the timesaving temptations of processed foods.)
A chorus of establishment
voices, including the American Cancer Society, the National Cancer
Institute and the Senate Committee on Nutrition and Human Needs, claims
that animal fat is linked not only with heart disease but also with
cancers of various types. Yet when researchers from the University of
Maryland analyzed the data they used to make such claims, they found that
vegetable fat consumption was correlated with cancer and animal fat was
not.26
Understanding The Chemistry Of Fats
Clearly something is wrong
with the theories we read in the popular press-and used to bolster sales
of lowfat concoctions and cholesterol-free foods. The notion that
saturated fats per se cause heart disease as well as cancer is not only
facile, it is just plain wrong. But it is true that some fats are bad for
us. In order to understand which ones, we must know something about the
chemistry of fats.
Fats-or lipids-are a class of
organic substances that are not soluble in water. In simple terms, fatty
acids are chains of carbon atoms with hydrogen atoms filling the available
bonds. Most fat in our bodies and in the food we eat is in the form of
triglycerides, that is, three fatty-acid chains attached to a glycerol
molecule.
levated triglycerides in the
blood have been positively linked to proneness to heart disease, but these
triglycerides do not come directly from dietary fats; they are made in the
liver from any excess sugars that have not been used for energy. The
source of these excess sugars is any food containing carbohydrates,
particularly refined sugar and white flour.
Fatty
Acid Classifications By Saturation
Fatty acids are classified in
the following way:
Saturated:
A fatty acid is saturated when all available carbon bonds are occupied by
a hydrogen atom. They are highly stable, because all the carbon-atom
linkages are filled-or saturated-with hydrogen. This means that they do
not normally go rancid, even when heated for cooking purposes. They are
straight in form and hence pack together easily, so that they form a solid
or semisolid fat at room temperature. Your body makes saturated fatty
acids from carbohydrates and they are found in animal fats and tropical
oils.
Monounsaturated: Monounsaturated fatty acids have one
double bond in the form of two carbon atoms double-bonded to each other
and, therefore, lack two hydrogen atoms. Your body makes monounsaturated
fatty acids from saturated fatty acids and uses them in a number of ways.
Monounsaturated fats have a
kink or bend at the position of the double bond so that they do not pack
together as easily as saturated fats and, therefore, tend to be liquid at
room temperature. Like saturated fats, they are relatively stable. They do
not go rancid easily and hence can be used in cooking. The monounsaturated
fatty acid most commonly found in our food is oleic acid, the main
component of olive oil as well as the oils from almonds, pecans, cashews,
peanuts and avocados.
Polyunsaturated: Polyunsaturated fatty acids have two
or more pairs of double bonds and, therefore, lack four or more hydrogen
atoms. The two polyunsaturated fatty acids found most frequently in our
foods are double unsaturated linoleic acid, with two double bonds-also
called omega-6; and triple unsaturated linolenic acid, with three double
bonds-also called omega-3. (The omega number indicates the position of the
first double bond.)
Your body cannot make these
fatty acids and hence they are called "essential." We must obtain our
essential fatty acids or EFA's from the foods we eat. The polyunsaturated
fatty acids have kinks or turns at the position of the double bond and
hence do not pack together easily. They are liquid, even when
refrigerated.
The unpaired electrons at the
double bonds makes these oils highly reactive.
They go rancid easily,
particularly omega-3 linolenic acid, and must be treated with care.
Polyunsaturated oils should never be heated or used in cooking. In nature,
the polyunsaturated fatty acids are usually found in the cis form, which
means that both hydrogen atoms at the double bond are on the same side.
All fats and oils, whether of
vegetable or animal origin, are some combination of saturated fatty acids,
monounsaturated fatty acids and polyunsaturated linoleic acid and
linolenic acid. In general, animal fats such as butter, lard and tallow
contain about 40-60% saturated fat and are solid at room temperature.
Vegetable oils from northern
climates contain a preponderance of polyunsaturated fatty acids and are
liquid at room temperature. But vegetable oils from the tropics are highly
saturated. Coconut oil, for example, is 92% saturated. These fats are
liquid in the tropics but hard as butter in northern climes. Vegetable
oils are more saturated in hot climates because the increased saturation
helps maintain stiffness in plant leaves. Olive oil with its preponderance
of oleic acid is the product of a temperate climate. It is liquid at warm
temperatures but hardens when refrigerated.
Continued Next
Issue
From: Nourishing Traditions: The Cookbook that Challenges
Politically Correct Nutrition and the Diet Dictocrats by Sally
Fallon with Mary G. Enig, PhD (NewTrends Publishing 2000, http://www.newtrendspublishing.com/ 877-707-1776)
References |