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By Mary Enig and Sally Fallon
Modern-day diets high in hydrogenated
vegetable oils instead of traditional animal fats are implicated
in causing a significant increase in heart disease and cancer.
In 1954 a young researcher from Russia,
named David Kritchevsky, published a paper describing the
effects of feeding cholesterol to rabbits.1 Cholesterol added
to vegetarian rabbit chow caused the formation of atheromas
- plaques that block arteries and contribute to heart disease.
Cholesterol is a heavyweight molecule - an alcohol or a sterol
- found only in animal foods such as meat, cheese, eggs and
In the same year, according to the American
Oil Chemists Society, Kritchevsky published a paper describing
the beneficial effects of
polyunsaturated fatty acids for lowering cholesterol
levels.2 (Polyunsaturated fatty acids are the kind of fats
found in large amounts in highly liquid vegetable oils made
from corn, soybeans, safflower seeds and sunflower seeds.
Mono-unsaturated fatty acids are found
in large amounts in olive oil, palm oil and lard; saturated
fatty acids are found in large amounts in fats and oils that
are solid at room temperature, e.g., butter, tallow and coconut
Scientists of the period were grappling
with a new threat to public health: a steep rise in heart
disease. While turn-of-the-century mortality statistics are
unreliable, they consistently indicate that heart disease
caused no more than 10 per cent of all deaths - considerably
less than infectious diseases such as pneumonia and tuberculosis.
By 1950, coronary heart disease (CHD) was the leading source
of mortality in the United States, causing more than 30 per
cent of all deaths.
The greatest increase came under the rubric
of myocardial infarction (MI) - a massive blood clot leading
to obstruction of a coronary artery and consequent death to
the heart muscle. MI was almost non-existent in 1910 and caused
no more than 3,000 deaths per year in 1930. By 1960, there
were at least 500,000 MI deaths per year in the US. What lifestyle
changes had caused this increase?
One change was a decrease in infectious
disease, following the decline of the horse as a means of
transport, the installation of more sanitary water supplies
and the advent of better housing, all of which allowed more
people to reach adulthood and the heart attack age. The other
was a dietary change.
Since the early part of the century when
the US Department of Agriculture (USDA) had begun to keep
track of food 'disappearance' data (the amount of various
foods going into the food supply), a number of researchers
had noticed a change in the kind of fats Americans were eating.
Butter consumption was declining, while
the use of vegetable oils, especially oils that had been hardened
to resemble butter by a process called 'hydrogenation', was
By 1950, butter consumption had dropped
from 18 pounds per person per year to just over 10 pounds.
Margarine filled in the gap, rising from about two pounds
per person at the turn of the century to about eight. Consumption
of vegetable shortening - used in crackers and baked goods
- remained relatively steady at about 12 pounds per person
per year, but vegetable oil consumption had more than tripled
from just under three pounds per person per year to more than
The statistics pointed to one obvious
conclusion: Americans should eat the traditional foods - including
meat, eggs, butter and cheese - that nourished their ancestors,
and avoid the newfangled, vegetable-oil-based foods that were
flooding the grocers' shelves.
The Kritchevsky articles attracted immediate
attention because they lent support to another theory - one
that militated against the consumption of meat and dairy products.
This was the lipid hypothesis: namely,
that saturated fat and cholesterol
from animal sources raise cholesterol levels in the blood,
leading to deposition of cholesterol and fatty material as
pathogenic plaques in the arteries.
Kritchevsky's rabbit trials were actually
a repeat of studies carried out four decades earlier in St
Petersburg, in which rabbits fed saturated fats and cholesterol
developed fatty deposits in their skin and other tissues -
and in their arteries.
By showing that polyunsaturated oils from
vegetable sources lowered
serum cholesterol at least temporarily in humans,
Kritchevsky appeared to show that the findings from the animal
trials were relevant to the CHD problem, that the lipid hypothesis
was a valid explanation for the new epidemic, and that, by
reducing animal products in their diets, Americans could avoid
In the years that followed, a number of
population studies demonstrated that the animal model - especially
one derived from vegetarian animals - was not a valid approach
for the problem of heart disease in human omnivores.
report on artery plaques in soldiers killed during the Korean
War showed little difference in the number and severity of
plaques between American soldiers and those of Japanese natives
- 75 per cent versus 65 per cent - even though the Japanese
diet at the time was lower in animal products and fat.4
study of the largely vegetarian Bantu found that they had
as much atheroma - occlusions or plaque build-up in the arteries
- as other races from South Africa who ate more meat.5
report noted that Jamaican Blacks showed a degree of atherosclerosis
comparable to that found in the United States, although they
suffered from lower rates of heart disease.6
report noted that the severity of atherosclerotic lesions
in Japan approached that of the United States.7
The 1968 International Atherosclerosis
Project, in which over 22,000 corpses in 14 nations were cut
open and examined for plaques in the arteries, showed the
same degree of atheroma in all parts of the world - in populations
that suffered from a great deal of heart disease, and in populations
that had very little or none at all.8
All of these studies pointed to the fact
that the thickening of the arterial walls is a natural, unavoidable
process. The lipid hypothesis did not hold up to these population
studies, nor did it explain the tendency toward fatal clots
that caused myocardial infarction.
In 1956, an American Heart Association
(AHA) fund-raiser was aired on all three major networks. The
Master of Ceremonies interviewed, among others, Irving Page
and Jeremiah Stamler of the AHA and researcher Ancel Keys.
Panellists presented the lipid hypothesis
as the cause of the heart disease epidemic and launched the
Prudent Diet, one in which corn oil, margarine, chicken and
cold cereal replaced butter, lard, beef and eggs.
The television campaign was not an unqualified
success because one of the panellists, Dr Dudley White, disputed
his colleagues at the AHA. Dr White noted that heart disease
in the form of myocardial infarction was non-existent in 1900
when egg consumption was three times what it was in 1956 and
when corn oil was unavailable.
When pressed to support the Prudent Diet,
Dr White replied:
"See here, I
began my practice as a cardiologist in 1921 and I never
saw an MI patent until 1928. Back in the MI-free days before
1920 the fats were butter and lard, and I think that we
would all benefit from the kind of diet that we had at a
time when no one had ever heard the word 'corn' oil."
But the lipid hypothesis had already gained
enough momentum to keep it rolling, in spite of Dr White's
nationally televised plea for common sense in matters of diet
and in spite of the contradictory studies that were showing
up in the scientific literature.
In 1957, Dr Norman Jolliffe, Director
of the Nutrition Bureau of the New York Health Department,
initiated the Anti-Coronary Club in which selected businessmen,
ranging in age from 40 to 59 years, were placed on the Prudent
Diet. Club members used corn oil and margarine instead of
butter, cold breakfast cereals instead of eggs and chicken,
and fish instead of beef.
Anti-Coronary Club members were to be
compared with a 'matched' group of the same age who ate eggs
for breakfast and had meat three times a day. Jolliffe, an
overweight diabetic confined to a wheelchair, was confident
that the Prudent Diet would save lives, including his own.
In the same year, the food industry initiated
advertising campaigns that touted the health benefits of their
products: low in fat or made with vegetable oils. A typical
ad read "Wheaties may help you live longer". Wesson
recommended its cooking oil "for your heart's sake".
An ad in the Journal of the American Medical
Association (JAMA) described Wesson oil as a "cholesterol
depressant". Mazola advertisements assured the public
that "science finds corn oil important to your health".
Medical journal ads recommended Fleishmann's unsalted margarine
for patients with high blood pressure.
In his syndicated column, Dr Frederick
Stare, head of Harvard University's Nutrition Department,
encouraged the consumption of corn oil - up to one cup a day.
In a promotional piece specifically for Proctor and Gamble's
Puritan oil, he cited two experiments and one clinical trial
as showing that high blood cholesterol is associated with
However, both experiments had nothing
to do with CHD, and the clinical trial did not find that reducing
blood cholesterol had any effect on CHD events. Later, Dr
William Castelli, director of the Framingham Study, was one
of several specialists to endorse Puritan. Dr Antonio Gotto,
Jr, former AHA president, sent practising physicians a letter
promoting Puritan oil - printed on Baylor College of Medicine,
The De Bakey Heart Center letterhead.9
The irony of Gotto's letter is that De
Bakey, the famous heart surgeon, co-authored a 1964 study
involving 1,700 patients, which also showed no definite correlation
between serum cholesterol levels and the nature and extent
of coronary artery disease.10 In other words, those with low
cholesterol levels were just as likely to have blocked arteries
as those with high cholesterol levels.
But while studies like DeBakey's mouldered
in the basements of university libraries, the vegetable oil
campaign took on increased bravado and audacity.
The American Medical Association (AMA)
at first opposed the commercialisation of the lipid hypothesis
and warned that "the anti-fat, anti-cholesterol fad is
not just foolish and futile...it also carries some risk".
The American Heart Association, however,
was committed. In 1961, the AHA published its first dietary
guidelines aimed at the public. The authors, Irving Page,
Ancel Keys, Jeremiah Stamler and Frederick Stare, called for
the substitution of polyunsaturates for saturated fat, even
though Keys, Stare and Page had all previously noted in published
papers that the increase in CHD was paralleled by increasing
consumption of vegetable oils. In fact, in a 1956 paper, Keys
had suggested that the increasing use of hydrogenated vegetable
oils might be the underlying cause of the CHD epidemic.11
Stamler showed up again in 1966 as an
author of Your Heart Has Nine Lives, a little self-help book
advocating the substitution of vegetable oils for butter and
other so-called 'artery-clogging' saturated fats.
The book was sponsored by makers of Mazola
corn oil and Mazola margarine.
Stamler did not believe that lack of evidence
should deter Americans from changing their eating habits.
The evidence, he stated, was "...compelling enough to
call for altering some habits even before the final proof
is nailed down... the definitive proof that middle-aged men
who reduce their blood cholesterol will actually have far
fewer heart attacks waits upon diet studies now in progress."
His version of the Prudent Diet called
for substituting low-fat milk products such as skim milk and
low-fat cheeses for cream, butter and whole cheeses, reducing
egg consumption and cutting the fat off red meats. Heart disease,
he lectured, was a disease of rich countries, striking rich
people who ate rich food, including 'hard' fats like butter.
It was in the same year, 1966, that the
results of Dr Jolliffe's Anti-Coronary Club experiment were
published in JAMA.12 Those on the Prudent Diet of corn oil,
margarine, fish, chicken and cold cereal had an average serum
cholesterol of 220, compared to 250 in the meat-and-potatoes
However, the study authors were obliged
to note that there were eight deaths from heart disease among
Dr Jolliffe's Prudent Diet group, and none among those who
ate meat three times a day. Dr Jolliffe was dead by this time.
He succumbed in 1961 from a vascular thrombosis, although
the obituaries listed the cause of death as "complications
"proof" that Stamler and others were sure would
vindicate wholesale tampering with American eating habits
had not yet been "nailed down".
The problem, said the insiders promoting
the lipid hypothesis, was that the numbers involved in the
Anti-Coronary Club experiment were too small. Dr Irving Page
urged a National Diet-Heart Study involving one million men,
in which the results of the Prudent Diet could be compared
on a large scale with those on a diet high in meat and fat.
With great media attention, the National
Heart, Lung and Blood Institute organised the stocking of
food warehouses in six major cities, where men on the Prudent
Diet could get tasty polyunsaturated doughnuts and other fabricated
food items free of charge.
But a pilot study, involving 2,000 men,
resulted in exactly the same number of deaths in both the
Prudent Diet group and the control group. A brief report in
Circulation (March 1968) stated that the study was a milestone
"in mass environmental experimentation" that would
have "an important effect on the food industry and the
attitude of the public toward its eating habits".
But the million-man Diet-Heart Study was
abandoned in utter silence "for reasons of cost".
Its chairman, Dr Irving Page, died of a heart attack.
Most animal fats - like butter, lard and
tallow - have a large proportion of saturated fatty acids.
Saturated fats are straight chains of carbon and hydrogen
that pack together easily so that they are relatively solid
at room temperature. Oils from seeds are composed mostly of
polyunsaturated fatty acids.
These molecules have kinks in them at
the point of the unsaturated double bond. They do
not pack together easily and therefore tend to
be liquid at room temperature.
Judging from both food data and turn-of-the-century
cookbooks, the American diet in 1900 was a rich one, with
at least 35 to 40 per cent of calories coming from fats, mostly
dairy fats in the form of butter, cream, whole milk, and also
eggs. Salad dressing recipes usually called for egg yolks
or cream; only occasionally for olive oil. Lard or tallow
served for frying.
Rich dishes like head cheese and scrapple
contributed additional saturated fats during an era when cancer
and heart disease were rare. Butter substitutes made up only
a small portion of the American diet, and these margarines
were blended from coconut oil, animal tallow and lard - all
rich in natural saturates.
The technology by which liquid vegetable
oils could be hardened to make margarine was first discovered
by a French chemist named Sabatier. He found that a nickel
catalyst would cause the hydrogenation (the addition of hydrogen
to unsaturated bonds to make them saturated) of ethylene gas
Subsequently, the British chemist Norman
developed the first application of hydrogenation to food oils
and took out a patent. In 1909, Procter & Gamble acquired
the US rights to a British patent on making liquid vegetable
oils solid at room temperature.
The process was used on both cotton-seed
oil and lard to give "better physical properties",
to create shortenings that did not melt as easily on hot days.
The hydrogenation process transforms unsaturated
oils into straight 'packable' molecules by rearranging the
hydrogen atoms at the double bonds. In nature, most double
bonds occur in the cis configuration - that is, with both
hydrogen atoms on the same side of the carbon chain at the
point of the double bond. It is the cis isomers of fatty acids
that have a bend or kink at the double bond, preventing them
from packing together easily.
Hydrogenation creates trans double bonds
by moving one hydrogen atom across to the other side of the
carbon chain at the point of the double bond. In effect, the
two hydrogen atoms then balance each other and the fatty acid
straightens, creating a packable 'plastic' fat with a much
higher melting temperature.
Although trans fatty acids are technically
unsaturated, they are configured in such a way that the benefits
of unsaturation are lost. The presence of several unpaired
electrons presented by contiguous hydrogen atoms in their
cis form allows many vital chemical reactions to occur at
the site of the double bond.
When one hydrogen atom is moved to the
other side of the fatty acid molecule during hydrogenation,
the ability of living cells to make reactions at the site
is compromised or altogether lost. Trans fatty acids are sufficiently
similar to natural fats that the body readily incorporates
them into the cell membrane; once there, their altered chemical
structure creates havoc with thousands of necessary chemical
reactions - everything from energy provision to prostaglandin
After the Second World War, 'improvements'
made it possible to plasticise highly unsaturated oils from
corn and soybeans. New catalysts allowed processors to 'selectively
hydrogenate' the kinds of fatty acids found in soy and canola
oils - those with three double bonds.
Called 'partial hydrogenation', this new
method allowed processors to replace cotton-seed oil with
more unsaturated corn and soybean oils in margarines and shortenings.
This spurred a meteoric rise in soybean production from virtually
nothing in 1900 to 70 million tons in 1970, surpassing corn
production. Today, soy oil dominates the market and is used
in almost 80 per cent of all hydrogenated oils.
The particular mix of fatty acids in soy
oil results in shortenings containing about 40 per cent trans
fats - an increase of about 5 per cent over cotton-seed oil
and 15 per cent over corn oil. Canola oil, processed from
a hybrid form of rape-seed, is particularly rich in fatty
acids containing three double bonds and can contain as much
as 50 per cent trans fats.
Trans fats of a particularly problematic
type are also formed during the process of deodorising canola
oil, although they are not indicated on labels for canola
Certain forms of trans fatty acids occur
naturally in dairy fats. Trans vaccenic acid makes up about
four per cent of the fatty acids in butter. It is an interim
product which the ruminant animal then converts to conjugated
linoleic acid, a highly beneficial anti-carcinogenic component
of animal fat. Humans seem to utilise the small amounts of
trans vaccenic acid in butter fat without ill effects.
However, most of the trans isomers in
modern hydrogenated fats are new to the human physiology.
By the early 1970s, a number of researchers had expressed
concern about their presence in the American diet, noting
that the increasing use of hydrogenated fats had paralleled
the increase in both heart disease and cancer.
The unstated solution was one that could
be easily presented to the public: eat natural, traditional
fats; avoid newfangled foods made from vegetable oils; use
butter, not margarine.
But medical research and public consciousness
took a different tack - one that accelerated the decline of
traditional foods like meat, eggs and butter, and fuelled
continued dramatic increases in vegetable oil consumption.
Although the AHA had committed itself
to the lipid hypothesis and the unproven theory that polyunsaturated
oils afforded protection against heart disease, concerns about
hydrogenated vegetable oils were sufficiently great to warrant
the inclusion of the following statement in the organisation's
1968 diet heart statement: "Partial hydrogenation of
polyunsaturated fats results in the formation of trans forms
which are less effective than cis, cis forms in lowering cholesterol
It should be noted that many currently
available shortenings and margarines are partially hydrogenated
and may contain little polyunsaturated fat of the natural
cis, cis form."
While 150,000 copies of the statement
were printed, they were never distributed. The shortening
industry objected strongly, and a researcher named Fred Mattson
of Procter & Gamble convinced Campbell Moses, medical
director of the AHA, to remove it.13 The final recommendations
for the public contained three major points:
polyunsaturates for saturates
cholesterol in the diet
Other organisations fell in behind the
AHA in pushing vegetable oils instead of animal fats. By the
early 1970s, the National Heart, Lung and Blood Institute,
the AMA, the American Dietetic Association and the National
Academy of Sciences had all endorsed the lipid hypothesis
and the avoidance of animal fats for those Americans in the
'at risk' category.
Since Kritchevsky's early studies, many
other trials had shown that serum cholesterol can be lowered
by increasing ingestion of polyunsaturates. The physiological
explanation for this is that when excess polyunsaturates are
built into the cell membranes, resulting in reduced structural
integrity or 'limpness', cholesterol is sequestered from the
blood into the cell membranes to give them 'stiffness'.
The problem was that there was no
proof that lowering serum cholesterol levels could
stave off CHD.