Up to the 19th-century, fat was relatively
expensive and butter was a luxury. The poor lived mainly on potatoes and bread,
which were cheap, supplemented whenever possible with whatever source of protein
and fat they could afford. Not surprisingly, mortality was high amongst the
poorer classes. To fill the gap in the market cheap substitutes for butter began
to be produced in the last quarter of the Victorian era. Made from cheaper fats
and coloured yellow to mimic the look, if not the taste of butter, they were
called margarine. And this started, quite slowly at first, a radical change in
the types of fat we, as a nation, ate.
Originally margarines were made of beef suet,
milk and water. Later the recipes changed to include lard, whale oil and the
oils of olive, coconut, ground nut and cottonseed. By the middle of the
20th-century an emulsion of soya bean and water was substituted for the milk and
margarines could be made entirely of inexpensive oils from vegetable sources. In
all these forms, margarine was the poor relation to butter.
In the 1920s a new disease had suddenly 'taken
off' all over the industrialised world. By the 1940s it had become a leading
cause of premature death – and nobody knew why. In 1950, an American
scientists hypothesised that cholesterol might be to blame. (1)
In 1953, another American, Ancel Keys, compared levels of this disease in seven
countries with the amounts of fat in those countries. (2)
And so was born the 'Diet-Heart' hypothesis, for the new disease was coronary
To reduce the risk of a heart attack, Ancel Keys
recommended cutting down on the vegetable oils and margarines. However, it was
discovered that vegetable oils, which are composed largely of unsaturated fats
and oils, tended to lower blood cholesterol levels, while saturated fats tended
to raise them. And by that time, it had been decided, largely by majority vote, (3)
that raised cholesterol increased the risk of a heart attack. With the advent of
the 'Prudent Diet' in the USA in 1982, and COMA's introduction of 'healthy
eating' in Britain two years later, the fats in our diet changed even more
dramatically: we were told to avoid animal fats such as butter and lard, which
have a larger proportion of saturated fats, in favour of largely polyunsaturated
vegetable margarines and cooking oils. Now margarines could be priced to rival
butter. Recently, margarines have been developed specifically to lower
cholesterol levels, and prices have risen again. Benecol, made from tree bark is
considerably more expensive than butter.
going further, it might be as well for you to learn a little chemistry. This
will make understanding how the different fats react under different
circumstances. This is essential to understanding how cancers start or are
Margarine – a natural food?
The polyunsaturated fats used to make margarine
are generally obtained from vegetable sources: sunflower seed, cottonseed, and
soybean. As such they might be thought of as natural foods. Usually, however,
they are pressed on the public in the form of highly processed margarines,
spreads and oils and, as such, they are anything but natural.
In 1989, the petroleum-based solvent, benzene,
that is known to cause cancer, was found in Perrier mineral water at a mean
concentration of fourteen parts per billion. This was enough to cause Perrier to
be removed from supermarket shelves. The first process in the manufacture of
margarine is the extraction of the oils from the seeds, and this is usually done
using similar petroleum-based solvents. Although these are then boiled off, this
stage of the process still leaves about ten parts per million of the solvents in
the product. That is 700 times as much as fourteen parts per billion.
The oils then go through more than ten other
processes: degumming, bleaching, hydrogenation, neutralization, fractionation,
deodorisation, emulsification, interesterification, . . . that include heat
treatment at 140-160C with a solution of caustic soda; the use of nickel, a
metal that is known to cause cancer, as a catalyst, with up to fifty parts per
million of the nickel left in the product; the addition of antioxidants such as
butylated hydroxyanisol (E320). These antioxidants are again usually petroleum
based and are widely believed to cause cancer.
The hydrogenation process, that solidifies the
oils so that they are spreadable, produces trans -fatty acids that
rarely occur in nature.
The heat treatment alone is enough to render
these margarines nutritionally inadequate. When the massive chemical treatment
and unnatural fats are added, the end product can hardly be called either
natural or healthy.
You may be interested in a list of the
ingredients that may be present in butter and margarine:
milk fat (cream),
a little salt,
salt or potassium chloride,
mono- and di-glycerides of fat-forming fatty acids,
diacetyltartaric and fatty acid esters of glycerol,
Propyl, octyl or dodecyl gallate (or mixtures thereof),
propylene glycol mono- and di-esters,
sucrose esters of fatty acids,
ß-apo-carotenoic acid methyl or ethyl ester,
skim milk powder,
vitamins A and D.
Dietary fat patterns
The total amount of fats in our diet today,
according to the MAFF National Food Survey, is almost the same as it was at the
beginning of this century. What has changed, to some extent, is the types of
fats eaten. At the turn of the century we ate mainly animal fats that are
largely saturated and monounsaturated. Now we are tending to eat more
polyunsaturated fats – it's what we are advised to do. In 1991, two studies,
from USA (4)
and Canada, (5)
found that linoleic acid, the major polyunsaturated fatty acid found in
vegetable oils, increased the risk of breast tumours. This, it seems, was
responsible for the rise in the cancers noted in previous studies. Experiments
with a variety of fats showed that saturated fats did not cause tumours but,
when small amounts of polyunsaturated vegetable oil or linoleic acid itself was
added, this greatly increased the promotion of breast cancer.
Body cell walls are made of cholesterol, protein
and fats. The graph below demonstrates that the human body's fat make-up is
largely of saturated and monounsaturated fatty acids. We contain very little
polyunsaturated fat. Cell walls have to allow the various nutrients that body
cells need from the blood, but stop harmful pathogens. They must be stable. An
intake of large quantities of polyunsaturated fatty acids changes the
constituency of cholesterol and body fat. Cell walls become softer and more
Polyunsaturated fats suppress the
Polyunsaturated fats (PUFs) are greatly
immunosuppressive, and anything that suppresses the immune system is likely to
cause cancer. The first person to suggest that polyunsaturated fats cause cancer
was Dr R A Newsholme of Oxford University, England. (6)
What Newsholme wrote was that when our bodies get sufficient nutrition, our diet
includes immunosuppressive PUFs which make us prone to infection by bacteria and
viruses. When we are starved, however, our body stores of PUFs are depleted.
This allows our bodies' immune systems to recover which, in turn, allows us to
fight existing infection and prevent other infections. He was making the point
that the immunosuppressive effects of PUFs in sunflower seeds are useful in
treating autoimmune diseases such as multiple sclerosis, (7)
and that the same fatty acids could be used to suppress the immune system to
prevent rejection of kidney transplants.
It was during the early days of kidney
transplantation that doctors first encountered the problem of tissue rejection
as their patients' bodies destroyed the alien transplanted kidneys. If
transplantation were to be a success, they had to find a way to suppress the
immune system. Newsholme had said that there was no better way to immunosuppress
a renal patient than with sunflower seed oil. So kidney transplant doctors fed
their patients linoleic acid. (8)
(Linoleic acid is the major polyunsaturated fatty acid in vegetable oils.) But
the transplant doctors were then astonished to see how quickly their patients
developed cancers: some cancers were up to twenty times as frequent as was
This was in line with heart trials using diets
that were high in PUFs which, reported an excess of cancer deaths from as early
as 1971. (9)
By the early 1980s, we were being exhorted by
doctors and nutritionists to eat more PUFs because they were 'good for us'
despite the fact that Oncology Times carried a paper in January 1980
from the University of California at Davis that mice fet PUFs were more prone to
develop melanoma. In May 1980, the same publication carried a similar report
from Oregon State University which said that PUFs fed to cancer-prone mice
increased the numbers of cancers formed.
In 1989 there was a report of a ten-year trial
at a Veterans' Administration Hospital in Los Angeles. In this trial half the
patients were fed a diet which had double the amount of PUFs as compared to
saturated fats. In the half of the patients on the high PUF diet there was a
fifteen percent increase in cancer deaths compared to the saturated fat group. (10)
The authors of the report said that the PUFs had been the cause of the increase
in cancer deaths. The British Medical Journal carried an editorial in
its 6 October 1973 issue which asked if PUFs were carcinogenic. It came to the
conclusion that they were.
Wayne Martin likes to tell a story which
suggests just how cancer-causing are PUFs. In 1930 in the USA, eighty percent of
men smoked cigarettes and the tar content of cigarettes was much higher than it
is today. The death rate at that time from lung cancer was very low. In 1955
doctors decided that PUFs were good in terms of heart disease protection. After
this lung cancer deaths increased so dramatically. By 1980 although the number
of American men who smoked had dropped to only thirty percent, three times as
much PUF was being eaten – and there were sixty times as many lung cancer
In 1990, Martin called Newsholme's Oxford
University office but by then Newsholme had retired. Martin spoke to his
successor to find that they were still treating autoimmune diseases with PUFs.
By then they were using fish oil. The doctor said the reason for the fish oil
was that the degree of immunosuppression increased with the degree of
unsaturation and fish oil was much more unsaturated than sunflower oil. Martin
asked the doctor why they were not talking about PUFs causing cancer. The doctor
replied that if he did that he would be run out of Oxford.
Carcinogens – background radiation,
ultraviolet radiation from the sun, particles in the air we breathe and the food
we eat – continually attack us all. Normally, the immune system deals with any
small focus of cancer cells so formed and that is the end of it. But linoleic
acid suppresses the immune system. With a high intake of margarine, therefore, a
tumour may grow too rapidly for the weakened immune system to cope thus
increasing our risk of a cancer.
Polyunsaturated fats cause cancer
Since 1974, the increase of polyunsaturated fats
has been blamed for the alarming increase in malignant melanoma (skin cancer) in
We are all told that the sun causes it. Are Australians going out in the sun any
more now than they were fifty years ago? They are certainly eating more
polyunsaturated oils: in Australia in 1995 I saw that even the cream on milk was
removed and replaced with vegetable oil. Victims of the disease have been found
to have polyunsaturated oils in their skin cells. Polyunsaturated oils are
oxidised readily by ultra-violet radiation from the sun and form harmful 'free
radicals'. These are known to damage the cell's DNA and this can lead to the
deregulation we call cancer. Saturated fats are stable. They do not oxidise and
form free radicals.
Malignant melanoma is also said to be increasing
in this country. Does the sun cause this? In Britain the number of sufferers is
so small as to be relatively insignificant. Even so, it is not likely that the
sun is to blame since all the significant increase is in the
over-seventy-five-year-olds. People in this age group tend to get very little
That the sun is not to blame is confirmed by
- Melanoma occurs ten times as often in Orkney
and Shetland than it does on Mediterranean islands.
- It also occurs more frequently on areas that
are not exposed to the sun.
- In Scotland, for example, there are five
times as many melanomas on the feet as on the hands;
- and in Japan, forty per cent of pedal
melanomas are on the soles of the feet . (13)
Polyunsaturated fats promote
Many laboratories have shown that diets high in
polyunsaturated fatty acids promote tumours. Cancer promotion is not the same as
cancer causing. The subject is complex; suffice to say here that promoters are
substances that help to speed up reproduction of existing cancer cells.
It has been known since the early 1970s that it
is linoleic acid that is the major culprit. As Professor Raymond Kearney of
Sydney University put it in 1987: 'Many laboratories have shown that a greater
proportion of polyunsaturated fats are superior to diets rich in saturated fats
in promoting the yield of experimental mammary tumours. In such studies, omega-6
linoleic acid appeared to be the crucial fatty acid . . .' and 'Vegetable oils (eg
Corn oil and sunflower oil) which are rich in linoleic acid are potent promoters
of tumour growth.' (14)
Polyunsaturated fats and breast
A study of 61,471 women aged forty to
seventy-six, conducted in Sweden, looked into the relation of different fats and
breast cancer. The results were published in January 1998. This study found an
inverse association with monounsaturated fat and a positive association with
polyunsaturated fat. In other words, monounsaturated fats protected against
breast cancer and polyunsaturated fats increased the risk. Saturated fats were
Flora margarine, the brand leader, is
thirty-nine percent linoleic acid; Vitalite and other 'own brand'
polyunsaturated margarines are similar. Of cooking oils, sunflower oil is fifty
percent and safflower oil seventy-two percent linoleic acid. Butter, on the
other hand, has only a mere two percent and lard is just nine percent linoleic
acid. Linoleic acid is one of the essential fatty acids. We must eat some to
live, but we do not need much. The amount in animal fats is quite sufficient.
Because of the heart disease risk from
trans-fats in margarines, in 1994 the manufacturers of Flora changed
its formula to cut out the trans fats and other manufacturers have since
followed. But that still leaves the linoleic acid.
The anti-cancer fat
Linoleic acid is one of the essential fatty
acids that our bodies need but cannot synthesise. We must eat some to survive.
Fortunately there is one form of linoleic acid that is beneficial. Conjugated
linoleic acid (CLA) differs from the normal form of linoleic acid only in the
position of two of the bonds that join its atoms. But this small difference has
been shown to give it powerful anti-cancer properties. Scientists at the
Department of Surgical Oncology, Roswell Park Cancer Institute, New York (16)
and the Department of Biochemistry and Molecular Biology, New Jersey Medical
showed that even at concentrations of less than one percent, CLA in the diet is
protective against several cancers including breast cancer, colorectal cancer
and malignant melanoma.
Conjugated linoleic acid has one other
difference from the usual form – it is not found in vegetables but in the fat
of ruminant animals. The best sources are dairy products and the fat on red
meat, principally beef. (18)
It has been suggested that the consumption of
red meat increases the risk of colon cancer, yet in Britain there is no evidence
to support this. (19)
It is interesting that all the evidence implicating red meat in cancer comes
from the USA – where they cut the fat off.
Saturated fats and animal fats are usually
blamed for all manner of diseases in Western society. But look at the facts:
- In the 19th-century, when animal fats were
all that was available, cancers were rare (as was heart disease).
- Polyunsaturated fats and oils are used to
suppress the immune system, such immunosuppression is known to cause cancers
to start and promote cancer.
- In this last century there has been a change
in favour of polyunsaturated fats and oils – and cancer rates have soared.
Unfortunately, as polyunsaturated fatty acids
are also essential to the body; we must have some. So a proper balance must be
struck. Whether the dramatic increase in the numbers of cancers in the last
century was as a result of a similarly dramatic rise in our intake of
polyunsaturated vegetable oils is not known – but the evidence strongly
favours such a conclusion.
Under the circumstances, it seems prudent to get
what linoleic acid we need from animal sources. Or to restrict polyunsaturated
oil consumption so that linoleic acid is no more than three percent of the total
1. Gofman, J W, et al. The
role of lipids and lipoproteins in atherosclerosis. Science 1950; 111:
2. Keys A. Atherosclerosis: a
problem in newer public health. J Mt Sinai Hosp 1953; 20: 118-139.
3. Mann G V. Diet-heart: End
of an Era. New Eng J Med . 1977; 297: 644.
4. Carroll K K. Dietary fats
and cancer. Am J Clin Nutr 1991; 53: 1064S.
5. France T, Brown P.
Test-tube cancers raise doubts over fats. New Scientist , 7 December
1991, p 12.
6. Newsholme E A. Mechanism
for starvation suppression and refeeding activity of infection. Lancet 1977;
7. Miller JD, et al. Br
Med J 1973; i: 765.
8. Uldall PR, et al .
Lancet 1974; ii: 514.
9. Pearce M L, Dayton S.
Incidence of cancer in men on a diet high in polyunsaturated fat. Lancet 1971;
10. American Heart
Association Monograph, No 25. 1969.
11. Nauts HC. Cancer
Research Institute Monograph No 18. 1984, p 91.
12. Mackie BS. Med J
Austr 1974; 1: 810.
13. Karnauchow PN. Melanoma
and sun exposure. Lancet 1995; 346: 915.
14. Kearney R. Promotion and
prevention of tumour growth – effects of endotoxin, inflammation and dietary
lipids. Int Clin Nutr Rev 1987; 7: 157.
15. Wolk A, et al. A
Prospective Study of Association of Monounsaturated Fat and Other Types of Fat
With Risk of Breast Cancer. Arch Intern Med . 1998; 158: 41-45
16. Ip C, Scimeca J A,
Thompson H J. Conjugated linoleic acid. A powerful anticarcinogen from animal
fat sources. Cancer 1994; 74(3 Suppl): 1050-4.
17. Shultz T D, Chew B P,
Seaman W R, Luedecke L O. Inhibitory effect of conjugated dienoic derivatives of
linoleic acid and beta-carotene on the in vitro growth of human cancer cells. Cancer
Letters 1992; 63: 125-133.
18. Lin H, Boylston TD,
Chang MJ, Luedecke LO, Schultz TD. Survey of the conjugated linoleic acid
contents of dairy products. J Dairy Sci . 1995; 78: 2358-65.
19. Cox BD, Whichelow MJ.
Frequent consumption of red meat is not a risk factor for cancer. Br Med J 1997;
Copyright © 2005
HealthSmart Nutrition. All rights reserved.
Revised: March 29, 2006