Polyunsaturated oils increase cancer risk

[Guest guest]

http://www.second-opinions.co.uk/fats_and_cancer.html

 

Introduction

 

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

heart disease.

 

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.

 

Before 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 promoted.

 

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:

 

Butter:

milk fat (cream),

a little salt,

 

Margarine:

Edible oils,

edible fats,

salt or potassium chloride,

ascorbyl palmitate,

butylated hydroxyanisole,

phospholipids,

tert-butylhydroquinone,

mono- and di-glycerides of fat-forming fatty acids,

disodium guanylate,

diacetyltartaric and fatty acid esters of glycerol,

Propyl, octyl or dodecyl gallate (or mixtures thereof),

tocopherols,

propylene glycol mono- and di-esters,

sucrose esters of fatty acids,

curcumin,

annatto extracts,

tartaric acid,

3,5,trimethylhexanal,

ß-apo-carotenoic acid methyl or ethyl ester,

skim milk powder,

xanthophylls,

canthaxanthin,

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 unstable.

 

[chart]

 

Fatty acids in human fat

 

Polyunsaturated fats suppress the immune system

 

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 expected.

 

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 deaths.

(11)

 

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

Australia. (12) 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 sun.

 

That the sun is not to blame is confirmed by other findings:

 

* 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 cancer

 

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 cancer

 

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 neutral. (15)

 

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 School, (17) 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.

 

Conclusions

 

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 fat intake.

 

References

 

1. Gofman, J W, et al. The role of lipids and lipoproteins in

atherosclerosis. Science 1950; 111: 166-181, 186

 

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; i: 654.

 

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; i: 464.

 

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; 315: 1018.

[Guest guest]

Here is a little experiment you can do at home. Take a pat of

butter, put it on a paper plate, and staple the plate to your windowledge,

outside the window. Observe the butter over a week. Bugs will eat it.

Birds will eat it. What the bugs and birds don't eat will go all moldy.

 

Now, repeat the experiment using a pat of margarine. The birds

won't eat it. The bugs won't eat it. It won't go moldy.

 

Now, if the birds, bugs, and microflora don't want the margarine,

why should us humans?

 

Alobar

 

-

" Naomi Giuliano " <n.giuliano

 

Sunday, June 19, 2005 6:23 AM

Polyunsaturated oils increase cancer

risk

 

 

http://www.second-opinions.co.uk/fats_and_cancer.html

[Guest guest]

On 6/19/05, Pipetman9 <Pipetman9 wrote:

> yes, for more than half a century it is known that PUFA like flax oil or fish

> oil or sunflower oil produce toxic lipidperoxides that are a main factor of

> cancer and most other disease of civilisation. Those who want to sell PUFA

> call them essential fatty acids or Vitamin F.

>

>

I'm trying to reduce my consumption of PUFA as much as possible. I've

eliminated all but small amounts of what's in fish and cod liver oil,

nuts, and virgin olive oil (which I sometimes use for salad dressings,

and I include a little flax oil with it).

 

Naomi