Re: Are Polyunsaturated Fats really safe?

[Guest guest]

: I tried the link you gave and it was no good. So where exactly

did this article come from? Also no date on this. Although the references

at the end of the article are all very dated (some as far back as 1950).

Please post a good link or where this came from. There are all sorts of

places on the web saying any old thing and unless the source is reputable,

and credible, please do not use here.

on 2/20/2005 8:58 AM, rwalkerad1970 at rwalkerad1970@... wrote:

>

> I have comes across a number of studies against polyunsaturated

> fats, in relation to immune system and cancer. A good selection

> are listed in the article below (whole article can be got here:

> http://www.second-opinions.co.uk/fats_and_cancer.html. And I don't

> want to start up the saturated fat debate again.

>

[Guest guest]

> : I tried the link you gave and it was no good.

Fancesca, try http://www.second-opinions.co.uk/fats_and_cancer.html ;

added a point at the end of the link, and that was the

problem.

Willie.

[Guest guest]

Hi :

Thanks for the studies questioning polys. Just for clarification:

1. I do not advocate eating any more than one has to of any fat

(except, perhaps, EPA and DHA). My current diet is slightly below

20% of calories from fat, and for many years it was around 10%. It

has risen since I have increased my intake of fish and nuts. And the

benefit from nuts is probably not from their oil content, as Willie

suggested here a week or so ago.

2. We DO know (I think!) that LA is an essential nutrient.

3. Those studies that used corn oil as their source of LA **may**

have been confounded by corn products' occasional " unavoidable "

aflatoxin contamination.

4. In my view people on CR probably need to pay more attention to

cancer than to heart disease. So, if that is indeed correct, it is

especially helpful for us here to be acquainted with any possible

carcinogenic effects of foods generally eaten because of their

apparent benefits for CVD.

So thanks for those study references, but I am not yet persuaded. If

the Nurses' Health Study were to come out with something on this -

i.e. clear empirical evidence from a large north american population

over a long time span - I would certainly sit up and make sure to

consume no more than the 'RDA'.

Rodney.

>

> I have comes across a number of studies against polyunsaturated

> fats, in relation to immune system and cancer. A good selection

> are listed in the article below (whole article can be got here:

> http://www.second-opinions.co.uk/fats_and_cancer.html. And I don't

> want to start up the saturated fat debate again.

>

> But I would like to know how we can gamble reducing LDL via

> increasing poly fats to lower CHD risk when there is the potential

> life threatening condition of cancer as the alternative.

>

> Personally having now looked at many studies using the statistical

P

> value I think that all assumptions made using that statistical

> equation are not worth the paper they are written upon, it is, to

> me, all really shoddy science open to massive coincidence,

> manipulation and failing to factor in various dietary disease risks

> that have yet to be discovered.

>

> But Rodney and Tony have both mentioned polyunsaturated fats in a

> good light recently so I think this balances the perspective a

> little. Personally I don't have a clue was going on, so will just

> stick to 5% calories from poly fats for now.

>

> ...

>

>

> 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.

>

> 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 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 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, called Newsholme's Oxford University office but by

> then Newsholme had retired. 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. 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 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. 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, 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. BD, Whichelow MJ. Frequent consumption of red meat is not a

> risk factor for cancer. Br Med J 1997; 315: 1018.

[Guest guest]

Hi Rodney and All,

How is your posture after reading the below.

Lower cholesterol and die over twice as often? It is not my idea of

where to go.

Cheers, Al.

Prostaglandins Leukot Essent Fatty Acids. 1997 Oct;57(4-5):423-7.

Dietary management of cardiovascular diseases.

Renaud SC.

Since cholesterol was discovered in atherosclerotic plaques and was

able, when given in diet, to induce the same type of lesions in

animals, the aim of previous dietary changes was to reduce serum

cholesterol as much as possible. For this purpose, the intake of

saturated fats was decreased and replaced by linoleic acid, the main

fatty acid lowering cholesterol. Nevertheless, this type of diet in

primary or secondary prevention did not succeed in reducing

satisfactorily cardiovascular and total mortality unless the intake

of fish (DART and Hjermann trials) i.e. of n-3 fatty acids, was

increased. On the other hand, the diet with the greatest life

expectancy in the western world is that of Crete, largely vegetarian

with a high intake of alpha-linolenic acid. Such a diet, compared to

the usual prudent diet in 600 patients after a first myocardial

infarction, reduced within a few months all cause mortality and

cardiovascular events by more than 70%. Thus a highly palatable diet

adapted from Crete seems to be much more efficient to prevent

recurrences and death after a first myocardial infarction than the

hypocholesterolemic diet presently advised.

PMID: 9430390 [PubMed - indexed for MEDLINE]

--- In , " Rodney " <perspect1111@y...>

wrote:

>

> Hi :

>

> Thanks for the studies questioning polys. Just for clarification:

>

> 1. I do not advocate eating any more than one has to of any fat

> (except, perhaps, EPA and DHA). My current diet is slightly below

> 20% of calories from fat, and for many years it was around 10%. It

> has risen since I have increased my intake of fish and nuts. And

the

> benefit from nuts is probably not from their oil content, as Willie

> suggested here a week or so ago.

>

> 2. We DO know (I think!) that LA is an essential nutrient.

>

> 3. Those studies that used corn oil as their source of LA **may**

> have been confounded by corn products' occasional " unavoidable "

> aflatoxin contamination.

>

> 4. In my view people on CR probably need to pay more attention to

> cancer than to heart disease. So, if that is indeed correct, it is

> especially helpful for us here to be acquainted with any possible

> carcinogenic effects of foods generally eaten because of their

> apparent benefits for CVD.

>

> So thanks for those study references, but I am not yet persuaded.

If

> the Nurses' Health Study were to come out with something on this -

> i.e. clear empirical evidence from a large north american

population

> over a long time span - I would certainly sit up and make sure to

> consume no more than the 'RDA'.

[Guest guest]

Hi folks:

" But that doesn't in anyway mean anything in relation to a truly

healthier diet as I have espoused here. "

Indeed, a study I posted here within the past week, done by greeks in

Crete, indicates that the cretan diet, with its huge consumption of

olive oil is far from ideal ................. because it showed

that the people in Crete who suffered the most heart disease were

those who consumed the most monounsaturated oil (olive)!

For a start, drastically cut consumption of olive oil, presumably.

Plenty of room for improvement, apparently.

Rodney.

--- In , " Jeff Novick " <jnovick@p...>

wrote:

> >>Thus a highly palatable diet adapted from Crete seems to be much

more efficient to prevent

> recurrences and death after a first myocardial infarction than the

hypocholesterolemic diet presently advised.

>

> Agreed 100%.

>

> But that doesnt in anyway mean anything in relation to a truly

healthier diet as I have espoused here.

>

> Regards

> Jeff