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Dark side of Polyunsaturated fatty acids (PUFAs)

Polyunsaturated Fats Suppress The Immune System

The first person to suggest that polyunsaturated fats[PUFs] suppress the immune system
was Dr E A Newsholme of Oxford University, England. 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.
He was making the point that the immunosuppressive effects of PUFs in sunflower seeds are useful in treating autoimmune diseases such as multiple sclerosis,[ii] 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.[iii] (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 and the treatment was stopped.
In 1989 there was a report of a 10-year trial at a Veterans’ Administration Hospital in Los Angeles. In this trial half the patients were fed a diet which had twice as much PUFs as saturated fats. In the half of patients on the high PUF diet there was a 15% increase in cancer deaths compared to the saturated fat group.[v] The authors of the report said that the PUFs had been the cause of the increase in cancer deaths. The 6 October 1973 issue of the British Medical Journal asked if PUFs were carcinogenic and came to the conclusion that they were.
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 Oxford 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.


[i_]. Newsholme E A. Mechanism for starvation suppression and refeeding activity of infection. Lancet 1977; i: 654.

[ii]. Miller JHD, et al. Double blind trial of linoleate supplementation in the diet in multiple sclerosis. BMJ 1973; i: 765-8.

[iii]. Uldall PR, et al. Unsaturated fatty acids and renal transplantation. Lancet 1974; ii: 514.

[iv]. Pearce M L, Dayton S. Incidence of cancer in men on a diet high in polyunsaturated fat. Lancet 1971; i: 464.

[v]. American Heart Association Monograph, No 25. 1969.

[vi]. Nauts HC. Cancer Research Institute Monograph No 18. 1984, p 91.

Dietary fish oil and flaxseed oil suppress inflammation and immunity in cats
Fish and flaxseed oils lowered B, total T and T(h) subset populations, and leukocyte proliferative response to PWM

Monounsaturated fats and immune function

In a study comparing the effects of diets A-I (Table 1) on NK cell activity, there was a significant negative linear relationship between the oleic acid content of the diet and NK cell activity, suggesting that dietary oleic acid causes diminished NK cell activity (19; Figure 8).

Omega-6 polyunsaturated fatty acids: Is a broad cholesterol-lowering health claim appropriate?
...when saturated fats were replaced with polyunsaturated fatty acids, there was a statistically significant reduction in total and low-density lipoprotein (LDL) cholesterol...
Ramsden and colleagues recently completed a detailed reanalysis of recovered data from the Sydney Diet Heart Study, in which the intervention group replaced saturated fat with sources of safflower oil or safflower oil margarine (rich in omega-6 linoleic acid but low in omega-3 α-linoleic acid).5 They found that the intervention group had serum cholesterol levels that were significantly decreased (by about 8%–13%) relative to baseline and the control group, which is consistent with the health claim. However, the intervention group had significantly higher rates of death than the control group (all cause 17.6% v. 11.8% [hazard ratio (HR) 1.62, 95% CI 1.00–2.64]; cardiovascular disease 17.2% v. 11.0% [HR 1.70, 95% CI 1.03–2.80]; and coronary artery disease 16.3% v. 10.1% [HR 1.74, 95% CI 1.04–2.92]).
Key points:
The replacement of dietary saturated fats with some, but not all polyunsaturated fatty acids reduces serum cholesterol levels and the risk of heart disease.
New analyses suggest that replacing saturated animal fats with linoleic acid, an omega-6 polyunsaturated fatty acid, lowers serum cholesterol levels but increases the risk of death from coronary artery disease.
Health Canada’s Food Directorate should reconsider the health claim that omega-6 polyunsaturated fatty acids reduce the risk of heart disease by lowering blood cholesterol levels.

Ourania has reacted to this post.

Hi @rockarolla,

Thanks for posting that information.

The PUFAs do affect the vA serum level and the storage rate of vA in the liver.







puddleduck, Ourania and rockarolla have reacted to this post.

VA is basically a PUFA, compare the chemical structure of any VA molecule with an unsaturated fatty acid, all VA molecules have a highly unsaturated hydrophobic tail to them which makes them insoluble in water and highly prone to oxidation, this same affinity for fat and aversion to water is also the reason why VA builds up in every tissue including the brain because fat soluble molecules and fats themselves cannot be processed by the kidneys so they need to be sequestered into fat tissue before excretion in bile or until metabolic processes change the molecules to be able to be able to be processed by the kidneys so the net result, depending on high PUFA or/and high VA intake, is a bunch of unstable molecules lining the membranes of every cell in our bodies for years. As far as I can tell this is the most salient reason for the damage VA and PUFA does, however it may very well be because of other processes

There is also a very simple test to determine the level of instability of a fats, or a mixture of fats and that is the measurement of the iodine value https://en.wikipedia.org/wiki/Iodine_value, sadly studies on the iodine value of human plasma & tissue are severely lacking, though it is used in the pork industry to determine fat quality where the higher the level of unsaturation, the worse the quality. An interesting test would be to measure the iodine value of a solution of retinol or beta-carotene and compare the value to a PUFA, or to separate the fat soluble molecules from blood and take the iodine value of that solution & compare it the iodine values of known fatty acids. I'd like to perform these tests in the future, but having somebody who's versed in chemistry do them would be much better




Orion, lil chick and 3 other users have reacted to this post.
Orionlil chickOuraniarockarollaДаниил

I suppose that is one thing to my benefit is that I've never eaten many PUFAS, however, it hasn't stopped me from being where I am, LOL.  But then again, maybe I'd be dead otherwise.  Of course, I've eaten 5000 pounds of butter at least, LOL.