Polyunsaturated Fats Suppress The Immune System

by Barry Groves

Polyunsaturated fats (PUFs) are greatly immunosuppressive. The first person to suggest that polyunsaturated fats suppress the immune system was Dr E A Newsholme of Oxford University, England.[i] 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 existinginfection 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,[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.

This was in line with heart trials using diets that were high in PUFs which also reported an excess of cancer deaths from as early as 1971.[iv]

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 fed 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 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.

The late American cancer researcher, Wayne Martin, liked to tell a story which suggests just how cancer-causing are PUFs. In 1930 in the USA, he told me, 80% 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 beneficial in terms of heart disease protection. After this lung cancer deaths increased dramatically. By 1980 although the number of American men who smoked had dropped to only 30%, three times as much PUF was being eaten — and there were 60 times as manylung cancer deaths.[vi]

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.

With a high intake of margarine and cooking oils, therefore, a tumour may grow too rapidly for the weakened immune system to cope thus increasing our risk of a cancer.

And the same, of course, goes for any infectious disease.


[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.

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4 Responses

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  1. Judy Isaac says

    I realize, therefore, that all oils should be used sparingly by the healthy individual. What oils would you recommend for limited use in cooking and salad dressings? Olive oil? Is there another one that could be used with less pungent taste than olive oil?

    Thanks you

  2. Team FPS says

    All oils are not unhealthy. The saturated fats are protective. For cooking use butter, refined coconut oil, and ghee. For a salad dressing using vinegars, refined coconut oil, or olive oil (in small amounts). Make sure your olive oil is really olive oil by placing it into the refrigerator; it should start to get cloudy. If it stays very liquid, PUFA has been added and the oil should be discarded.

  3. Poul Skov says

    I understand the sunflower/vegetable oil argument, but not the fish oil statement. Does this mean that a diet high in fish oil, e.g. fatty fish is un-healthy? Are all un-saturated fats immune suppressing or are some of them ok or better than others? We always hear that olive and grape seed oil are healthy.

  4. Team FPS says

    Yes, a diet in high polyunsaturates relative to saturated fats is harmful for warm-blooded humans. The mainstream nutrition information is based in fairy tales and commercial and financial interests. Continue to peruse this blog to gain context and a more clear understanding of the toxicity of the polyunsaturates.

    Fish Oil Toxicity

    Errors in Nutrition: Essential Fatty Acids

    Dietary Fats, Temperature, and Your Body

    The Great Fish Oil Experiment

    PUFA, Fish Oil, and Alzheimers