Polyunsaturated Fats Cause Cancer – LA Veterans Trial

The Wadsworth VA Hospital in Los Angeles operated a home where male army veterans resided. The meals were provided by one of two dining halls.

Men in dining Hall A continued their usual diet. The “saturated animal fat and hydrogenated shortening replaced with vegetable oils in the experimental diet” for the diets provided in dining Hall B. Low fat diets were not considered because such a diet required “gastronomic sacrifice”. The total fat content of the 2 diets were the same, providing 40% of the total energy. (Diets of 40% fat cannot be considered a healthy diet.)[1]

Both groups were told that their diet had changed. The compliance rates 56% for the control diet and 49% for experimental diet.

846 men, most of them in their 60s or 70s, were randomly assigned to one or the other dining room and followed for up to 8 years. Average age at the start of the study was 65.5. The study was carried out in the late 1950s by Seymour Dayton and Morton Pearce from the University of California.

The blood cholesterol of the experimental group fell 12.7%. The number of events (definite heart attack, fatal or nonfatal; stroke; or peripheral atherosclerosis requiring amputation) was reduced by 31% in the experimental group (48 versus 70).[2]


This is how David Gillespie commented on the trial in Toxic Oil.

A much larger trial, completed in 1971, was conducted with a population of 846 Californian military veterans in domiciled care randomly assigned to two different diets. In the Veterans Trial, one kitchen replaced all animal-fat products with corn oil for the eight-year duration of the study. The other kitchen kept on serving a normal high-animal-fat diet. As expected, the corn-oil group had a lower average blood-cholesterol level by the end of the trial, although the ‘improvement’ (13 per cent) wasn’t as great as in the London Hospital Study. Heart-disease-related events were slightly fewer than expected in both groups, but not significantly different from each other. But what really concerned the researchers was the dramatic difference in cancer deaths between the two groups. The incidence of fatal cancers in the corn-oil group was nearly double that of the normal-diet group.[3]

Gillespie transforms the significant 31% reduction in cardiovascular events to be “not significantly different from each other”. Similarly, he transforms the non-significant increase in carcinoma deaths into a finding that “really concerned the researchers”.

Compare the above with how Seymour Dayton reported his findings in The Lancet.

Many of the cancer deaths in the experimental group were among those who did not adhere closely to the diet. This reduces the possibility that the feeding of polyunsaturated oils was responsible for the excess carcinoma mortality observed in the experimental group.During the late part of the trial there was a crossover of the curves for total death-rates due to an excess nonatherosclerotic mortality among experimental subjects. In this phase of the trial, numbers were relatively small and the excess nonatherosclerotic mortality after the sixth anniversary accounted for 9 cases. The differences in nonatherosclerotic deaths in this period was entirely due to trauma (0 controls, 4 experimental) and to carcinoma (2 controls, 7 experimental).[4]

The author does point out that these differences occurred only in the older group of veterans – not in the younger group. There is also a difference in smoking patterns between the experimental and control groups – although this is probably not significant. This paper states that the difference in cancer rates between the two groups is “non-significant”. This is far from a finding that “really concerned the researchers”.

MJ Karvonen from Finland reported on diets high in polyunsaturated fats and incidence of cancer.

In the Los Angeles veterans study, a statistically non-significant excess of cancer incidence and of cancer mortality was reported among those on the experimental diet (Dayton et al. 1969; Pearce & Dayton, 1971). This, however, has not been the rule in other similar studies. And when the results of five studies (Oslo, London, Helsinki, Faribault and Los Angeles) were combined, the total mortality of those on the diet was only 85% of that of their controls. There was no significant difference in cancer incidence or mortality in the combined material (Ederer, Leren, Turpeinen & Frantz, 1971).[5]
The premise that diets high in polyunsaturated fats contribute to cancer can not be substantiated.

Footnotes

  1. Dayton, S. et al. (1969) A controlled clinical trial of a diet high in unsaturated fat in preventing complications of atherosclerosis. Circulation. 40 (1S2), II-1.
  2. Steinberg, D. (2007) The Cholesterol Wars: The Skeptics vs. the Preponderance of Evidence. San Diego, CA: Academic Press.
  3. Gillespie, D. (2013) Toxic Oil: Why Vegetable Oil Will Kill You & How to Save Yourself. Viking.
  4. Pearce, M. L. & Dayton, S. (1971) Incidence of Cancer in Men on a Diet High in Polyunsaturated Fat. The Lancet. 297 (7697), 464–467.
  5. Karvonen, M. J. (1972) Modification of the diet in primary prevention trials. The Proceedings of the Nutrition Society. 31 (1), 355–362.

Leave a Reply

Your email address will not be published. Required fields are marked *