Coronary heart disease is a multifactorial disease that requires multifactorial intervention. This is the view of Dr. Dean Ornish and his group at the Preventive Medicine Research Institute, Sausalito, California, a view they share with many other doctors and researchers. Dr. Ornish and his group chose to intervene with a lowfat, low-cholesterol vegetarian diet, stopping smoking, stress-management training and moderate exercise. They selected 94 patients with a diagnosis of coronary artery disease according to a previous coronary angiogram. Fifty-three were randomly assigned to the experimental group and 43 to the control group, but when told about the design of the study only 28 and 20, respectively, agreed to participate.
A new angiogram was performed after one year, but one of the angiograms disappeared; in three patients the second angiogram could not be evaluated; one patient was not studied because of unpaid bills; one died during heavy exercise; and one dropped out because of alcohol misuse. Thus, only 22 patients in the experimental group and nineteen in the control group were available for analysis.
The result seemed promising. In the treatment group the total cholesterol fell by an average of 24 percent and LDL-cholesterol by 37 percent; mean body weight had decreased by ten kilograms; less severe chest pains were reported; and the coronary arteries had widened a little, whereas they had become a little more narrow in the control group. These improvements were strongly related to the degree of adherence to the intervention program in a “dose-response” manner, as the authors wrote in their report. The vascular improvements were still there after a prolongation of the study by five years, but now the difference was calculated using the less-demanding one-sided t-test. Unfortunately, there was no difference in frequency, duration or severity of angina between the groups, but this unexpected finding was “most likely” due to bypass operations performed in the control group. Nothing was mentioned about how many operations had been performed, however, and no comparison was made between those who had not had an operation. In addition, a further six individuals were unavailable for follow-up study.
And there were more flaws. Not only was it an unblinded study (although in the latest publication it was called blinded!), the low number of participants also resulted in a most uneven distribution of the risk factors. For instance, at the start the mean age was four years higher, mean total cholesterol 8 percent higher and mean LDL-cholesterol 10 percent higher in the control group; but mean body weight was almost 25 pounds higher in the treatment group. Such large differences between risk factors obviously complicate the evaluation of the treatment effect.
But let us assume that the improvement of the treated individuals was true and a result of the intervention—and this may well be possible—which of the intervention measures had a beneficial effect? Was it a weight reduction of more than 25 pounds? Was it a difference in smoking habits? (One in the experimental group smoked and stopped; nothing was mentioned about the number of smokers in the control group.) Was it the exercise? Was it the inner sense of peace and well-being produced by the stress-management education? Or was it a combination of these factors?
That the diet had any importance is unlikely because there is no evidence that vegetarians have a lower risk of coronary disease than other people. It is also unlikely that it was the change in LDL-cholesterol levels because at the end of the study there were no significant differences between these values in the two groups. The latter also contradicts the statement that the changes of coronary atherosclerosis and the diet were strongly correlated in a “dose-response” manner. To the pertinent question “Precisely how strong were the correlations?” asked by Elaine R. Monsen, editor of Journal of the American Dietetic Association, Dr. Ornish answered that “the study wasn’t really set up to do these kinds of analyses, so when we get beyond saying they’re correlated, we’re on shaky ground.”
It is laudable to try prevention without drugs, and we already know it may be health-promoting to avoid being overweight, to exercise a little and to avoid smoking and mental stress, but with such weak evidence, why bother millions of people with a diet that only rabbits may find tolerable? Perhaps the results would have been better if the patients’ inner sense of peace and well-being had been strengthened even more by allowing them to follow a more appealing and nutritious diet!
- Ornish D and others. Can lifestyle changes reverse coronary heart disease? The Lifestyle Heart Trial. The Lancet 336, 129-133, 1990.
- Ornish D. Reversing heart disease through diet, exercise and stress management: An interview with Dean Ornish. Journal of the American Dietetic Association 91, 162-165, 1991.
- Gould KL, Ornish D and others. Changes in myocardial perfusion abnormalities by positron emission tomography after long-term, intense risk factor modification. Journal of the American Medical Association 274, 894-901, 1995.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Spring 2001.