Updated: Sep 8, 2021
I want to start today's article with a simple question that I want everyone to think about. Wouldn't it be logical that if there was some drug or diet that could reverse coronary artery disease (CAD), every mainstream board certified cardiologist, cardiothoracic surgeon, The Dietary Guidelines for Americans, The American Heart Association, and The American College of Cardiology would recommend whatever is necessary to "clean the pipes" since that is what is the #1 killer of men and women in the US? The answer is yes! Of course we would, and I would be leading the pack.The Ornish website proclaims that their program is the first program “scientifically proven to undo (reverse) heart disease.” That’s a huge claim, but the simple truth is that there is nothing "scientifically" proven to undo heart disease.
You may be asking yourself why would Dean Ornish pushing his program if it doesn't work to the clean the coronary arteries and has never be proven in a rigorous scientific study. However, supporters of vegetarian/ultra low fat diets like to claim that there is solid scientific evidence of the cardiovascular benefits of their chosen diets.
Who is Dean Ornish?
Most people do not know the background of Dean Ornish. Dean Ornish has an MD degree from Baylor University and trained in internal medicine but has no formal cardiology or nutrition training (although many internet sites including Wikipedia describe him as a cardiologist.) Ornish, according to the Encyclopedia of World Biographies became depressed and suicidal in college and underwent psychotherapy “but it was only when he met the man who had helped his older sister overcome her debilitating migraine headaches that his own outlook vastly improved. Under the watch of his new mentor, Swami Satchidananda, Ornish began yoga, meditation, and a vegetarian diet, and even spent time at the Swami’s Virginia center.”
Can the Ornish Diet Reverse Heart Disease?
After his medical training Ornish founded the Preventive Medicine Research Institute and has has widely promoted his Ornish Lifestyle Program. the website of which claims:
Dr. Ornish’s Program for Reversing Heart Disease® is the first program scientifically proven to “undo” (reverse) heart disease by making comprehensive lifestyle changes.
The Ornish claims are based on a study he performed between 1986 and 1992 which originally had 28 patients with coronary artery disease in an experimental arm and 20 in a control group. There are so many limitations to this study that the mind boggles that it was published in a reputable journal.
193 patients with significant coronary lesions from coronary angiography were “identified” but only 93 “remained eligible.” These were “randomly” assigned to the experimental or control groups. Somehow , this randomization process assigned 53 to the experimental group and 40 to the usual-care control group. If this were truly a 1:1 randomization the numbers would be equal and the baseline characteristics equal. Only 23 of the 53 assigned to the experimental group agreed to participate and only 20 of the control group. The control group was older, less likely to be employed and less educated. “The primary reason for refusal in the experimental group was not wanting to undergo intensive lifestyle changes and/or not wanting a second coronary angiogram; control patients refused primarily because they did not want to undergo a second angiogram.”
In other words, all of the slackers were weeded out of the experimental group and all of the patients who were intensely motivated to change their lifestyle were weeded out of the control group. Gee, I wonder which group will do better?
What was the measurement?
Progression or regression of coronary artery lesions was assessed in both groups by quantitative coronary angiography (QCA) at baseline and after about a year. QCA as a test for assessing coronary artery disease has a number of limitations and as a result is no longer utilized for this purpose in clinical trials. When investigators want to know if an intervention is improving CAD they use techniques such as intravascular ultraound or coronary CT angiography which allow measurement of total atherosclerotic plaque burden.
Ornish has widely promoted this heavily flawed study as showing “reversal of heart disease” because at one year the average percent coronary artery stenosis by angiogram had dropped from 40% to 37.8% in the intensive lifestyle group and increased from 42.7% to 46.1% in the control patients.
The minimal diameter (meaning the tightest stenosis) changed from 1.64 mm at baseline in the experimental to 1.65 at one year. At 5 years the minimal diameter had increased another whopping .001 mm to 1.651. In other words even if we overlook the huge methodologic flaws in the study the so-called “reversal” was minuscule. Utlimately, dropping coronary artery blockages by <5 % doesn’t really matter unless that is also helping to prevent heart attacks or death or strokes or some outcome that really matters.There were no significant differences between the groups at 5 years in hard events such as heart attack or death. In fact 2 of the experimental group died versus 1 of the control group by 5 years.There were less stents and bypasses performed in the Ornish group but the decision to proceed to stent or bypass is notoriously capricious when performed outside the setting of acute MI. The patients in the experimental group under the guidance of Ornish and their Ornish counselors would be strongly motivated to do everything possible to avoid intervention.
Although often cited as justification of ultralow fat diet, the Ornish Lifestyle trial doesn’t test diet alone. It is a trial of multiple different interventions with frequent counseling and meetings to reinforce and guide patients. The interventions included things that we know are really important for long term health-regular exercise, smoking cessation, and weight management. These factors alone could account for any differences in the outcome but they are easily adopted without becoming a vegetarian. The patients who agreed to the experimental arm were a clearly highly motivated bunch who agreed to this really strict regimen. Even in this population there was a 25% drop out rate.
Since investigators clearly knew who the “experimental patients” were and they were clearly interested in good outcomes in these patients there is a high possibility of bias in reporting outcomes and referring for interventions. Despite all the limitations the study does raise an interesting hypothesis. Should we all be eating vegan diets? If Ornish really wanted to scientifically prove his approach he should have repeated it with much better methodology and much larger numbers.
Finally, this tiny study has never been reproduced at any other center.
Because of the small numbers, lack of true blinding, lack of hard outcomes and use of multiple modalities for lifestyle intervention, this study cannot be used to support the Ornish approach.
It most certainly doesn’t show that the Ornish Lifestyle Program “reverses heart disease.” Consequently, you will not find any evidence-based source of nutritional information or guideline (unless it has a vegan/vegetarian philosophy or is being funded by the Ornish/Pritikin lifestyle money-making machines) recommending these diets.