Does the Ornish Diet Reverse Heart Disease?

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I first heard about the Ornish Diet during medical school. I was told that this diet was the only diet proven to cause regression of artery plaques and that everyone should be eating this way.

I have had a couple of patients who went on the Ornish Diet because they had heard that Dr Ornish’s diet had completely cleared the arteries of plaque.

Cardiovascular disease is the leading cause of death in the United States and my primary focus is optimal health and prevention of disease. I will implement any therapy or intervention that helps us achieve that goal.

Since I’d heard so much about the benefits of the Ornish Diet I decided to review the data myself. Here is a summary of his study.

Dean Ornish, MD demonstrated a minor reduction in artery stenosis. That means he states that he was able to increase the size of the arteries using his diet and lifestyle changes. Let’s take a look at his study.

The name of his study was “Intensive Lifestyle Changes for Reversal of Coronary Heart Disease” and was published in JAMA, December, 1998.

Originally 93 patients met criteria to be included in the study and these 93 were then randomized into the control group and the experimental group. Each of these patients had coronary atherosclerosis documented by quantitative coronary arteriography. However, after randomization, only 28 of the experimental group patients agreed to participate and only 20 of the control group agreed to participate.

These patients were originally to receive a 2nd angiogram at 1 year but the study was later extended so these patients were to have a 3rd angiogram at year 5. 20 experimental patients and 15 control patients continued the study and had an angiogram at 5 years.

The experimental (intervention) group:

These patients received moderate aerobic exercise, stress management training, smoking cessation, group psychosocial support, and a 10%-fat vegetarian diet. They were instructed to avoid simple sugars and to emphasize the intake of complex carbs and other whole foods.

The control group:

These patients were told to follow the advice of their primary physician.

Coronary Artery Lesions:

Angiography was performed at baseline, 1 year, and 5 years. The Ornish Diet improved coronary artery stenosis whereas the traditional approach had an increase in stenosis.

  • Ornish – stenosis improved from 38.92% at baseline to 35.85% at 5 years. This is a 3.07% absolute improvement.
  • Traditional – stenosis worsened from 42.50% at baseline to 54.27% at 5 years. They got worse by 11.77%.

Interestingly, the Ornish group with the highest adherence had the best effect while those with the lowest adherence did halt progression of stenosis but did not have regression.

In the ‘traditional’ group they analyzed those who started lipid-lowering medications:

  • Lipid lowering meds – stenosis progressed from 45.7% to 51.7% (absolute difference of 6%)
  • No lipid lowering meds – stenosis progressed from 45.7% to 59.7% (absolute difference of 19%)

Risk Factor Changes:

  • Ornish –
    • weight – lost 23.9 lbs at 1 year but gained some back for a total loss of 12.8 lbs at 5 years
    • LDL – decreased from 143.8 mg/dL at baseline to 115.35 mg/dL at 5 years (28.45 mg/dL change) but the P value was 0.76 which makes this statistically insignificant.
    • ApoB – increased from 1.000 to 1.014
    • HDL – decreased from 40.05 mg/dL to 34.75 mg/dL (5.3 mg/dL change)
    • Triglycerides – increased from 227.8 mg/dL to 236.1 mg/dL (8.3 mg/dL change)
    • Blood pressure – decreased from 135/82 to 130/77
  • Traditional –
    • no significant change is weight at 1 or 5 years
    • LDL – decreased from 166.40 mg/dL at baseline to 133.8 mg/dL at 5 years (32.6 mg/dL change)
    • ApoB – decreased from 1.024 to 0.991
    • HDL – decreased from 52.36 mg/dL to 49.27 mg/dL (3.09 mg/dL change)
    • Triglycerides – decreased from 223.3 mg/dL to 211.5 mg/dL (11.8 mg/dL change)
    • Blood pressure – decreased from 137/80 to 123/74

Of note, the change in BMI was significantly correlated with the change in stenosis in the control group only. Those who gained weight were more likely to show progression of their atherosclerosis.


  • Ornish:
    • Frequency (x/wk) – decreased from 5.8 to 1.6
    • Duration (minutes) – decreased from 3.1 to 0.9
    • Severity (1-7 scale) – decreased from 1.5 to 0.9
  • Traditional:
    • Frequency (x/wk) – decreased from 1.4 to 0.9
    • Duration (minutes) – decreased from 3.2 to 1.0
    • Severity (1-7 scale) – decreased from 0.6 to 0.6

It should be noted here that 5 patients in the traditional group reported increased angina and 3 of these patients underwent coronary angioplasty between years 1 and 5. In my opinion, these results should have been excluded as you are now comparing a dietary intervention with a surgical intervention and confounds the results making them uninterpretable.

Also, the P Value for all 3 measurements was statistically insignificant at 5 years. This means that all of these reductions could have occurred by chance alone.

Cardiac Events:

The number of cardiac events during the 5 year follow up:

  • Ornish
    • Myocardial infarction – 2
    • Angioplasty – 8*
    • Coronary artery bypass graft – 2
    • Cardiac hospitalizations – 23*
    • Deaths – 2
    • Any event – 25*
  • Traditional
    • Myocardial infarction – 4
    • Angioplasty – 14*
    • Coronary artery bypass graft – 5
    • Cardiac hospitalizations – 44*
    • Deaths – 1
    • Any event – 45*

*Only these events were statistically significant between groups.

I find it interesting that twice as many people died in the treatment group. Of course, this means nothing in regards to the study itself.


There was a statistically significant difference in the primary outcome between the Ornish (experimental or treatment) group and the control group. While the Ornish intervention was beneficial when compared to the traditional medical approach we must use caution in interpreting these results. I wonder if this outcome has less to do with the benefits of the Ornish intervention or the detriment of the traditional medical approach.

One conclusion is that patients with cardiovascular atherosclerosis should be on the Ornish Diet & Intervention. However, another plausible conclusion is that no patients with atherosclerosis should be following the traditional medical approach and advice from their doctor.

This study is actually doing a head to head comparison of two different interventions. It would be interesting to see a study comparing the Ornish Diet to a group doing nothing different than the patient would normally do on their own.

There are multiple outcomes that are reported in the study: LDL, HDL, weight, blood pressure, artery stenosis, chest pain, etc. The Ornish Diet does appear to improve outcomes related to cardiovascular disease when compared to the traditional medical approach. However, a larger sample size would most likely provide more clarity.

There are several factors that confound the results of this study including limited study population and mid-study interventions such as angioplasty for worsening angina.

Clearly, we want as much improvement in the artery as possible and the Ornish Diet does seem to have benefit in this regard. However, we are more than simply arteries. Low fat diets have been shown to be detrimental for cognitive function as well as numerous other parameters. We should exercise extreme caution in recommending these low-fat diets when we are trying to optimize the overall health of our patients. While I don’t believe that a low-fat dietary approach is the best for optimal health, it does appear to be a better approach than simply following your typical doctor’s advice.