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Flaws of the Dr. Ornish' study

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Flaws of the Dr. Ornish' study

Posted by R. on June 21, 2002 at 03:53:07:

The following article exposes flaws, from a scientific point of view, of the famous Dr. Ornish study. It would be good if the low-fat diet promoters read this. This is a good example of clear scientific thinking. I wish more doctors had it. I got the article from Weston A. Price Foundation site (http://www.westonaprice.org/moderndiseases/hd.html). It is actually excerpted from The Cholesterol Myths by Uffe Ravnskov, MD, PhD. For more about him, go to http://www.ravnskov.nu/uffe.htm.
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Dr. Ornish and the Lifestyle Heart Trial
from The Cholesterol Myths by Uffe Ravnskov, MD, PhD

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.)



Re: Flaws of the Dr. Ornish' study

Posted by
thessa on June 21, 2002 at 07:57:28:

In Reply to: Flaws of the Dr. Ornish' study posted by R. on June 21, 2002 at 03:53:07:

personally i give only a certain amount of weight to studies (in either camp) in my overall research and formation of conclusions, but as long as we are on the study wagon...

"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. "
http://www.llu.edu/llu/nutrition/program/research4.htm
http://www.findarticles.com/cf_0/m0820/n229/18612455/print.jhtml
http://www.veggiedoc.com/medlit/medlit_heartdisease.htm
http://www.viva.org.uk/Viva!Guides/guide7b.htm

and a decent article discussing fat in the vegetarian diet
http://www.andrews.edu/NUFS/challenge%20of%20defining%20optimal%20fat%20intake.html



Re: Flaws of the Dr. Ornish' study (links enabled)

Posted by link enabler on June 21, 2002 at 09:33:29:

In Reply to: Re: Flaws of the Dr. Ornish' study posted by thessa on June 21, 2002 at 07:57:28:

link 1 (research)

link 2 (findatricle)

link 3 (veggiedoc)

link 4 (Viva)

A decent article discussing fat in the vegetarian diet
link 5 (the vegetarian diet)




thanks link enabler .... nmi

Posted by
thessa on June 21, 2002 at 10:45:59:

In Reply to: Re: Flaws of the Dr. Ornish' study (links enabled) posted by link enabler on June 21, 2002 at 09:33:29:

nmi

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Re: Flaws of the Dr. Ornish' study (Archive in atherosclerosis.)

Posted by Walt Stoll on June 22, 2002 at 07:39:06:

In Reply to: Flaws of the Dr. Ornish' study posted by R. on June 21, 2002 at 03:53:07:

Thanks, R.

The biggest flaw, in the process he unabashedly stole from Pritikin, is that he has altered Pritikin's process to try to make it more palatable to the AMA. This was done for promotion purposes only and so far has been very successful. After all Pritikin was not a member of the "union"; sig: was not an MD. Ornish IS an MD.

Unfortunately, Ornish's main change was a 15% fat diet rather than a 10% diet and so is not nearly as effective.

Hope this helps.

Walt



Opposing view

Posted by Fluffy on June 24, 2002 at 14:42:23:

In Reply to: Flaws of the Dr. Ornish' study posted by R. on June 21, 2002 at 03:53:07:

...why bother millions of people with a diet that only rabbits may find tolerable?
As a Belgian Hare, I strongly object to that last statement as derogatory towards my species. So you think you have it all figured out eh? Thought you could publish this crap behind my back? You forgot I have eyes in the side of my head, pal. Thought I wouldn't hear about it huh? Have you seen my ears buster? Well, mister, I've learned about this so-called diet and I think you wouldn't know rabbit food if you hopped over it. Scientific study indeed! Since when do rabbits eat vegetarian samosas and bean curd? You may catch some of those Flemish Giant rabbits gorging themselves on that poison but not me, mister! The trouble with you humans is you don't know what's good for ya. Now take me, for example. I mainly eat wood ashes, dung-seasoned timothy hay, my hair, and sometimes my own young. And do I have atherosclerosis? Look at these legs! Not a spider vein in sight! Forget the Ornish diet, you all need to look into the Fluffy diet. Now as far as exercise goes, I admit I do get my share, what with escaping predators and multiplying and all, but most of it comes in short bursts followed by a half hour of compulsive grooming. And as for smoking, I can't even afford to smoke a quick one after sex because the way I multiply, brother, I'd kill a carton a day easy! Now when it comes to stress management, all you have to learn how to do is freeze. That and how to suck it in when you go to the vet so she can't damage the giggleberries. Here is my Wellness stoll:


Get that down and your life expectancy will top 5 years, just like me!
--Fluffy


Re: Hahaha Great response!! still laughing nmi

Posted by BarbaraN on June 24, 2002 at 15:31:52:

In Reply to: Opposing view posted by Fluffy on June 24, 2002 at 14:42:23:

nmi

Follow Ups:


Problem with vegetarians vs. non-vegetarian studies

Posted by Lincoln on June 24, 2002 at 19:19:42:

In Reply to: Re: Flaws of the Dr. Ornish' study posted by thessa on June 21, 2002 at 07:57:28:

1. ANY change to the typical (non-vegetarian) American diet constitutes an improvement. The American diet is that abysmal.

2. It is possible that vegetarians are more likely to take care of their health in other, non-diet ways. For example, in the long-term Nurses Study, it has recently been shown that people who get prescriptions filled are more likely to to take care of other aspects of their health than people who don't, REGARDLESS OF THE PURPOSE OF THE PRESCRIPTION! In other words, it's theoretically possible to 'discover' that anti-fungal toe-nail cream helps prevent heart disease! Well, of course toe-nail cream doesn't cure heart disease, but people who take care of their toe-nails might be more likely to take care of their heart than people who let their toe-nails go to rot.



Re: Problem with vegetarians vs. non-vegetarian studies

Posted by Walt Stoll on June 25, 2002 at 10:20:36:

In Reply to: Problem with vegetarians vs. non-vegetarian studies posted by Lincoln on June 24, 2002 at 19:19:42:

Thanks, Lincoln!

Walt

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Re: Problem with vegetarians vs. non-vegetarian studies

Posted by R. on June 26, 2002 at 16:04:08:

In Reply to: Problem with vegetarians vs. non-vegetarian studies posted by Lincoln on June 24, 2002 at 19:19:42:

Your second point was exactly my point regarding the "nut" study that "discovered" that eating nuts at least twice a week *may be* very beneficial. And sure enough, the conclusion of the report was a definite "eat your nuts" recommendation.

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Re: Flaws of the Dr. Ornish' study (Archive in atherosclerosis.)

Posted by R. on July 16, 2002 at 03:49:00:

In Reply to: Re: Flaws of the Dr. Ornish' study (Archive in atherosclerosis.) posted by Walt Stoll on June 22, 2002 at 07:39:06:

Actually, Ornish's "therapeutic" diet limits fat to 10%. And his preventive diet is 15%.



Re: Flaws of the Dr. Ornish' study (Archive in atherosclerosis.)

Posted by Walt Stoll on July 17, 2002 at 11:24:35:

In Reply to: Re: Flaws of the Dr. Ornish' study (Archive in atherosclerosis.) posted by R. on July 16, 2002 at 03:49:00:

Thanks, R.

I will have to go back and re-read this since I have apparently misread it. If this is true he is right EXACTLY with Pritikin and still does not give him credit for teaching this 30 years earlier.

Namaste`

Walt

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