Tag Archives: Low Fat Diet

Is Dean Ornish’s Lifestyle Program “Scientifically Proven To Undo (Reverse) Heart Disease?”

Supporters of vegetarian/ultra low fat diets like to claim that there is solid scientific evidence of the cardiovascular benefits of their chosen diets.

To buttress these claims they will cite the studies of Esseslystn, Pritikin and Ornish.

I’ve previously discussed the bad science underlying the programs of Esselsystn and Pritikin but have only briefly touched on the inadequacy of Dean Ornish’s studies.

The Ornish website proclaims that their program is the first program “scientifically proven to undo (reverse) heart disease.” That’s a huge claim. If it were true, wouldn’t the Dietary Guidelines for Americans, the American Heart Association, and most cardiologists and nutrition experts be recommending it?

Who Is 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 Ornish’s Program 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. You can read the details of the one year results here.and the five year results here.

There are  so many limitations to this study that the mind boggles that it was published in a reputable journal.

-Recruitment of patients. 

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?

-The Intervention.

The experimental patients received “intensive lifestyle changes (<10% fat whole foods vegetarian diet, aerobic exercise, stress management training, smoking cessation, group psychosocial support).
The control group had none of the above.

Needless to say this was not blinded and the researchers definitely knew which patients were in which group.

Control-group patients were “not asked to make lifestyle changes, although they were free to do so.”

There is very little known about the 20 slackers in the control group. I can’t find basic information about them-crucial things like how many smoked or quit smoking or how many were on statin drugs.

-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 (see here) which allow measurement of total atherosclerotic plaque burden.

Rather than burden the reader  with the details at this point I’ve included a discussion of this as an addendum.

-The Outcome

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.

I’ve gotten a lot of flack for humorously suggesting that Nathan Pritikin killed himself as a result of the austere no fat diet he consumed but the bottom line on any lifestyle change is both quality and quantity of life.

If you are miserable most days due to your rigid diet you might consider that life is no longer worth living

Ornish’s Lifestyle Intervention Is Not A Trial Of Diet …And Other Points

 

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/Esselstyn/Pritikin dietary 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.

Skeptically Yours,

-ACP

N.B.1 A recent paper on noninvasive assessment of atherosclerotic plaque has a great infographic which shows how coronary artery disease progresses and how and when in the progression various imaging modalities are able to detect plaque:

I’ve inserted a vertical red arrow which shows how IVUS detects very early atheroma whereas angiography (ICA, green line) only detects later plaque when it has started protruding into the lumen of the artery.

The paper notes that “Intravascular ultrasound (IVUS)  constitutes the current gold standard for plaque quantification. Multiple studies using IVUS and other techniques have revealed a robust relation between statin therapy and plaque regression. In the ASTEROID trial coronary atheroma volume regressed by 6.8% during 24 months of high-intensity lipid therapy. A meta-analysis of IVUS trials including 7864 patients showed an association between plaque regression and decreased cardiovascular events.”

While I believe Ornish started off as a legitimate scientist several authors have pointed out that he has joined the ranks of pseudoscientific practiioners.

Here’s one analysis from Science Blogs :

In the end, the problem is that Dr. Ornish has yoked his science to advocates of pseudoscience, such as Deepak Chopra and Rustum Roy. Why he’s done this, I don’t know. The reason could be common philosophy. It could be expedience. It could be any number of things. By doing so, however, Dr. Ornish has made a Faustian deal with the devil that may give him short-term notoriety now but virtually guarantees serious problems with his ultimately being taken seriously scientifically, as he is tainted by this association. Let me yet again reemphasize that this relabeling of diet, exercise, and lifestyle as somehow being “alternative” is nothing more than a Trojan Horse. Inside the horse is a whole lot of woo, pseudoscience and quackery such as homepathy, reiki, Hoxsey therapy, acid-base pseudoscience, Hulda Clark’s “zapper,” and many others,

Low-Fat Versus Low-Carb Diet: DIETFITS Show Both Can Work If They Are “Healthy”

In the ongoing nutritional war between adherents of low-fat and low-carb diets, the skeptical cardiologist has generally weighed in on the side of lower carbs for weight loss and cardiovascular health.

I’ve questioned the vilification of saturated fat and emphasized the dangers of added sugar. I’ve even dabbled in nutritional ketosis.

The science in  nutrition is gradually advancing and the DIETFITS study recently published in JAMA is a welcome addition.

DIETFITS is a  really well done study which provides important insights into three huge questions about optimal diet:

  1. Should we choose a low-fat or a  low-carb diet for  weight loss and cardiovascular health?
  2. Do baseline insulin dynamics predict who will respond to low-fat versus low-carb diet?
  3. Can we predict who will respond to low-fat versus low-carb by genetic testing?

The Details Of DIETFITS

Stanford investigators recruited 609 San Francisco area individuals between the ages of 18 to 50 years with BMI of 28 to 40  and randomized them to a “healthy” low-fat diet or a “healthy” low-carb diet.

During the first 8 weeks of the study, low-fat participants were instructed to reduce fat consumption to <20 gm/ day while the low carb participants were instructed to reduce digestible carbohydrate to <20 gms/day.

Then individuals were allowed to add back fats or carbs back to their diets in increments of 5 to 15 g/d per week until “they reached the lowest level of intake they believed could be maintained indefinitely.”  Importantly no explicit instructions for energy restriction were given.

The “healthy” instructions for both groups were as follows

  1. maximize vegetable intake
  2. minimize intake of added sugar, refined flours and trans-fats
  3. focus on whole foods that are minimally processed, nutrient dense and prepared at home whenever possible

Dietfits Outcomes-Diet And Weight

Major findings

  1. Total energy intake was reduced by 500-600 kcal/d for both groups
  2. The low-fat vs the low-carb intake at 12 months was 48% versus 30% for carbs, 29 vs 43% for fat and 21 vs 23% for protein.
  3. Mean 12 months weight change was -5.3 kg for low-fat vs 6-6.0 kg for low-carb which was not significantly different
  4. There was no difference between groups in body fat percentage or waist circumference
  5. Both diets improved lipid profiles and lowered blood pressure, insulin and glucose levels
  6. LDL (bad cholesterol) declined more in the low-fat group whereas HDL (good cholesterol) increased more and triglycerides declined more in the low-carb group.

Thus both diets were successful for weight loss and both improved risk markers for cardiovascular disease after a year.

DIETFITS- Can Genes and Insulin resistance Predict Best Diet?

Surprisingly, the study found no significant diet-genotype interaction and no diet-insulin secretion interaction with weight loss.

This means that they could not predict (as many believed based on earlier studies) who will benefit from a low carb diet based on either currently available genetic testing or a generally accepted measure of insulin resistance.

As the authors point out, these findings “highlight the importance of conducting large, appropriately powered trials such as DIETFITS for validating early exploratory analyses.”

DIETFITS-Perspectives

As you can imagine this study has led to quite an uproar and backlash from dedicated combatants in the macronutrient wars.

A reasoned summary and response from Andreas Eenfeldt, a low carb proponent can be found on his excellent low carb/keto Diet Doctor site here.

Eenfeldt concludes

If I’m allowed to speculate, the reason that we did not see any major additional benefit from low carb in this study is that the groups ended up so similar when it came to bad carbs. The low-fat group ended up eating fewer carbs too (!) and significantly less sugar, while the low-carb group ended with a somewhat weak low-carb diet, reporting 130 grams of carbs per day.

Eenfeldt emphasizes that low-fat diets never “win” these macronutrient dietary skirmishes:

On the whole, this study adds to the 57 earlier studies (RCTs) comparing low carb and low fat for weight loss.

From a standing of 29 wins for low carb, zero for low fat and 28 draws, we now have 29 wins for low carb and 29 draws. The wins for low fat stay at zero.

Larry Husten at Cardiobrief.org in his analysis of the study quotes a number of experts including Gary Taubes, the low carb pioneering journalist

Taubes speculates “that the weight loss may have been similar not because any diet works if you stick with it and cut calories (one possible interpretation) but because of what these diets had in common — avoid sugar, refined grains, processed foods. Whether the low-carb arm would have done even better had Gardner kept their carbohydrates low is something this study can’t say. (And Ornish [low-fat diet proponent] would probably say the same thing about fat consumption.)”

The low-fat or vegan disciples seem to have had a muted response to this study. I can’t find anything from John McDougal , Dean Ornish, Caldwell Esselstyn or Joel Fuhrman.

Readers feel free to leave comments which  link to relevant analysis from the low-fat proponents.

Dietfits-Perspective Of The Participants

Julia Volluz at Vox wrote a fascinating piece recently which involved interviewing some of the participants in this study.

She points out that although the average DIETFITS participant lost over 10 pounds, “Some people lost more than 60 pounds, and others gained more than 20 during the year.”

LOW_FAT_LOW_CARBS_DIETS1__1_

She obtained permission from the lead author, Christopher Gardner  and interviewed  “Dawn, Denis, Elizabeth*, and Todd — two low-fat dieters and two low-carb dieters — about their experiences of succeeding or faltering in trying to slim down”

LOW_FAT_LOW_CARBS_DIETS1

I highly recommend reading the entire article for details but Volluz concludes

And that leads us to one of the burning mysteries of diets: how to explain why some people fail where others succeed — or the extreme variation in responses. Right now, science doesn’t have compelling answers, but the unifying theme from the four study participants should be instructive: The particulars of their diets — how many carbs or how much fat they were eating — were almost afterthoughts. Instead, it was their jobs, life circumstances, and where they lived that nudged them toward better health or crashing.

DIETFITS-Importance of “Healthy” Diet

Most likely the success of both of these diets is due to the instruction that both groups received on following a “healthy” diet. This guidance is remarkably similar to what I advocate and is something that combatants in the diet wars ranging from paleo to vegan can agree on.

The JAMA paper only provides the description I listed above but Volluz adds that participants were instructed to:

… focus on whole, real foods that were mostly prepared at home when possible, and specifically included as many vegetables as possible, every day … choose lean grass-fed and pasture-raised animal foods as well as sustainable fish ... eliminate, as much as possible, processed food products, including those with added sugars, refined white flour products, or trans-fats … prepare as much of their own food as possible. …

Indeed, if you want to see a very detailed description of the instructional process for participants check out the very detailed description of the methods here.

Yours in Health,

-ACP

N.B. I was searching for a reasoned response to this study from the low fat camp and to my surprise came across this fascinating video featuring the lead author of the study, Christopher Gardner, on (no fat/vegan) John McDougal’s YouTube site. Gardner is clearly on the side of sustainable, local , ethical food consumption but to his credit, his research , publications and comments on DIETFITS don’t reveal this.

Scintillating Findings From New Orleans: Low Carb Diet Is Better than Low Fat for Losing Weight and Preventing Heart Disease

The SC and the Significant Other of the SC at Commander's Palace following an investigation of shrimp and grits.
The SC and the Significant Other of the SC at Commander’s Palace following an investigation of shrimp and grits.

The Skeptical Cardiologist is in New Orleans this weekend on a dedicated quest to research low carb diets.

The low fat diets recommended by government guidelines and national organizations like the American Heart Association don’t help most individuals lose weight and they don’t lower  the risk of heart disease. It’s very hard to understand why these are still promulgated by these organizations.

Some diets, such as the Atkins, South Beach and Paleo diets, advocate very low carbohydrate consumption and have helped many successfully lose weight.  However, due to the high fat in such diets, there has been concern about their overall effect on  cholesterol levels and heart disease.

A new study published in the Annals of Internal Medicine addressed the question of which of these dietary  approaches is best. Researchers at Tulane University (located inNew Orleans!)  randomly divided   148 obese (BMI>30) men and women (88% were women and 51% were black) into two  groups: a low-carbohydrate group that was encouraged to consume no more than 40 grams of carbohydrates  per day (the amount of two slices of  bread), and a low-fat group, which was encouraged to consume less than 30 percent of their calories from fat and 55 percent from carbohydrates (based on the National Education Cholesterol Program guidelines).

Interestingly neither group was instructed to lower their overall calorie consumption and both groups were instructed NOT to change their overall physical activity level (the researchers were trying to minimize factors effecting their results other than the percentage of fat/carbs).

The funding source for the study was the National Institutes of Health so we can consider the study unbiased by industry.

After 12 months, the low-fat group had lost 1.8 kg (2.2lbs=1kg) and the low-carb group had lost 5.3 kg.

The low-carb group had lost 8 pounds more, a difference that was highly  statistically significant (p<.001).

In addition, in the low-carb group fat mass had declined by 1.2% whereas it had risen by 0.3% in the low-fat group.

In other words, the low-carb group was losing body fat but the low-fat group was just losing lean body mass.

My patients, like most Americans, have had the lie that fat consumption causes obesity and contributes to fatty plaques in their arteries drummed into their heads for decades and fear low-carb diets because of concerns that they will cause their cholesterol levels to rise and increase their risk of heart disease.

This new study, however, showed that the low-carb diet (with almost double the amount of saturated fat consumed compared to low-fat diet) actually improved the subjects’ heart risk profile.

Low Carb Diet Improves Cardiac Risk Profile

At 12 months, there was no difference in the total or LDL (bad cholesterol) levels between the two groups. However, the good (HDL) cholesterol had significantly increased in the low-carb group causing a decrease in the ration of total to HDL cholesterol. The low-fat group had no increase in HDL. Triglycerides dropped in both groups but significantly more in the low-carb group.

Atherosclerosis is not just related to the cholesterol profile as I have discussed here,  but it is a complex process involving multiple factors, including inflammation.  A simple blood test, the C-reactive protein or CRP tracks inflammation. The CRP dropped by 6.7 nmol/L in the low-carb group and rose by 8.6 nm/L in the low-fat group. Lower CRP levels have been associated with lower risk of cardiovascular events in multiple studies.

This was a small study (but actually one of the largest prospective dietary studies available) but really well done.

The major take home points are as follows:

  1. Low-carb diets for many are a very effective weight loss approach
  2. Low-carb diets, even with their higher saturated and overall  do not adversely effect the cholesterol profile or increase risk of heart disease.
  3. This study suggests that low-carb diets improve good cholesterol, lower inflammation and are likely, therefore, long term to reduce the risk of heart attacks and strokes.

Realistic Dietary Approaches

I have found the extremely low-carb diets such as Atkins to be very hard for my patients to follow long term.  Some modification of  the strict limits on carb consumption are necessary I think to make diets interesting and healthy.

Although the goal of this study was to have the low-carb group consume less than 40 grams, the average carb consumption was 93 grams at 6 months and 127 grams at 12 months, a much more sustainable level of carb intake.

The first and most important thing anyone can do if they  want to lose weight and improve their cardiovascular risk profile is eliminate added sugar from their diet.

Sugar-sweetened beverages are an easy first step. But equally important is avoiding foods masquerading as healthy due to their low fat content. Low-fat yogurt and smoothies, for example, are loaded with empty sugar calories. You are much better off consuming the full fat varieties as I have pointed out here.

This is the Skeptical Cardiologist signing off from beautiful New Orleans where my next investigation will be on the cardiovascular consequences of crawfish étouffée plus dixieland jazz.