Editor's Note: Our April 22 article elicited a lengthy response from Dean Ornish, which we publish here, along with a rebuttal from Melinda Wenner Moyer.

Last month, an op–ed in The New York Times argued that high-protein and high-fat diets are to blame for America’s ever-growing waistline and incidence of chronic disease. The author, Dean Ornish, founder of the nonprofit Preventive Medicine Research Institute, is no newcomer to these nutrition debates. For 37 years he has been touting the benefits of very low-fat, high-carbohydrate, vegetarian diets for preventing and reversing heart disease. But the research he cites to back up his op–ed claims is tenuous at best. Nutrition is complex but there is little evidence our country’s worsening metabolic ills are the fault of protein or fat. If anything, our attempts to eat less fat in recent decades have made things worse.

Ornish begins his piece with a misleading statistic. Despite being told to eat less fat, he says, Americans have been doing the opposite: They have “actually consumed 67 percent more added fat, 39 percent more sugar and 41 percent more meat in 2000 than they had in 1950 and 24.5 percent more calories than they had in 1970.” Yes, Americans have been eating more fat, sugar and meat, but we have also been eating more vegetables and fruits (pdf)—because we have been eating more of everything.

What’s more relevant to the discussion is this fact: During the time in which the prevalence of obesity in the U.S. nearly tripled, the percentage of calories Americans consumed from protein and fat actually dropped whereas the percentage of calories Americans ingested from carbohydrates—one of the nutrient groups Ornish says we should eat more of—increased. Could it be that our attempts to reduce fat have in fact been part of the problem? Some scientists think so. “I believe the low-fat message promoted the obesity epidemic,” says Lyn Steffen, a nutritional epidemiologist at the University of Minnesota School of Public Health. That’s in part because when we cut out fat, we began eating foods that were worse for us.

Ornish goes to argue that protein and saturated fat increase the risk of mortality and chronic disease. As evidence for these causal claims, he cites a handful of observational studies. He should know better. These types of studies—which might report that people who eat a lot of animal protein tend to develop higher rates of disease—“only look at association, not causation,” explains Christopher Gardner, a nutrition scientist at the Stanford Prevention Research Center. They should not be used to make claims about cause and effect; doing so is considered by nutrition scientists to be “inappropriate” and “misleading.” The reason: People who eat a lot of animal protein often make other lifestyle choices that increase their disease risk, and although researchers try to make statistical adjustments to control for these “confounding variables,” as they’re called, it’s a very imperfect science. Other large observational studies have found that diets high in fat and protein are not associated with disease and may even protect against it. The point is, it’s possible to cherry-pick observational studies to support almost any nutritional argument.

Randomized controlled clinical trials, although certainly not perfect, are better tools for chipping away at causality, and they suggest that protein and fat don’t deserve to be demonized. In a 2007 clinical trial led by Gardner researchers randomly assigned 311 individuals to four groups: One group was assigned the high-fat, high-protein and low-carbohydrate Atkins diet; the second was assigned Ornish’s very low-fat vegetarian diet, which requires consuming fewer than 10 percent of calories from fat; the third was assigned the Zone diet, which aims for a 40/30/30 percent distribution of carbohydrate, protein and fat; and the fourth was assigned the high-carbohydrate, low–saturated fat LEARN (for: lifestyle, exercise, attitudes, relationships, nutrition) diet. The participants all had trouble adhering to their regimens, but all lost about the same statistically significant amounts of weight, and when compared head to head, the Atkins dieters saw greater improvements in blood pressure and HDL cholesterol than the Ornish dieters did.

The recent multicenter PREDIMED trial also supports the notion that fat can be good rather than bad. It found that individuals assigned to eat high-fat (41 percent calories from fat), Mediterranean-style diets for nearly five years were about 30 percent less likely to experience serious heart-related problems compared with individuals who were told to avoid fat. (All groups consumed about the same amount of protein.) Protein, too, doesn’t look so evil when one considers the 2010 trial published in The New England Journal of Medicine that found individuals who had recently lost weight were more likely to keep it off if they ate more protein, along with the 2005 OmniHeart trial that reported individuals who substituted either protein or monounsaturated fat for some of their carbohydrates reduced their cardiovascular risk factors compared with individuals who did not.

The other problem with Ornish’s antiprotein stance is that he lumps all animal proteins together. For instance, he wrote that animal proteins have been associated with higher disease and mortality risks in observational studies. But “Ornish is conflating hot dogs and pepperoni with fresh, unprocessed meats,” says Lydia Bazzano, professor of nutrition and epidemiology at Tulane University School of Public Health and Tropical Medicine, “and there’s a big difference between them.” A 2010 systematic review and meta-analysis of 20 studies found consumption of processed meat was associated with an increased risk of diabetes and heart disease but eating unprocessed red meat was not. A 2014 meta-analysis similarly reported much higher mortality risks associated with processed meat compared with red meat consumption and found no problems associated with white meat. The March 2014 study that Ornish cites as finding “a 75 percent increase in premature deaths from all causes and a 400 percent increase in deaths from cancer and type 2 diabetes among heavy consumers of animal protein under the age of 65,” also did not distinguish between types of animal protein. And it is worth noting that among people in the study over 65, heavy consumption of animal protein actually protected against cancer and mortality. (Also: the heavy protein consumers in the study were consuming nearly 30 percent more protein than the average American does.) “Whole foods—such as whole grain products and fruits and veggies—are healthy, but I think that dairy products, fish and lean cuts of meat or poultry can also be part of a healthy diet,” Steffen says.

So there’s little evidence to suggest that we need to avoid protein and fat. But what about the claims Ornish makes about the success of his own diet—do they hold up to scrutiny? Not exactly. His famous 1990 Lifestyle Heart trial involved a total of 48 patients with heart disease. Twenty-eight were assigned to his low-fat, plant-based diet and 20 were given usual cardiac care. After one year those following his diet were more likely to see a regression in their atherosclerosis.

But here’s the thing: The patients who followed his diet also quit smoking, started exercising and attended stress management training. The people in the control group were told to do none of these things. It’s hardly surprising that quitting smoking, exercising, reducing stress and dieting—when done together—improves heart health. But fact that the participants were making all of these lifestyle changes means that we cannot make any inferences about the effect of the diet alone.

So when Ornish wrote in his op–ed that “for reversing disease, a whole-foods, plant-based diet seems to be necessary,” he is incorrect. It’s possible that quitting smoking, exercising and stress management, without the dieting, would have had the same effect—but we don’t know; it’s also possible that his diet alone would not reverse heart disease symptoms. Again, we don’t know because his studies have not been designed in a way that can tell us anything about the effect of his diet alone. There’s also another issue to consider: Although Ornish emphasizes that his diet is low in fat and animal protein, it also eliminates refined carbohydrates. If his diet works—and again, we don’t know for sure that it does—is that because it reduces protein or fat or refined carbohydrates?

The point here is not that Ornish’s diet—a low-fat, whole food, plant-based approach—is necessarily bad. It’s almost certainly healthier than the highly processed, refined-carbohydrate-rich diet most Americans consume today. But Ornish’s arguments against protein and fat are weak, simplistic and, in a way, irrelevant. A food or nutrient can be healthy without requiring that all other foods or nutrients be unhealthy. And categorizing entire nutrient groups as “good” or “bad” is facile. “It’s hard to move the science forward when there are so many stakeholders who say ‘this is the right diet and no other one could possibly be right,’” Bazzano says. Plus, discouraging the intake of entire macronutrient groups can backfire. When people dutifully cut down on fat in the 1980s and 1990s, they replaced much of it with high-sugar and high-calorie processed foods (think: Snackwell’s). If we start fearing protein, too, what will we fill our plates with instead? History tells us it’s not going to be spinach.

Dean Ornish Responds

I don’t usually respond to ad hominem attacks, but when I read Melinda Wenner Moyer’s article “Why Almost Everything Dean Ornish Says about Nutrition Is Wrong,” I felt a need to set the record straight. The title is confusing and potentially harmful to many readers.

For the past 37 years my colleagues and I at the nonprofit Preventive Medicine Research Institute, in collaboration with leading scientists and medical institutions, have published a series of randomized controlled trials and demonstration projects showing that comprehensive lifestyle changes may slow, stop and often reverse the progression of many chronic diseases. These include a whole foods, plant-based diet low in refined carbohydrates, moderate exercise, stress management techniques and social support.

These studies have been conducted with well-respected collaborators, published in the leading peer-reviewed journals, and presented at the most credible scientific meetings. These include JAMA The Journal of the American Medical Association, The Lancet, Proceedings of the National Academy of Sciences, The Lancet Oncology, The New England Journal of Medicine, The American Journal of Cardiology and others.

I have presented these research findings on several occasions at the annual scientific meetings of the American Heart Association, American College of Cardiology, American Dietetic Association (now the Academy of Nutrition and Dietetics), the Institute of Medicine of the National Academies and many others.

On August 12, 2010, after 16 years of review, the Centers for Medicare & Medicaid Services began providing Medicare coverage for my intensive lifestyle program for reversing heart disease under a new benefit category, “intensive cardiac rehabilitation.” Many insurance companies are also providing coverage. My colleagues and I have been training and certifying teams of health care professionals at leading hospitals, clinics and health systems in this lifestyle program for reversing heart disease.

Earlier this year a panel of experts from U.S. News & World Report rated the “Ornish Diet” as the number-one diet for heart health for the fifth year in a row (that is, all five years they have been doing rankings).

When Moyer accuses me of having inadequate scientific evidence to support my statements, I must respectfully and strongly disagree. Let’s check the facts:

Headline: Why Almost Everything Dean Ornish Says about Nutrition Is Wrong

Provocative but incorrect.

Subhead: When it comes to good eating habits, protein and fat are not your dietary enemies

Her article begins with a gross distortion of what I believe. It's the type of protein, fat and carbohydrates that matters. The diet I recommend is low in refined carbohydrates and low in harmful fats (including trans fats, hydrogenated fats and some saturated fats) and low in animal protein (particularly red meat) but includes beneficial fats (including omega-3 fatty acids), good carbs (including fruits, vegetables, whole grains, legumes and soy in their natural, unrefined forms) and good proteins (predominantly plant-based). This was clearly stated in my New York Times op–ed:

“An optimal diet for preventing disease is a whole-foods, plant-based diet that is naturally low in animal protein, harmful fats and refined carbohydrates. What that means in practice is little or no red meat; mostly vegetables, fruits, whole grains, legumes and soy products in their natural forms; very few simple and refined carbohydrates such as sugar and white flour; and sufficient “good fats” such as fish oil or flax oil, seeds and nuts. A healthful diet should be low in “bad fats,” meaning trans fats, saturated fats and hydrogenated fats. Finally, we need more quality and less quantity.”

Moyer wrote: Nutrition is complex but there is little evidence our country’s worsening metabolic ills are the fault of protein or fat. If anything, our attempts to eat less fat in recent decades have made things worse. Ornish begins his piece with a misleading statistic. Despite being told to eat less fat, he says, Americans have been doing the opposite: They have “actually consumed 67 percent more added fat, 39 percent more sugar and 41 percent more meat in 2000 than they had in 1950 and 24.5 percent more calories than they had in 1970.” Yes, Americans have been eating more fat, sugar and meat, but we have also been eating more vegetables and fruits—because we have been eating more of everything.

Well, that’s the point—we’re not fat because we’re eating too little fat; we’re fat because we’re eating too much of everything.

Other nonscientist, nonphysician writers have also been saying that Americans have been told to eat less fat—“We’re eating less fat, we’re fatter than ever, so we’ve been given bad advice. Eat more meat, butter and eggs, they’re good for you (prominently pictured on the cover of their books), all those experts have been wrong.” This has been repeated so often in the echo chamber of modern media that it’s become a meme.

But it’s not true. As I wrote about in my op–ed, according to the U.S. Department of Agriculture (pdf), every decade since 1950 Americans actually have been eating more fat, more sweeteners, more meat and more calories.

What’s more relevant to the discussion is this fact: During the time in which the prevalence of obesity in the U.S. nearly tripled, the percentage of calories Americans consumed from protein and fat actually dropped whereas the percentage of calories Americans ingested from carbohydrates—one of the nutrient groups Ornish says we should eat more of—increased. Could it be that our attempts to reduce fat have in fact been part of the problem? Some scientists think so. “I believe the low-fat message promoted the obesity epidemic,” says Lyn Steffen, a nutritional epidemiologist at the University of Minnesota School of Public Health. That’s in part because when we cut out fat, we began eating foods that were worse for us.

First, she’s again perpetuating the myth that “…when we cut out fat, we began eating foods that were worse for us.” As the USDA data show, we’re eating more fat, not less.

Second, as I made clear in the op–ed as well as in my books and journal articles, the diet I recommend is low in refined carbohydrates and high in “good carbs” such as fruits, vegetables, whole grains, legumes and soy products in their natural, unrefined forms (which tend to have low glycemic loads). She completely misrepresents my recommendations: “…carbohydrates—one of the nutrient groups Ornish says we should eat more of—increased.” I’ve always recommended that people limit their consumption of sugar and other refined carbohydrates.

Third, she’s confusing the USDA data (which I cited in my op–ed) and the National Health and Nutrition Examination Survey (NHANES) data (which looked at the percentage of calories). The USDA tracks changes in consumption of the entire food supply. In contrast, the NHANES data is from surveying only a small sample of people nationwide, so it’s less reliable. Sample sizes ranged from 1,730 men and 2,003 women in NHANES 1999 to 2000 to 6,630 men and 7,537 women in NHANES III. Since the U.S. population last year was 322 million people, this represents only 0.000044% of the population, and different people are surveyed each year. This is why I use the USDA data (which tracks consumption of the entire food supply, not just a tiny sample).

But even if the NHANES data are accurate, they show Americans are eating more fat than ever and even more refined carbohydrates than ever. That only supports my thesis, because I recommend that people eat less harmful fats and fewer refined carbohydrates. The decrease in the percentage of calories from fat during the period 1971 to 1991 is attributed to an increase in total calories consumed; absolute fat intake in grams actually increased.

Fourth, the patients in our randomized controlled trial (JAMA. 1998) showed an average reduction of 24 pounds in the first year. In a larger study of almost 3,000 patients who went through my lifestyle program in 24 hospitals and clinics, BMI (body mass index) decreased by 6.6 percent. In other words, the diet I recommend causes weight loss, not weight gain. Pres. Bill Clinton is one of the more public examples of this, having lost and kept off more than 20 pounds since following the whole foods, plant-based diet I recommended for him five years ago (including salmon once a week).

Ornish goes to argue that protein and saturated fat increase the risk of mortality and chronic disease. As evidence for these causal claims, he cites a handful of observational studies. He should know better. These types of studies—which might report that people who eat a lot of animal protein tend to develop higher rates of disease—“only look at association, not causation,” explains Christopher Gardner, a nutrition scientist at the Stanford Prevention Research Center. They should not be used to make claims about cause and effect; doing so is considered by nutrition scientists to be “inappropriate” and “misleading.” The reason: People who eat a lot of animal protein often make other lifestyle choices that increase their disease risk, and although researchers try to make statistical adjustments to control for these “confounding variables,” as they’re called, it’s a very imperfect science. Other large observational studies have found that diets high in fat and protein are not associated with disease and may even protect against it. The point is, it’s possible to cherry-pick observational studies to support almost any nutritional argument.

First, I cited several large-scale studies from many different investigators, all of which showed that a diet high in red meat increases the risk of premature death from virtually all causes, even when adjusting for confounding variables. I’m not cherry-picking data; I’m looking at the preponderance of evidence from many studies by leading investigators such as those at Harvard School of Public Health.

Second, another “big fat lie” that has been repeated so often it’s becoming a meme is that there is not enough good science to inform us about an optimal way of eating. Believing this, many people are throwing up their hands, exasperated, saying, “These damn doctors can’t make up their minds—to hell with them, I’ll eat whatever I want,” when there is actually an emerging consensus among scientists and physicians who do research in nutrition about what constitutes an optimal way of eating. Although we always need more research, there is enough science now to guide us. Moyer’s article only adds to that confusion.

Randomized controlled clinical trials, although certainly not perfect, are better tools for chipping away at causality, and they suggest that protein and fat don’t deserve to be demonized. In a 2007 clinical trial led by Gardner researchers randomly assigned 311 individuals to four groups: One group was assigned the high-fat, high-protein and low-carbohydrate Atkins diet; the second was assigned Ornish’s very low-fat vegetarian diet, which requires consuming fewer than 10 percent of calories from fat; the third was assigned the Zone diet, which aims for a 40/30/30 percent distribution of carbohydrate, protein and fat; and the fourth was assigned the high-carbohydrate, low–saturated fat LEARN (for: lifestyle, exercise, attitudes, relationships, nutrition) diet. The participants all had trouble adhering to their regimens, but all lost about the same statistically significant amounts of weight, and when compared head to head, the Atkins dieters saw greater improvements in blood pressure and HDL cholesterol than the Ornish dieters did.

First, in this study, JAMA published a retraction of one of the main conclusions of this study by led by Christopher Gardner, which initially claimed that people lost more weight on the Atkins diet than on the diet I recommend, which turned out to be false (JAMA. 2007 Jul 11;298(2):178).This says something important about the quality of that research.

Second, there was no statistically significant difference in either systolic blood pressure or diastolic blood pressure after one year in comparing the groups. In contrast, there was a statistically significant reduction in LDL-cholesterol in the Ornish group but not in the Atkins group after one year.

Third, it is a common misconception that anything that raises HDL is beneficial and anything that lowers it is not. This is not true, as I wrote about years ago in my Newsweek column. In our randomized controlled Lifestyle Heart Trial, HDL cholesterol did not increase but patients showed regression of coronary atherosclerosis after one year, even more improvement after five years, and a 300 percent improvement in myocardial perfusion (blood flow to the heart) as measured by cardiac PET scans. HDL is important only to the extent that it affects atherosclerosis and myocardial perfusion, it is not a disease.

Fourth, the Gardner study did not really test very much of anything, other than it’s hard for many people to change their diets—any diet—from just reading a book. Adherence in his study to each of the diets was only 20 to 30 percent after one year, so it’s hard to make any conclusions at all.

Part of the problem in this and other studies that compare weight loss in low-fat versus low-carb diets (which is the wrong question anyway, because it’s the type of fats and carbs) is that adherence to different diets is often suboptimal, so it’s hard to make meaningful comparisons.

To address this issue, a recent National Institutes of Health study that I cited in my op–ed put people in a metabolic ward where they could actually control what people were eating and then measured the effects. According to the lead author, "Calorie for calorie, reducing dietary fat results in more body fat loss than reducing dietary carbohydrate when men and women with obesity have their food intake strictly controlled. Compared to the reduced carbohydrate diet, the reduced fat diet led to a roughly 67 percent greater body fat loss."

The recent multicenter PREDIMED trial also supports the notion that fat can be good rather than bad. It found that individuals assigned to eat high-fat (41 percent calories from fat), Mediterranean-style diets for nearly five years were about 30 percent less likely to experience serious heart-related problems compared with individuals who were told to avoid fat. (All groups consumed about the same amount of protein.)

Below is my letter to the editor of The New England Journal of Medicine that they published about this study:

“The PREDIMED study is highly flawed. The control group did not follow a low-fat diet. This is not surprising, since researchers gave the control group little support in following this diet during much of the study. In the “low-fat” control group, total fat consumption decreased insignificantly from 39 to 37 percent (Table S7 in the Supplementary Appendix, available with the full text of the article by Estruch et al. at NEJM.org). This level of consumption is much higher than the level recommended in American Heart Association guidelines for a low-fat diet (<30 percent fat) or a diet that can reverse coronary heart disease (<10 percent fat). There was no significant reduction in the rates of heart attack, death from cardiovascular causes or death from any cause. The only significant reduction was in the rate of death from stroke (see Table 3 of the article).



“The conclusion of the study should be, ‘We found a significant reduction in the rate of stroke among those consuming a Mediterranean diet as compared with those who were not making any substantial changes in their diet.’ A Mediterranean diet is better than what most people are consuming; even better is a diet based on whole foods and plants that is low in fat (especially saturated and trans fat) and in refined carbohydrates while allowing for sufficient consumption of n–3 fatty acids.”

Protein, too, doesn’t look so evil when one considers the 2010 trial published in The New England Journal of Medicine that found individuals who had recently lost weight were more likely to keep it off if they ate more protein, along with the 2005 OmniHeart trial that reported individuals who substituted either protein or monounsaturated fat for some of their carbohydrates reduced their cardiovascular risk factors compared with individuals who did not.

I’ve never said that protein is “evil.” In my op–ed, I clearly stated that it’s better to consume plant-based proteins than animal-based proteins, especially red meat. I wrote:

For example, in the OmniHeart trial she cited, the group that was asked to consume 10 percent more protein emphasized plant proteins, not animal protein. And the 10 percent reduction in carbohydrate in the higher protein diet and the higher unsaturated fat diet was achieved by replacing some fruits with vegetables, reducing sweets and using smaller portions of refined grain products. All three diets reduced blood pressure, total and low-density lipoprotein cholesterol levels, and estimated coronary heart disease risk.

But the real issue is what happens to actual measures of heart disease, not just risk factors, which I will describe further on.

The other problem with Ornish’s antiprotein stance is that he lumps all animal proteins together. For instance, he wrote that animal proteins have been associated with higher disease and mortality risks in observational studies. But “Ornish is conflating hot dogs and pepperoni with fresh, unprocessed meats,” says Lydia Bazzano, professor of nutrition and epidemiology at Tulane University School of Public Health and Tropical Medicine, “and there’s a big difference between them.” A 2010 systematic review and meta-analysis of 20 studies found consumption of processed meat was associated with an increased risk of diabetes and heart disease but eating unprocessed red meat was not. A 2014 meta-analysis similarly reported much higher mortality risks associated with processed meat compared with red meat consumption and found no problems associated with white meat.

As Moyer indicates here, the 2014 meta-analysis showed higher mortality risks associated with both processed meat and unprocessed meats. The fact that processed meat is even worse for you than unprocessed meats does not change the fact that the risk of premature death from all causes is higher in those eating red meat than those who do not.

The fact that not all studies have shown this risk does not mean that it is not true. In doing large-scale studies in which people complete dietary surveys, there is often so much noise—especially in combining data in meta-analyses—that a type 2 error often occurs (that is, the noise obscures the ability to detect statistically significant differences).

In a study from Harvard School of Public Health they prospectively observed 37,698 men from the Health Professionals Follow-Up Study (1986–2008) and 83,644 women from the Nurses' Health Study (1980–2008) who were free of cardiovascular disease (CVD) and cancer at baseline. Diet was assessed by validated food frequency questionnaires and updated every four years.

They documented 23,926 deaths (including 5,910 CVD and 9,464 cancer deaths) during 2.96 million person-years of follow-up. After multivariate adjustment for major lifestyle and dietary risk factors, the pooled hazard ratio (HR) (95 percent CI) of total mortality for a one-serving-per-day increase was 1.13 (1.07–1.20) for unprocessed red meat and 1.20 (1.15–1.24) for processed red meat. The corresponding HRs (95 percent CIs) were 1.18 (1.13–1.23) and 1.21 (1.13–1.31) for CVD mortality and 1.10 (1.06–1.14) and 1.16 (1.09–1.23) for cancer mortality. The editor of JAMA Internal Medicine invited me to write an accompanying editorial for this study.

A related study by this group looked at 85,168 women and 44,548 men without heart disease, cancer or diabetes from the Nurses’ Health Study and the Health Professionals’ Follow-Up Study. They concluded, “A low-carbohydrate diet based on animal sources was associated with higher all-cause mortality in both men and women whereas a vegetable-based low-carbohydrate diet was associated with lower all-cause and cardiovascular disease mortality rates.” Another major research article studied 43,396 Swedish women over 15 years. It concluded that “low-carbohydrate/high-protein diets are associated with increased risk of cardiovascular diseases.”

I am not against all forms of animal protein. It may be worth noting that my most recent book, The Spectrum, featured a piece of salmon on the cover.

In assessing the health effects of different diets it’s important to measure the disease process itself, not just risk factors such as blood pressure and cholesterol levels. For example, an important article, published in The New England Journal of Medicine, reviewed data showing that high-protein, low-carbohydrate diets promote coronary artery disease independent of their effects on traditional risk factors such as blood pressure and cholesterol levels. The arterial damage was caused by animal-protein induced elevations in free fatty acids and insulin levels and decreased production of endothelial progenitor cells (which help keep arteries clean). The Atkins diet caused the most coronary artery blockages whereas a diet low in fat and high in unrefined carbohydrates caused the least amount of blockages.

Although this was shown in animals, it is likely true in humans as well. I'm not aware of a single study showing that a diet high in red meat can reverse the progression of coronary heart disease. All evidence is to the contrary.

The March 2014 study that Ornish cites as finding “a 75 percent increase in premature deaths from all causes and a 400 percent increase in deaths from cancer and type 2 diabetes among heavy consumers of animal protein under the age of 65,” also did not distinguish between types of animal protein. And it is worth noting that among people in the study over 65, heavy consumption of animal protein actually protected against cancer and mortality. (Also: the heavy protein consumers in the study were consuming nearly 30 percent more protein than the average American does.) “Whole foods—such as whole grain products and fruits and veggies—are healthy, but I think that dairy products, fish and lean cuts of meat or poultry can also be part of a healthy diet,” Steffen says.

The March 2014 study in Cell Metabolism did distinguish between animal protein and plant-based proteins. The abstract clearly states, “Respondents aged 50–65 reporting high protein intake had a 75 percent increase in overall mortality and a fourfold increase in cancer death risk during the following 18 years. These associations were either abolished or attenuated if the proteins were plant derived.”

The authors also reported that among those without type 2 diabetes at baseline, those in the high animal protein group had a 73-fold increased risk of developing diabetes during the study. The authors wrote:

“Notably, our results showed that the amount of proteins derived from animal sources accounted for a significant proportion of the association between overall protein intake and all-cause and cancer mortality. These results are in agreement with recent findings on the association between red meat consumption and death from all-cause and cancer (Fung et al, 2010; Pan et al, 2012). Previous studies in the U.S. have found that a low-carbohydrate diet is associated with an increase in overall mortality and showed that when such a diet is from animal-based products, the risk of overall as well as cancer mortality is increased even further (Fung et al, 2010; Lagiou et al, 2007). Our study indicates that high levels of animal proteins, promoting increases in IGF-1 and possibly insulin, is one of the major promoters of mortality for people age 50–65 in the 18 years following the survey assessing protein intake.”

The beneficial effects of lower protein intake were not seen in those over 65. In people over 65 the authors observed that older people may benefit from more protein because they tend to be malnourished (living alone, poorer GI absorption, etcetera). They wrote:

“The switch from the protective to the detrimental effect of the low-protein diet coincides with a time at which weight begins to decline. Based on previous longitudinal studies, weight tends to increase up until age 50–60 at which point it becomes stable before beginning to decline steadily by an average of 0.5 percent per year for those over age 65 (Villareal et al, 2005; Wallace et al, 1995). We speculate that frail subjects who have lost a significant percentage of their body weight and have a low BMI may be more susceptible to protein malnourishment.”

In any event, I wasn’t “wrong” about this; in my op–ed I was clear that these benefits were seen in those under age 65.

So there’s little evidence to suggest that we need to avoid protein and fat. But what about the claims Ornish makes about the success of his own diet—do they hold up to scrutiny? Not exactly. His famous 1990 Lifestyle Heart trial involved a total of 48 patients with heart disease. Twenty-eight were assigned to his low-fat, plant-based diet and 20 were given usual cardiac care. After one year those following his diet were more likely to see a regression in their atherosclerosis.

But here’s the thing: The patients who followed his diet also quit smoking, started exercising and attended stress management training. The people in the control group were told to do none of these things. It’s hardly surprising that quitting smoking, exercising, reducing stress and dieting—when done together—improves heart health. But fact that the participants were making all of these lifestyle changes means that we cannot make any inferences about the effect of the diet alone.

So when Ornish wrote in his op–ed that “for reversing disease, a whole-foods, plant-based diet seems to be necessary,” he is incorrect. It’s possible that quitting smoking, exercising and stress management, without the dieting, would have had the same effect—but we don’t know; it’s also possible that his diet alone would not reverse heart disease symptoms. Again, we don’t know because his studies have not been designed in a way that can tell us anything about the effect of his diet alone. There’s also another issue to consider: Although Ornish emphasizes that his diet is low in fat and animal protein, it also eliminates refined carbohydrates. If his diet works—and again, we don’t know for sure that it does—is that because it reduces protein or fat or refined carbohydrates?

Only one person in the experimental group of the Lifestyle Heart Trial was smoking at baseline, so it’s unlikely that made a significant difference. And I’m not aware of any studies showing that walking and stress management techniques alone can reverse heart disease.

We also published an analysis showing that improvements in dietary fat intake, exercise and stress management were individually, additively and interactively related to coronary risk.

Judging the quality of a study by the number of patients is like judging the quality of a book by the number of pages. There are so many other factors. Here's a blog in which I addressed this issue:

“Although the sample sizes of these studies were small, there were statistically significant differences in all of the above measures. It is a common belief that the larger the number of patients, the more valid a study is. However, the number of patients is only one of many factors that determine the quality of a study.



In our studies we ask smaller groups of people to make much bigger changes in lifestyle and provide them enough support to enable them to do so. And because the degree of these lifestyle changes is much higher than a control group is likely to make on their own, and the intervention is potent, it becomes easier to show statistically significant differences even though the number of patients is smaller.”

As Attilio Maseri, MD, an internationally known and respected cardiologist, wrote:

"Very large trials with broad inclusion criteria raise grounds for concern for practicing physicians and for the economics of health care. The first is the fact that the larger the number of patients that have to be included in a trial in order to prove a statistically significant benefit, the greater the uncertainty about the reason why the beneficial effects of the treatment cannot be detected in a smaller trial."

My colleagues and I conducted a demonstration project of 333 patients from four academic medical centers and four community hospitals. These patients were eligible for revascularization and chose to make these comprehensive lifestyle changes instead. We found that almost 80 percent were able to avoid surgery by making these comprehensive lifestyle changes.

It’s not just 48 patients. As I mentioned above, we found significant improvements in virtually all risk factors in almost 3,000 patients who went through my lifestyle program in 24 hospitals and clinics in West Virginia, Nebraska, and Pennsylvania.

Also, as I wrote in my op–ed in The New York Times, my colleagues and I have conducted randomized controlled trials that these same diet and lifestyle changes reverse the progression of other common chronic diseases. What happens to changes in blood pressure, cholesterol and weight are important only to the extent that they affect the underlying disease process (for example, degree of atherosclerosis, blood flow to the heart, cardiac events, changes in prostate cancer), which is what we documented. As I wrote:

The point here is not that Ornish’s diet—a low-fat, whole food, plant-based approach—is necessarily bad. It’s almost certainly healthier than the highly processed, refined-carbohydrate-rich diet most Americans consume today. But Ornish’s arguments against protein and fat are weak, simplistic and, in a way, irrelevant. A food or nutrient can be healthy without requiring that all other foods or nutrients be unhealthy. And categorizing entire nutrient groups as “good” or “bad” is facile. “It’s hard to move the science forward when there are so many stakeholders who say ‘this is the right diet and no other one could possibly be right,’” Bazzano says. Plus, discouraging the intake of entire macronutrient groups can backfire. When people dutifully cut down on fat in the 1980s and 1990s, they replaced much of it with high-sugar and high-calorie processed foods (think: Snackwell’s). If we start fearing protein, too, what will we fill our plates with instead? History tells us it’s not going to be spinach.

I agree that replacing fat with sugar is not healthful, as I’ve written about for decades. But replacing animal protein with well-balanced plant proteins is beneficial, and this is in the mainstream of what most scientists who do nutrition research believe.

For example, the then–American Dietetic Association published a position paper on plant-based diets in which they wrote, “It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate and may provide health benefits in the prevention and treatment of certain diseases.”

What is missing in Moyer’s article is the clinical experience that comes from helping people change their diet and lifestyle. I feel passionately about doing this work because it helps transform people’s lives for the better. These are not theoretical discussions; they are real people who have shown substantial improvements in their health and well-being—not just in risk factors but also in the underlying disease process. Over and over, I’ve seen patients with coronary heart disease so severe that they can’t walk across the street or work or play with their kids or make love or do much of anything without getting severe chest pain become pain-free after only a few weeks of making these diet and lifestyle changes. You can hear some of their stories here. We documented significant improvements in the heart’s function after only 24 days compared with a randomized control group.

And although no one likes to be falsely accused that almost everything they say is wrong, the bigger concern I have is that people who otherwise might have been motivated to make these highly beneficial diet and lifestyle changes may be discouraged from doing so by reading this essay by Ms. Moyer in which, unfortunately, almost everything she writes about my work is wrong.

Dean Ornish, MD

Founder and president, Preventive Medicine Research Institute

Clinical professor of medicine, University of California, San Francisco

Telephone: (415) 332-2525 x222

Melinda Wenner Moyer Responds

In his lengthy reply to my article Dean Ornish says I distort his beliefs, cite questionable studies and don’t have the clinical experience to assess nutritional evidence. If ones looks at the right data, he says, it’s clear that our country’s metabolic ills can be blamed on our increasing consumption of red meat and “bad” fats—both of which, he says, are proved to be unhealthy.

Ornish first takes issue with the data I cite on food consumption patterns from the National Health and Nutrition Examination Survey (NHANES). All consumption estimates are imperfect, of course, including the U.S. Department of Agriculture (USDA) data he cites. But looking more closely at the report (pdf) he discusses—as others already have—one finds that it, too, shows that in the decades from 1970 to 2000, when obesity and chronic disease rates skyrocketed, U.S. consumption of red meat and eggs dropped 12 percent. USDA data also show (pdf) that between 1970 and 2005 U.S. consumption of saturated fat–rich butter and lard as well as hydrogenated shortening decreased 17 percent. Indeed, the USDA explicitly states that most of our increase in consumption of added fats has been due to the growing use of vegetable oils and related products. So even when we look at the data Ornish likes, we still don’t see reason to blame America’s ill health on unprocessed red meat and saturated fats.

Ornish then cites a barrage of individual studies to back his claim that red meat and saturated fats are dangerous, including one that has not even been published in the peer-reviewed literature. He says that dietary meta-analyses and systematic reviews involving humans—such as the one I cited from 2010 that found no association between red meat consumption and heart disease or diabetes—can be misleading because the “noise obscures the ability to detect statistically significant differences.” Meta-analyses and systematic reviews have their limitations, of course, and they must be conducted carefully. But they don’t mask the truth; compared with individual studies, they get closer to it. As for Ornish’s contention that “the risk of premature death from all causes is higher in those eating red meat than those who do not,” I disagree, because the 2014 meta-analysis of 13 studies that I discussed did not find this to be true. (This lack of association is notable because this analysis probably overestimates risks associated with red meat consumption; all but two of the studies it assessed lumped processed meats into the “red meat” category.) Another meta-analysis of 21 studies found no association between saturated fat intake and heart disease. Again, meta-analyses of observational studies are certainly not perfect, but because they analyze all relevant data, they circumvent the problem of cherry-picking.

Ornish also dismisses the randomized controlled trials I cited in large part because the subjects in these trials did not adhere to the diets and reduce their fat intake enough. This argument raises two interesting points: First, it contradicts Ornish’s claim that he’s not really against fat, just certain types of fat. The fact is, individuals on his diet are supposed to consume (pdf) no more than 10 percent of calories from fat, and that’s very, very low compared to the average American’s adult’s intake of 33 percent of calories from fat. (An adult who consumes two tablespoons of olive oil in, say, a portion of salad dressing has already exceeded getting 10 percent of his day’s calories from fat if he’s eating 2,000 calories daily.)

Second, if subjects in dietary clinical trials—who are attending dietician-led classes and being monitored regularly—are unable to reduce their fat intake to anywhere close to Ornish’s recommendations, then how could his approach possibly be a sustainable solution for the entire country?

Ornish’s diet would probably be an improvement on the current American diet—if people could actually follow it long-term. But his claims about the dangers of saturated fat and red meat go beyond the science and in some cases contradict it. And although Ornish is right that I lack clinical experience, when analyzing evidence, distance can be useful. I have no horse in this race.