This month’s newsletter was curated and edited by: Dr. J.W. Holloway and his Team

For most of history, eating red meat has only been controversial only for a few religions of the world that hold the cow in reverence. Now, however, in many places of the world, eating red meat has become controversial in terms of its influence on health, specifically heart disease and cancer. This review will address the question of the relationship of eating red meat on heart disease. This review will present both sides of the argument presenting a review of research indicating the pros and cons of its effect on heart disease.

First, the review will consider the body of research indicating the deleterious effect on heart disease and then present the research indicating its positive effects.

Analysis

Contribution to Heart Disease

Pan et al. (2012) in a review article concluded that “substantial evidence” from epidemiological studies shows that consumption of meat, particularly red meat, is associated with increased risks of cardiovascular disease (meta-analysis by Micha, Wallace and Mozaffarian, 2010; updated by Micha, Michas, and  Mozaffarian, 2012) with the bottom line being “an elevated risk of mortality associated with red meat intake” (Sinha et al., 2009). They add the criticism that “most of these studies have been performed in populations with a particularly high proportion of vegetarians and did not differentiate between processed and unprocessed red meat (Fraser, 1999 and Sinha et al., 2009)

Pan et al. (2012), in a large study, 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 and cancer at baseline. Diet was assessed by validated food frequency questionnaires and updated every 4 years. They concluded that “greater consumption of unprocessed and processed red meats is associated with higher mortality risk. Compared with red meat, other dietary components, such as fish, poultry, nuts, legumes, low-fat dairy products, and whole grains, were associated with lower risk.” Pan et al. (2012) concluded that the replacement of red meat with alternative healthy dietary components may lower the mortality risk.

Pan et al. (2012) and Michaud et al. (2001) presented enough detail of their samples to illustrate the problem with an epidemiological, cohort, and au prior population research (in which dietary treatments are not imposed but consumption is determined through a questionnaire). As exemplified in these two studies, epidemiological studies are subject to the following criticisms:

• • The authors related health outcomes to only one variable among many variables that were correlated.
  • The trends in health observed were actually related to broad trends in lifestyle (meat eaters were generally less fastidious than those who ate less meat) of which only meat consumption was singled out as the culprit for health issues.
  • Even if the confounding effects could be removed through the use of covariables in statistical analyses for the correlated variables measured, meat consumption may be correlated with other lifestyle traits not measured [e.g., Pan et al. (2012) did not measure some traits that Michaud et al. (2001) found to be related to the carnivore lifestyle].
  • Epidemiological studies can reveal relationships, but since no treatments are imposed, they cannot reveal cause and effect.
  • The Quintiles studied in epidemiological studies artificially create discontinuities in the data so that an analysis of variance cannot be performed on the discrete classifications formed. In actuality, all the variables reported in epidemiological studies are continuous in nature and the variables measured may relate to each other in complex and nonlinear ways. To ignore these complications is to simplify the problem and possibly distort the analysis to fit preconceived ideas.
  • Epidemiological studies also suffer from the potential of inference basis. Inferences that can be drawn are dependent upon the population sampled and the randomness of population selection. For example, Pan et al. (2012) only sampled health workers and nurses. So, only inferences can be made about these populations. No evidence was presented in these epidemiological studies that the samples were selected randomly. If the samples weren’t distributed in a normal fashion, the statistical methods were invalid.

Some later epidemiological studies have been conducted in a manner to provide representative samples and to separate lifestyle determinants that were confounded in earlier trials. These very large trials (17,611 men and women 18 years and older) from the United States National Health and Nutrition Examination Survey (NHANES; 1986–2010) representative of the United States population (Kappeler et al., 2013) and the European Prospective Investigation into Cancer and Nutrition (EPIC) which followed half a million people in 10 European countries for more than 12 years (Rohrmann et al., 2013) found no association between unprocessed red meat consumption and any cause of death, including cardiovascular disease. Micha et al. (2010} pooled data from 1.2 million people from 20 countries in a meta-analysis concluding that consuming 100 g/d of unprocessed red meat was not associated with coronary heart disease risk.

In recent years, the emphasis on the deleterious effects of diet on human health has obscured the fact that humans require a high-quality diet in order to develop and prosper. Higgs (2000) pointed out that over the 20^th and 21^st centuries, the quality of the world’s diet in terms of nutrient supply has improved. Thus, the stature and lifespan of humans now living surpass any previous generation on record. Meat is a concentrated nutrient source historically considered essential for optimal human physiological development (Higgs, 2000).

Despite the recent focus on some epidemiological data has led to inferences of a possible relationship between meat consumption and increased risk of certain forms of cancer and certain cardiovascular and metabolic diseases, meat consumption has long been considered to be of evolutionary importance to the human species, especially in terms of the development of the brain and intellectual development (Pereira and Vicente, 2013).

Contribution to Prevention of Heart Disease

Teicholz (2014) reviewed the human nutrition literature and catalogued the development of the science of human nutrition in the U.S. showing the systematic error that occurs in any scientific field when an attractive hypothesis that appears intuitively correct is promulgated by a charismatic scientist to the extent that it is accepted and then subsequent research is oriented to bolster the hypothesis and research funding agencies reward discovery of evidence supporting the “party line.”  The hypothesis are ostensibly reinforced by researchers whose main goal is to have successful careers. Therefore, they conduct research in a manner that not only assures that the hypothesis is proved, but that their careers are promulgated. Teicholz (2014) documents how the hypothesis becomes unassailable dogma. The hypothesis that she addresses is that “if you eat fat, you will become fat.”

The bottom line of Teicholz (2014) is that “a higher fat diet is almost assuredly healthier in every way than one low in fat and high in carbohydrates.” She says that the recent body of research indicates that the only way to consume an adequate amount of fat in order to stay healthy is to consume saturated fat associated with whole fat in dairy, eggs, and meat—even fatty meat (these foods are a necessary component of a healthy diet) (Teicholz, 2014).    

Teicholz (2014) documents that over the past decade, a preponderance of high-quality scientific studies has shown this to be the case to the extent that the evidence is overwhelming. This body of work has shown beyond doubt that a high-fat, low carbohydrate diet will “fight heart disease, obesity, and diabetes” performing better in this regard than “the Mediterranean diet” and the commonly accepted “healthy” low-fat diet promulgated in the West. The low-fat diet has developed a bad track record in all important dimensions as evidenced by the rapid escalation of obesity, diabetes, and heart disease since it was prescribed by the American Heart Association in 1961 and then adopted by the USDA in 1980 as the official dietary plan for all American men, women, and children.

The AHA prescription was based on the all appealing hypothesis of Dr. Ansel Keys of Cornell University that he and others “proved up” in epidemiological studies in which, as shown above, one cannot extricate a single factor from the jumble of interrelated and totally confounding effects on any variable of interest (in this case heart disease). The hypothesis went viral in the U.S. because it sounds right and its proponents were good salesmen. The initial “foothold” was gained by the fortuitous timing that the President of the United States after the end of World War II, Dwight Eisenhower, had a heart attack. His doctor completely accepted the hypothesis, providing the needed venue to popularize the notion by prescribing a rigorous diet to the President, who ultimately died of heart disease while on the diet. Dr. Keys, however, had gained the momentum necessary to set a path through his influence in the AHA and the U.S. National Institute of Health (NIH) to set the hypothesis in stone as the law of the land (Teicholz, 2014). 

Teicholz (2014) summarizes the course of events this way: “This original mistake by low-fat diet proponents has been compounded over the years in a number of ways; by billions of dollars spent to prove the hypothesis, by vested interests lining up behind it, and by research careers coming to depend on it. Biases developed and hardened. Researchers quoted inadequate studies back and forth to each other, confirming their biases, as if in a hall of mirrors. Critics were sidelined and silenced. Researchers conducting experiments that didn’t back the ‘party line’ faced the probability of not being successful in attaining grants from the most prestigious organizations (NIH, NSF, and AHA) as well as facing the probability of failing to get their work published in prestigious peer-reviewed journals, thereby wrecking their careers (failing to make tenure).”

“And eventually a universe of nutrition experts came to believe that meat, dairy, and eggs were dangerously unhealthy foods, forgetting that their ancestors had ever milked a cow. Initially, animal fats were condemned for raising blood cholesterol, then for raising low-density lipoproteins (LDL’s). Now, we know that both metrics are unreliable indicators of heart disease.” Now, according to Teicholz (2014), “the case against saturated fat has collapsed.”

But, finally, as reported by Teicholz (2014), over the last decade definitive clinical research trials have been reported that a low-fat diet does not fight obesity, heart disease, diabetes, or any kind of cancer. The low-fat diet tested in these clinical trials was the one promoted as being the ideal: plenty of fruits and vegetables, whole grains, and a limited amount of lean meats. This diet has been ingrained into the psyche of Americans to the degree that there may be no way to turn back. Teicholz (2014) sites definitive trials (not epidemiological trials) conducted since 2000 that reveal the problems with low-fat, low-meat diets (Johnson, 2012; Krauss, 2000; and Siri-Torino et al., 2010a, b).

The following problems were identified by these researchers in low-fat, low-meat diets:

• • Reduction of animal products in diets means that dietary fat is largely vegetable and olive oils. Olive oil has not been consumed widely in the past and has not been shown to benefit health. Vegetable oils, on the other hand, are highly unstable and, when heated to temperatures required for frying, create trans fats and oxidation products that have shown to be harmful to health.
  • Diets with low levels of animal products risk being deficient in many nutrients. Red meat, cheese, eggs, and whole milk are the richest source of nutrients required for growth, reproduction, and prevention of muscle and bone deterioration with aging
  • Reduction of animal products in the diet results in people getting their needed energy from carbohydrates (human bodies are programmed to get energy one way or the other). Obesity, heart disease, and diabetes have been shown to result from diets high in refined carbohydrates not from diets high in fat or meats.

Teicholz (2014) concluded that the research from controlled clinical trials conducted during this millennium bolster the history of man in that it is shown that beef (even fatty beef) has always and will continue to occupy the center of the plate because it is the most nutritious food in the world.

Binnie et al. (2014) indicated that the action demanded by current evidence is a paradigm shift in dietary consultation toward inclusion of unprocessed red meats in a healthy diet. They refer to an inconsistent history in reports of epidemiological trials concerning the relationship between consumption of red meats and health (Micha, Wallace, and Mozaffarian, 2010; Wyness et al., 2011; and Teicholz, 2014) and to recent research indicating differential effects on health from consumption of unprocessed red meats and processed meats as shown in large population studies both in Europe and North America. These more recent studies have shown no association between intakes of unprocessed red meat and any cause of death, including cardiovascular disease (Kappeler, Eichholzer, and Rohrmann, 2013; and Rohrmann et al., 2013). In the largest meta-analyses of worldwide evidence yet reported, Micha et al. (2010) reported no association between unprocessed red meat and cardiovascular disease.

These recent epidemiological trials differ from earlier studies in that they collected data targeted toward differentiating lifestyle components conducive to chronic disease (Binnie et al., 2014). The results of these population studies designed to distinguish causes of disease are supported by controlled experimentation that has found that, within the context of heart-healthy diets: 1) the effect of the consumption of lean red meats on LDL-cholesterol is no different than for white meats (Davidson et al., 1999; Maki et al., 2012; and Roussell et al., 2012), and 2) red meats have a relatively neutral fatty acid profile with respect to blood cholesterol levels (Wyness et al., 2011).

When these results are combined with recent research increasing the understanding of human requirements for key essential nutrients such as high-quality protein throughout the life-cycle and the fact that red meats are the richest sources of bioavailable essential nutrients, there is strong evidence for emphasizing the value of nutrient-rich foods such as red meats as part of a healthy diet (Elango, Ball, and  Pencharz, 2012; Elango et al., 2010; FAO, 2013; and Binnie et al., 2014). Binnie et al. (2014) indicate that the initial reason for recommendations to limit red meat intakes was to reduce saturated fat intakes. Large, recent meta-analysis studies have concluded that there is no clear evidence to support these dietary guidelines designed to decrease saturated fat intake (Chowdhury et al., 2014; Siri-Tarino et al., 2010).

There is now evidence indicating that these guidelines inadvertently contributed to dietary changes associated with the rapid rise in the prevalence of obesity since the 1970s as well as other risk factors conducive to heart disease (Danaei et al., 2009; and Slater et al., 2009). Satiety factors governing food intake dictate that a decline in caloric intake from nutrient-rich foods such as beef, milk, and eggs is compensated for by an increase in caloric intake from fats (including trans fats) and refined carbohydrates found in many processed convenience foods (Slater et al., 2009). This shift is a major contributor to the epidemic of obesity and chronic disease in first world countries.

Conclusion

The research into the relationship of eating red meat and heart disease indicates that there is a need for a paradigm shift in dietary guidance regarding nutrient-rich foods such as red meats (Binnie et al., 2014). Binnie et al. (2014) concluded that “in an era when people in developed nations are increasingly overfed, but undernourished, emphasizing the value of eating a healthy balance of nutrient-rich minimally processed foods, including lean red meats, is likely to better serve public health (than focusing on dietary restrictions of red meats)”.