Vegetarian Diets and Quality of Life: Cause or Effect?

Very few would argue that simply excluding flesh from the diet will guarantee optimal health and longevity. However, the CBS Atlanta recently featured a concerning article, Study: Vegetarians Less Healthy, Lower Quality Of Life Than Meat-Eaters, suggesting that diets that exclude flesh promotes poor health. This article which has gathered much attention describes the findings of a cross-sectional survey from Austria that was published in PLoS One.1 This study has previously been addressed by Don Matesz in an very informative post. However, due to very serious omissions made by the CBS Atlanta, I felt that it was necessary to also address this study.

Vegetarian Diets and Perceived Health: Cause or Effect? 

It cannot be emphasized enough how important it is to recognize that this study, based on the Austrian Health Interview Survey (AT-HIS) examined dietary patterns after the subjects had developed health problems. Many vegetarians are not born into vegetarianism, but adopt a vegetarian diet later in life. Therefore, it is important to address why the vegetarians in this study adopted a flesh free diet. This important limitation was acknowledged by the Austrian researchers, who asserted:

Potential limitations of our results are due to the fact that the survey was based on cross-sectional data. Therefore, no statements can be made whether the poorer health in vegetarians in our study is caused by their dietary habit or if they consume this form of diet due to their poorer health status. We cannot state whether a causal relationship exists, but describe ascertained associations.

More importantly, in regards to causation the researchers asserted:

Our results have shown that vegetarians report chronic conditions and poorer subjective health more frequently. This might indicate that the vegetarians in our study consume this form of diet as a consequence of their disorders, since a vegetarian diet is often recommended as a method to manage weight and health.

The researchers suggested that if anything, it was not a flesh free diet that caused a higher rate of a number of health problems, but rather that it was poor health that caused these subjects to adopt a flesh free diet. This is similar to the phenomenon where former smokers report poorer perceived health than current smokers, because they quit smoking with the intention of alleviating poor health.2 This phenomenon is often referred to as reverse causality. 

Unfortunately, Benjamin Fearnow, the author of the article in the CBS Atlanta ignored the evidence suggesting that these results were the result of reverse causality, and instead suggested that a flesh free diet was actually the cause of a number of health problems:

...the vegetarian diet — characterized by a low consumption of saturated fats and cholesterol that includes increased intake of fruits, vegetables and whole-grain products — carries elevated risks of cancer, allergies and mental health disorders.

It is important to note that the Austrian Health Interview Survey did not measure food intake in actual detail. Subjects who reported consuming a flesh free diet were simply assumed to be consuming a diet poor in dietary cholesterol and saturated fat. However, in this study 36% of the vegetarian subjects were classified as lacto-ovo vegetarians, and 55% pescetarians (allowing fish, dairy and eggs). Only 9% were classified as vegans.1 Therefore, up to 91% of the subjects classified as vegetarians consumed dairy and eggs, being the richest sources of saturated animal fat and cholesterol, respectively. The CBS Atlanta failed to mention even the definition of a vegetarian diet used in this study, yet alone the breakdown of subjects in each category of vegetarian diet.

Vegetarian Diets and Cancer

At the time of the report, it was observed that 4.8% of the subjects of the Austrian Health Interview Survey classified as vegetarians had cancer, as opposed to 1.8% of the subjects following an omnivorous diet rich in meat. Unfortunately, no details were provided as to what portion of the studied population adopted a flesh free diet after diagnosis. However, data from previous studies suggest that cancer patients are highly motivated to adopt a plant based diet. As described previously: 

The results of a recent study from the Netherlands illustrates the critical importance of considering reverse causality in research on plant-based diets. The researchers found that 75% of the vegetarian participants with cancer adopted a vegetarian diet after diagnosis, consistent with previous research which found that cancer survivors are highly motivated to adopt a more plant-based diet with the intention of improving poor health.3 4

If the 75% figure from the study from the Netherlands is to be considered representative of this Austrian population, this would suggest that only 1.2% of the vegetarians adopted a flesh free diet prior to diagnosis of cancer. This is lower than the 1.8% figure for omnivores following a meat rich diet, but similar to that of the omnivores following a diet low in meat. Unfortunately, due to the lack of reliable data these estimates should be taken with a grain of salt. 

Prospective (forward-looking) studies which measure diet before diseases are diagnosed are much less likely to be complicated by reverse causality than cross-sectional studies, and therefore considered to be more appropriate for determining causality. I previously carried out a meta-analysis of 5 prospective cohort studies comparing the rates of cancer incidence in vegetarians compared to health conscious omnivores. For this review, I updated the meta-analysis to include the rates of major cancers in the Adventist Mortality and Adventist Health studies. In addition, I limited the inclusion criteria to studies that provided estimates specifically for subjects classified as either vegans, or lacto-ovo vegetarians.

In a meta-analysis including 7 prospective cohort studies, vegetarians had a statistically significant 9% lower risk of cancer incidence compared to health conscious omnivores (Fig. 1).5 6 7 8 9 It is important to note that meat intake was relatively low in the omnivorous group in these studies, especially taking into account that a significant portion of the omnivorous subjects were actually classified as semi-vegetarians. This suggests the difference in cancer incidence may be greater when compared to regular meat eaters.

FIGURE 1. Risk ratios and 95% CIs for fully adjusted random-effects models examining associations between vegetarian diets in relation to cancer incidence. ¹Mortality from cancers of the breast, colorectal, lung, prostate and stomach combined. VEG, vegetarian diet.

The finding of a decreased risk of cancer in vegetarians may be explained, in part, by a diet devoid in heme iron. Controlled feeding trials have established that NOCs (N-nitroso compounds) arising from heme iron in meat forms potentially cancerous DNA adducts in the human digestive tract, likely in part, explaining the significant association between heme iron and an increased risk of colorectal cancer in recent meta-analyses of prospective cohort studies.10 11 12 Heme iron has also been associated with numerous other cancers.

Vegetarian Diets and Heart Disease

In the Austrian Health Interview Survey, it was suggested that subjects classified as vegetarians were more likely to have had a history of heart attacks. It is important to note however, that, plant-based diets, poor in saturated fat and cholesterol have for long been adopted by individuals at risk of coronary heart disease. For example, it is known that in studies carried out as far back as the late 1950s, subjects with unfavorable blood cholesterol levels tended to limit intake of dietary cholesterol and saturated fat in order to improve cardiovascular risk factor.13

I previously carried out a meta-analysis of 7 prospective cohort studies comparing the rate of death of coronary heart disease of vegetarians compared to health conscious omnivores. For this review, I examined the incidence of coronary heart disease, and limited the inclusion criteria to studies that provided estimates specifically for subjects classified as either vegans, or lacto-ovo vegetarians. In a meta-analysis including 7 prospective cohort studies, vegetarians had a statistically highly significant 24% lower risk of coronary heart disease compared to health conscious omnivores (Fig. 2).5 6 7 14 15  

FIGURE 2. Risk ratios and 95% CIs for fully adjusted random-effects models examining associations between vegetarian diets in relation to coronary heart disease incidence. VEG, vegetarian diet.

The degree of reduction in risk of mortality from coronary heart disease observed in vegetarians in these cohort studies was generally in proportion to the expected reduced risk based on the differences in levels of total and non-HDL cholesterol, and blood pressure. This is supported by evidence from prospective cohort studies which found that diets characterized as being low in saturated fat and rich in dietary fiber decrease the risk of death from coronary heart disease. These findings are also supported by a recent meta-analysis of clinical trials and observational studies that found that vegetarian diets are associated with lower blood pressure and a lower risk of hypertension.16 Interestingly, the rates of hypertension tended to be lower in the vegetarians in the Austrian Health Interview Survey, suggesting that if the subjects adopted a vegetarian diet as a means to control hypertension, they were likely successful doing so.  

Vegetarian Diets and Mental Heath

In the Austrian Health Interview Survey, it was observed that subjects classified as vegetarians had a higher rate mental illnesses, defined as anxiety disorder or depression. Unfortunately, no data was provided as to what portion of the subjects adopted a vegetarian diet after developing these conditions. These findings have appealed to proponents of Paleoloithic diets who hypothesize that humans have a dietary requirement for meat in order to maintain large brains and mental health. However, in Powered By Plants: Natural Selection & Human Nutrition, Don Matesz examines an extensive body of research that casts considerable doubt on the hypothesis that meat is required to maintain mental health and is responsible for the evolution of the large human brain.

The findings from a number of clinical trials cast doubt on the hypothesis that an appropriately designed flesh free diet has adverse effects on, and that flesh rich diets, poor in carbohydrate have beneficial effects on overall mental health.

• Sacks and colleagues carried out a crossover trial to examine the effects of adding 250 g/day of beef isocalorically to the diet on blood cholesterol of vegetarians. As expected, during the meat phase total cholesterol and systolic blood pressure increased significantly. However, it was also observed that the participants experienced increased anger, anxiety, confusion, depression, and fatigue and less vigor compared to the vegetarian phase.17
• Beezhold and Johnston compared the mood scores of participants assigned to either a vegetarian diet, excluding all animal foods except dairy to participants assigned to either a omnivorous diet, or a diet that included fish, but excluded meat and poultry. The researchers found that the vegetarian group demonstrated significantly improved mood scores compared to both the omnivorous and fish groups.18
• Schweiger and colleagues compared the effects of a vegetarian diet and an omnivorous diet on global mood scores. They found that the vegetarian group demonstrated significantly better global mood, and that carbohydrate intake associated with better global mood.19
• Kieldsen-Kragh examined the effects of a vegetarian diet on rheumatoid arthritis. The researchers hypothesized that the participants may find the vegetarian diet too restrictive, and that therefore adherence to the diet would impose psychological distress on the them. However, contrary to their expectations, the vegetarian group demonstrated significantly improved physiological health, and were less anxious and depressed compared to the omnivorous group.20
• Brinkworth and colleagues examined the effects of a very low-carbohydrate diet and a low-fat diet on body weight and mood and cognitive function. Although there was no statistical difference in terms of weight loss between the groups, the participants assigned to the low-fat group demonstrated significantly improved mood scores compared to the participants assigned to the low-carbohydrate diet.21
• Holloway and colleagues carried out a crossover trial to examine the effects of a high-fat, low-carbohydrate diet on alterations to heart and brain function. The researchers found that the participants not only demonstrated significantly impaired cardiac health, but also impaired attention, memory recall speed, and mood while following the high-fat, low-carbohydrate diet.22
• Halyburton and colleagues examined the effects of a low and high-carbohydrate diet on mood and cognitive function. Although, unlike other studies, the researchers found that mood was similar in both groups, participants assigned to the low-fat diet demonstrated improved speed of processing compared to the participants assigned to the low-carbohydrate group.23

Mass Media as a Source of Health Information

The article featured in the CBS Atlanta is just one example of many studies that are misinterpreted, likely intentionally by the mass media. Unfortunately, the mass media is certainly not a reliable source for health information, as their primarily concern is to publish news that appeal to their targeted audience. In this case it was meat eaters who desired to hear negative things about vegetarian diets. This is likely why many important studies do not receive appropriate media attention,  and why consumers are either left in the dark or simply confused about health information.

Although there is convincing evidence of the health benefits of an appropriately planned diet that either excludes or significantly limits the intake of flesh, such findings cannot be extrapolated to all diets that exclude flesh. The definition of a vegetarian diet only provides information as to what foods an individual restricts, and not which foods are included. This is why the emphasis of a healthy diet also needs be on which foods are included, not only on those that are excluded. Future research in this area should address what foods vegetarians are substituting meat with,  the length of adherence to a vegetarian diet, and whether subjects adopted a vegetarian diet in order to alleviate poor health. This would allow for a considerably more meaningful interpretation of the effects of vegetarian diets.

Grass-Fed Animal Foods and Diseases of Civilization: Cardiovascular Disease in Ancient Civilizations

Vilhjalmur Stefansson was an Artic explorer known for his observations on the traditional living Inuit-Eskimo, which he lived together with in the winter of 1906-1907 in the Mackenzie Delta of Canada. Stefansson asserted that during this time he subsisted on traditional Inuit fare, based almost exclusively on flesh. In part based on less than extensive observations of the health of the Inuit, Stefansson hypothesized that a number of chronic and degenerative diseases, including cancer are diseases of civilization which can be prevented by adherence to a pre-modern diet and lifestyle. However, Stefansson did not suggest that only flesh based dietary patterns, such as that consumed by the traditional living Inuit, but also primarily vegetarian diets, such as that consumed by the Hunza may protect against such diseases.1 

The term diseases of civilization, which Stefansson has contributed to the popularization of is frequently referred to by proponents of Low-Carb, Paleo, Primal and Weston A. Price Foundation type diets. Many of these proponents have extrapolated limited suggestive evidence that obesity, type 2 diabetes, coronary heart disease, certain cancers, and a number of other chronic and degenerative diseases were uncommon during the Paleolithic period to suggesting that foods derived from naturally raised, grass-fed animals, as was consumed by Paleolithic humans must therefore somehow provide protection against these so-called diseases of civilization. Many of these proponents have also claimed that a vast number of scientific studies that have been used as evidence to conclude that animal foods increase the risk of such diseases have been complicated by confounding of other unhealthy foods and lifestyle factors, or by the use of unnaturally raised animal foods. This series of posts will examine the evidence to help determine whether these claimed confounding variables can actually explain the evidence linking animal foods with certain chronic and degenerative diseases, often referred to as diseases of civilization, but also as western diseases, lifestyle diseases and diseases of affluence.

In 1928, Stefansson and his colleague Karsten Anderson participated in a monitored experiment partly funded by the meat industry in which they consumed a flesh exclusive diet for the period of one year. Although the researchers concluded that these two men were in good health throughout the experiment, Anderson experienced a severe elevation in blood cholesterol, with measurements as high as 800 mg/dl on one occasion, which returned to pre-experiment levels after resuming a higher carbohydrate diet.2 A glucose tolerance test carried out immediately after the termination of the meat based experiment showed a marked rise in blood sugar in both men compared to a subsequent test carried out after resuming a higher carbohydrate diet. Glucose was detected in the urine of Anderson in the test following the meat based experiment, a marker of untreated diabetes. This abnormality was not detected in the subsequent test after resuming a higher carbohydrate diet.3

Short-term experiments such as this cannot provide adequate insight into the long-term consequences of following such a diet, as it can take many decades for diseases caused by exposure to harmful substances to become clinically significant. For example, the greatest risk of excess death from radiation-related solid cancers among the atomic bomb survivors of Hiroshima and Nagasaki was more than half a century after exposure.4 Furthermore, other flesh based experiments have resulted in considerably more unfavorable outcomes. For example, in 1906, Russell noted an even earlier experiment: 

A recent instance occurred in South Africa, where about twenty natives out of some hundreds who were supplied with a large amount of flesh, as an experiment, by mine-owners, died, and many others were ill.5

Cardiovascular Disease in Ancient Civilizations

The traditional living Inuit's were certainly
not immune from atherosclerosis

If a diet rich in naturally raised animal foods provides protection against cardiovascular disease as many proponents of Low-Carb type diets claim, it would be expected that traditional living populations consuming such a diet, particularly those living prior to the rapid westernization of the globe would demonstrate evidence of superior cardiovascular health compared to those populations who subsisted primarily on starchy staples, including grains, legumes and tubers. Populations who have inhabited the arctic, where scant plant matter is available throughout most parts of the year, such as the Inuit and Aleut were forced to subsist almost exclusively on hunted marine animals for extensive periods of time.1 6 This should make these populations suitable to study the hypothesis that naturally raised animal foods protect against cardiovascular disease.

Contrary to claims of the traditional living Inuit being immune from cardiovascular disease, evidence of severe atherosclerosis has been identified in several frozen mummies of Alaskan Inuit dating back to 400 CE and 1520 CE, both instances predating European contact.7 8 Atherosclerosis has also previously been identified in several artificially prepared mummies of Aleut-Unangan hunter gatherers who lived in the 18th century in the Aleutian Islands in Alaska.9 10 Recently the HORUS study, which examined an additional five recovered mummies of Unangan hunter gatherers who lived in the mid and late 19th century found definite evidence of atherosclerosis in several major arteries in all three who were over the age of 25.11

When considering the findings from all of these Alaskan Inuit and Aleut mummies it becomes evident that these Alaskan natives likely experienced a greater incidence of atherosclerosis, especially given the young mean age compared to the three other ancient populations studied in the HORUS study. Unlike the Alaskan natives, these other three populations, which were the ancient Egyptians, ancient Peruvians and Ancestral Puebloans practiced agriculture and consumed grains. 

In addition to evidence of atherosclerosis from native Alaskan mummies, reports from medical officers provide further evidence of unfavorable rates of cardiovascular disease among the Inuit before the rapid transition to the western diet. In 1940, based on decades of clinical practice and reviewing reports of medical officers dating all the way back 175 years ago, Bertelsen, who is considered the father of Greenland epidemiology stated in regards to the mortality patterns among the Greenland Inuit that: 

...arteriosclerosis and degeneration of the myocardium are quite common conditions among the Inuit, in particular considering the low mean age of the population.12

Bjerregaard and colleagues performed a literature review for studies addressing the incidence of atherosclerosis and cardiovascular disease among the Inuit of Alaska, Canada and Greenland spanning from the 1930s to more recent decades. The researchers found that the incidence of atherosclerosis was generally similar to that of other western populations that suffered from high rates of cardiovascular disease. Mortality from stroke was found to be even higher, and mortality from all cardiovascular diseases combined was found to be similar or even higher among the Inuit. The researchers also found that mortality from coronary heart disease among the Inuit was not significantly different after adjusting for ill-defined causes of cardiovascular death, suggesting that the substantial proportion of cardiovascular deaths being classified as ‘garbage codes’, particularly in Greenland may have hidden a significant portion of deaths from coronary heart disease. The researchers concluded: 

The mortality from all cardiovascular diseases combined is not lower among the Inuit than in white comparison populations. If the mortality from IHD [ischemic heart disease] is low, it seems not to be associated with a low prevalence of general atherosclerosis. A decreasing trend in mortality from IHD in Inuit populations undergoing rapid westernization supports the need for a critical rethinking of cardiovascular epidemiology among the Inuit and the role of a marine diet in this population.12

A similar phenomenon to the misclassification of deaths from coronary heart disease among the Inuit populations has also been observed in France, which may largely explain the so-called French Paradox. Data from the World Health Organization MONICA Project suggests that the official mortality statistics for France significantly underreport deaths from cardiovascular disease compared to other countries, with deaths from coronary heart disease being underestimated by 75%. Other reports suggest that this is likely explained by a much higher rate of French doctors classifying deaths as due to ‘other causes’ than in other countries.13 14

It has been observed that among the Alaskan Inuit a higher intake of saturated fat is associated with elevated blood pressure, insulin resistance, glucose intolerance and carotid atherosclerosis, suggesting that the traditional Inuit foods relatively rich in saturated fat were likely to have been detrimental to the cardiovascular health of the Inuit.15 16 17 It has also been observed that among Alaskan Inuit elevated LDL cholesterol is associated with a greater than fourfold increased risk of cardiovascular disease.18 Furthermore, rheumatic disorders that have been linked to cardiovascular disease, such as gout and rheumatoid arthritis have been found to be just as, or even more common among the Eskimo populations compared to that of the general North American population.19 20 Established risk factors, a number of which are likely adversely affected by the traditional Inuit diet can probably in part explain the evidence of severe atherosclerosis and unfavorable rates of cardiovascular disease observed among the traditional living Inuit and Aleut populations. 

In the HORUS study it was found that two of the four Ancestral Puebloan who lived in southwestern United States dating between 1500 BCE and 500 CE exhibited probable evidence of atherosclerosis, the two other both being under the age of 30. These Ancestral Puebloans were identified as being from a time when they were transitioning from hunter-gatherers to farmer-foragers, and were likely to have relied on hunted animal foods to supply at least a modest portion of their diet. An additional Ancestral Puebloan mummy aged 18-22 found from a later period after a greater transition towards agriculture did not exhibit any evidence of atherosclerosis.11

In the HORUS study the ancient Egyptian mummies exhibited the next greatest frequency of atherosclerosis, with 29 (38%) of the 76 of the mummies exhibiting at least probable evidence of atherosclerosis.11 In their book Protein Power, Michael and Mary Eades assert that the ‘diet of the average [ancient] Egyptian consisted primarily of carbohydrates’, which they suggest was ‘a veritable nutritionist’s nirvana… rich in all the foods believed to promote health and almost devoid of saturated fat and cholesterol'. These authors go on to suggesting that the carbohydrate rich diet of the ‘average Egyptian’ which they describe as being based on whole-grain wheat and barley supplemented by a variety of fruits, vegetables, legumes, nuts and some goats milk is responsible for the atherosclerosis and obesity exhibited by the ancient Egyptian mummies.21

The authors of Protein Power suggest that complex carbohydrates, such as wheat made the ancient Egyptians obese

There is much evidence that casts doubt on these authors description of the diets of the ancient Egyptian mummies. For example, Macko and colleagues have shown that isotope analyses of the amino-acid composition of hair from the ancient Egyptian mummies far more closely resemble that of modern westerners following an omnivorous diet than a vegetarian, and especially vegan diet.22 In addition, David and colleagues showed that evidence from hieroglyphic inscriptions on ancient Egyptian temples suggest that the elites of ancient Egyptian society, being those who were primarily mummified consumed a diet rich in flesh and saturated animal fat. These researchers addressed the confusion surrounding the diet and atherosclerosis of the ancient Egyptian mummies, asserting: 

It is important to point out that there was a marked difference between the mainly vegetarian diet most Egyptians ate and that of royalty and priests and their family members whose daily intake would have included these high levels of saturated fat. Mummification was practised by the elite groups in society, ensuring that their remains have survived to provide clear indications of atherosclerosis; by contrast, there is a lack of evidence that the condition existed among the less well-preserved remains of the [mainly vegetarian] lower classes.23

The findings of a lower incidence of atherosclerosis among the lower classes of ancient Egypt who subsisted primarily on a carbohydrate-rich vegetarian diet are consistent with observations in Egypt in the early 20th century. In 1934, Rosenthal asserted:

Of interest is the report of Ismail in Egypt, who has communicated that among his private patients, whose diet is similar to that of the Europeans, the incidence of atherosclerosis is high, while in his hospital practice, composed mainly of natives, who subsist largely on a carbohydrate diet, the incidence of atherosclerosis is low.24

It is clear that the authors of Protein Power have confused the diet of the elites of the ancient Egyptian society, who certainly cannot be considered as the 'average Egyptian' with the largely vegetarian diet of the of the lower classes who exhibit a lack of atherosclerosis, and which scant evidence suggests were obese. The findings from ancient Egyptian mummies do not support the claimed benefits of a low carbohydrate, high saturated fat diet promoted by these authors.

In the HORUS study, despite having the highest mean age, nearly 10 years older than that of the Unangan and Ancestral Puebloans mummies, the ancient Peruvians exhibited the lowest incidence of atherosclerosis, being evident in 13 (25%) of 51 of the mummies. Compared to these other studied ancient populations, the Peruvians likely relied more on staple plant foods, such as corn, beans and tubers, although did consume some domesticated and hunted animals.11

The researchers of the HORUS study suggested that exposure to smoke from fire used for cooking and25

heating may help explain some of the degree of atherosclerosis identified in these ancient populations. However, the description of the use of fire for cooking in ancient Egypt provided by these researchers would apply primarily to the lower classes of ancient Egypt which exhibit a lack of atherosclerosis, rather than the mummified elites that these researchers examined who would typically have had servants to cook for them.

Gout was known to be common among 

the Mongols of the Golden Horde

In regards to the traditional living Inuit and Aleut, it has been suggested that the extensive exposure to seal oil lamps may help explain the relatively severe degree of atherosclerosis in these populations.  These findings should however be considered in light of evidence of atherosclerosis in other populations which have high exposure to hazardous smoke but consume contrasting diets. For example, it has been observed that the Papua New Guinean highlanders have a smoking prevalence of greater than 70% for males and 20% for females while also being exposed to smoke for up to twelve hours a day due to the use of centrally placed open wood fires in their houses which lack both ventilation and chimneys. Despite such a high exposure to hazardous smoke it has been observed that the Papua New Guinean highlanders have among the lowest age-adjusted incidence of atherosclerosis of any studied population. However, unlike the Inuit, the Papua New Guinean highlanders traditionally consumed a plant based diet with carbohydrate supplying more than 90% of total energy intake, predominantly derived from sweet potatoes.26 27

Another population that have historically been documented to subsist almost exclusively on a diet derived from grass-fed, free-ranging animals are the largely nomadic Mongolians. John of Plano Carpini who visited the Mongols in the mid-13th century noted:

[The Mongols] have neither bread nor herbs nor vegetables nor anything else, nothing but meat… They drink mare’s milk in very great quantities if they have it; they also drink the milk of ewes, cows, goats and even camels.28

Smith reviewed the literature regarding the health of the Mongols from the 13th century and noted that a number of unfavorable cardiovascular risk factors, including obesity and gout were both common disorders. Smith went on to state:

Cardio-vascular problems, although not then subject to diagnosis, may be suspected as well.29

In 1925, Kuczynski reported on the nomadic pastoralists of the Kirghiz and Dzungarian Steppes in Central Asia and northern China that were of Mongolian descent. Similar to the observations of the diet of the nomadic Mongols of the 13th century, Kuczynski observed that these nomadic pastoralists subsisted almost exclusively on enormous quantities of meat and milk from grass-fed, free-ranging animals. Other authors have also come to the same conclusions regarding the composition of the diet of the nomadic pastoralists of the Central Asian Steppes. For example, Tayzhanov asserted:

…the people [of the steppe] lived exclusively on meat, fat and sour milk. Bread was added only later and even then some households did not adopt or consume this food.30

Similarly, Barfield asserted:

In good legendary style, the pure Central Asian nomads eat only meat, marrow, and milk products {preferably ferments}. They despise farmers, farming, and grain…31

These findings suggest that the diet of these nomadic pastoralists of the Central Asian Steppes was almost exclusively animal based, virtually devoid of grains, legumes and refined carbohydrates. This should make these populations also suitable to study the hypothesis that naturally raised animal foods protect against cardiovascular disease. However, not only did Kuczynski observe that these nomadic pastoralists suffered from high rates of obesity and gout similar to the Mongols of the 13th century, Kuczynski's observations further extended to the diagnosis of cardiovascular disease and other dietary related disorders. Kuczynski asserted:

They get arteriosclerosis in an intense degree and often at an early age as shown by cardiac symptoms, nervous disordes, typical changes of the peripheral vessels, nephrosclerosis and, finally, apoplectic attacks. Even in men thirty-two years old I frequently observed arcus senilis.32

It was also observed that in the 1960s the prevalence of coronary heart disease among the nomadic pastoralists in Xinjiang in northern China who consumed large quantities of animal fat from grass-fed, free-ranging animals was more than seven times higher than that of other populations both within Xinjiang and throughout China which consumed significantly less animal fat.33 These observations support the suggestion that cardiovascular disease was common among the Mongols of the 13th century who subsisted almost exclusively on a diet based on grass-fed, free-ranging animals.

Dispelling Grass-Fed Fairy Tales

These findings from populations living before the 20th century suggest that similar to the findings from people studied in more modern times, a greater intake of minimally refined plant foods strongly predicts a lower prevalence of atherosclerosis and cardiovascular disease. These findings cast doubt on the hypothesis that foods from organic, naturally raised animals protect against cardiovascular disease compared to staple plant foods. Furthermore, these findings suggest that the traditional living populations that relied predominantly on naturally raised animal based foods suffered from complications related to cardiovascular disease at a relatively young age and are poor role models for health.

Future posts in this series will further address how naturally raised animal foods influence cardiovascular disease, as well as other so-called diseases of civilization.


Please post any comments in the Discussion Thread.

Traditional Diets in Asia Pacific and Implications for Health, and the History of Disease Prevention

I previously reviewed the health of a number of primitive populations, including evidence from numerous preserved Inuit mummies that predate western contact, demonstrating that without consuming a morsel of modern processed food throughout their entire lifetimes, the traditional Inuit developed atherosclerosis, osteoporosis, breast cancer and numerous other chronic and degenerative diseases that are evidently partly explained by their carnivorous diet. The diets and incidence rates of disease in traditionally living populations can provide implications for disease prevention, which can be used to supplement the current knowledge of the impact of dietary and lifestyle factors on diseases from other forms of evidence, including observational, laboratory and clinical studies in order to achieve maximum protection.

The Nomadic Kirghiz and Dzungarian Plainsmen

In the 1920’s, Kuczynski reported on the nomadic plainsmen of the Kirghiz and Dzungarian Steppes in Central Asia and estimated that they consumed an astonishing 20 liters of fermented mare’s milk, and between 10 to 20 pounds (4.5 to 9kg) of meat per day.1 2 Lack of systematically documented dietary data however suggests that these findings could have been slightly overestimated, as evidently has been the case for early researcher's estimates of the Masai's intake of milk, meat, cholesterol and total energy.3 Nevertheless, these nomadic plainsmen consumed enormous quantities of organic pasture raised animals foods, perhaps among the largest ever documented. 

Kuczynski noted that these nomads, evidently largely as a result of their diet experienced a high incidence of obesity, premature extensive atherosclerosis, contracted kidney, apoplexy, arcus senilis, and gout.4 5 In specific, Kuczynski asserted that:2

They get arteriosclerosis in an intense degree and often at an early age as shown by cardiac symptoms, nervous disordes, typical changes of the peripheral vessels, nephrosclerosis and, finally, apoplectic attacks. Even in men thirty-two years old I frequently observed arcus senilis.

The Nomadic Kirghiz Plainsmen

Kuczynski compared the diet and health of these nomadic plainsmen with Russian peasants, who had an apparent low incidence of these conditions while consuming a vastly different diet. Their diet was based on soup, bread, pickles, potatoes, with very little meat, but consumed large amounts of alcohol.5 In comparison to the nomadic plainsmen, Kuczynski asserted in regards to these Russian peasants that:2

Repeatedly I found at the age of about seventy years no signs of arteriosclerosis, no arcus senilis, etc.; they were men of youthful appearance, with no grey in their still abundant growth of hair, and with their sexual functions still intact.

For more information regarding the health of nomadic populations, Don Matesz has previously posted an informative review addressing the high rates of obesity, cardiovascular disease and cancer among the modern, still largely nomadic Mongols consuming diets rich in organic pasture raised animal foods.

The Native Indonesians 

In 1916, Cornelis D. de Langen observed that the native Javanese, the indigenous people of the Indonesian island of Java who consumed a diet which was 'mainly vegetarian with rice as the staple, that is very poor in cholesterol and other lipids', had very low levels of serum cholesterol and incidence of coronary heart disease.6 Conversely, de Langen observed that their Javanese counterparts who worked as stewards on Dutch passenger ships and consumed traditional cholesterol laden Dutch food had much higher levels of serum cholesterol and incidence of coronary heart disease.7 Blackburn noted in regards to de Langen's classical findings from Indonesian hospitals that:6 

Pursuing this clinical impression, he reviewed 10 years of admissions charts and found only 5 cases of acute gallbladder disease among many thousands of patients passing through the medical wards and only 1 case on the surgery service among 70,000 admissions surveyed. 

Following these observations, de Langen stated in regards to the rarity of vascular disease among the Javanese that:6 

thrombosis and emboli, so serious in Europe, are most exceptional here. This is not only true of internal medicine, but also on surgery, where the surgeon needs take no thought of these dreaded possibilities among his native patients. Out of 160 major laparotomies and 5,578 deliveries in the wards, not a single case of thrombosis or embolism was seen.

These findings closely resemble observations from over 15,000 operations carried out in Norway during the period around World War II, where the changes in incidence of post-operative thrombosis was consistent with changes in the availability of cholesterol laden foods [reviewed previously]. Blackburn also noted in regards to de Langen’s 1922 experiment, which is regarded as apparently the first ever systematic feeding experiment of diet in relation to serum cholesterol levels, that:6

…he found an average 40 mg/dl increase in cholesterol in 5 Javanese natives who were shifted from a rice-based vegetarian cuisine to a 6-week regimen high in meat, butter, and egg fats.

These findings were reproduced decades later in hundreds of tightly controlled feeding experiments, firmly establishing that dietary cholesterol and isocaloric replacement of complex carbohydrates and unsaturated fat by saturated fat raises LDL and total cholesterol in humans.8

In 1908, Williams noted in regards to the findings of early doctors who practiced in Indonesia and the rarity of cancer among the Javanese that:9

...a single example of a malignant tumour in a native being esteemed a great rarity.

The Okinawans

In 1949, a government survey found that in Okinawa, known to have the highest concentration of centenarians in the world, the population consumed about 85% of their total energy intake from carbohydrates, with the staple at the time being the sweet potato. The dietary survey also showed that the Okinawans derived about 9% of their energy intake from protein and less than 4% of energy from all sources of animal foods combined (Table 1).10 These findings were largely consistent with previous dietary surveys dating back to 1879 and 1919.11

In 1946, Steiner examined autopsies of 150 Okinawans, of which 40 were between the age of 50 and 95. Steiner noted only seven cases of slight aortic atherosclerosis, all of which were found in those over the age of 66, and only one case of calcification in the coronary arteries. In 1946 Benjamin reported similar findings from a study of 200 autopsies on Okinawans.12

Even in 1995 the observed rates of coronary heart disease and dietary related cancers, including that of the colon, prostate, breast and ovarian in Okinawa were not only many fold lower than that of the United States, but even significantly lower than that of mainland Japan.10 This may be explained by the likelihood that these diseases are slowly progressive diseases and therefore the more traditional Okinawan diet consumed several decades prior would still have played a major role in the development and manifestation of these diseases.13 14 15

The Papua New Guineans

The Papua New Guineans traditionally subsisted on a plant based diet, of which a number of varieties of sweet potatoes typically supplied over 90% of dietary intake. They also grew a number of other crops including corn, as well as sugar cane which was consumed as a delicacy. Pig feasts are organised a few times a year, but at which pork is not consumed in excess of 50 grams. A dietary survey on the Papua New Guineans highlanders estimated that carbohydrate accounted for 94.6% of total energy intake, among the highest recorded in the world. Total energy intake was adequate, however only 3% of energy intake was derived from protein (25g for men and 20g for women), yet there was no evidence of dietary induced protein deficiency or anemia. Furthermore, this surveyed population was described as being muscular and mostly very lean, physically fit and in good nutritional state.16 17 They also drank 'soft' water which is considered a risk factor for cardiovascular disease. It was estimated that tobacco was smoked by 73% of males and 20% females. Also, the highlanders spend up to twelve hours a day inside a smoke-filled house due to centrally placed open wood fires with little ventilation and no chimneys in their homes, resulting in a very high exposure to hazardous smoke in this population.16 

Despite cardiac risk factors including high exposure to smoke and soft drinking water, a number of authors observed a great rarity of incidence of atherosclerosis, coronary heart disease and stroke among the traditional Papua New Guineans, but also noted an increase in incidence paralleling the Westernization of the nation. In 1958, Blackhouse reported on autopsies of 724 individuals between 1923 and 1934 and found no evidence of heart attack incidence and only one case of slight narrowing of the coronary arteries. However, it has been suggested that this study was selective as only a small portion of the autopsies were performed on females or the elderly. In 1969, Magarey et al. published a report on the autopsy results of 217 aortas and found a great rarity of atherosclerosis. The authors noted that the prevalence and severity of atherosclerosis was less than had been reported in any previously investigated population.18 In 1973, Sinnett and Whyte published findings from a survey of 779 highlanders using electrocardiograms among other methods, and found little probable evidence of coronary heart disease, and no clinical evidence of diabetes, gout, Parkinson’s disease, or any previous incidence of stroke.16

For a population that consumed virtually the highest intake of carbohydrates out of any population to also have virtually the lowest incidence of atherosclerosis and diabetes ever recorded highlights the vital importance of the health properties of specific carbohydrate rich foods. These findings further question certain 'carbohydrate-induced dyslipidemia' hypotheses, emphasized by certain researchers, who perhaps intentionally do not always take the quality of carbohydrate rich foods into careful consideration.19

In 1900, Sir William MacGregor reported in the Lancet in regards to the observed rarity of cancer among the native Papua New Guineans, asserting that:20

For nine and a half years I never saw a case in British New Guinea ; but at the end of that time there occurred an example of sarcoma of the tibia in a Papuan, who had for seven or eight years lived practically a European life, eating tinned Australian meat daily.

In 1974, Clezy brought to attention the rarity of mortality from colorectal cancer among the Papua New Guineans, for which the observed annual rate per 100,000 was 0.6 for men and 0.2 for women. These rates were 100 fold lower than that of many developed nations during the same time period, although this could have been in part explained by underdiagnosis.17

Even in more recent statistics after modest changes towards a western diet, the Papua New Guineans still had among the lowest rates of hip fractures in the world, which Frassetto et al. observed was more than 50 fold lower than that of the Scandinavian nations.21 Although these researchers ascribed the worldwide differences in rates of hip fractures to the ratio of vegetable to animal protein, evidence from prospective cohort studies and randomized controlled trials, as well as experimental animal models suggests that saturated fat may be at least as great, if not an even greater contributor to poor bone health.22 23 24 25 26

The Tokelauans and Pukupukans

In the video below, Plant Positive reviews the diet and health of the Tokelauans and Pupukans whose diet is rich in coconuts, as well as the diet and health of other South Pacific island populations.

The Tokelauns, and more on the Masai

A 1908 Review on the Causation of Cancer

In 1908, William Roger Williams published an extensive review of the medical literature and documentations from a large number of populations around the world before the widespread use of intensive farming practices. Williams observed that compared to the nations with carnivorous dietary patterns there was a significantly lower incidence of cancer among the nations subsisting predominantly on a plant-based diet. He also noted that groups within nations with carnivorous dietary patterns that largely abstained from animal foods, such as nuns, monks, slaves and prison inmates had a similar low incidence of cancer.9

Williams reported on the cancer rates of the area inhabited by the Gaucho of the Argentina Pampas, another nomadic population that subsisted predominantly on organic pasture raised animal foods, noting that:9

Cancer is commoner in Argentina which comprises the pampas region inhabited by the Gauchos, who for months subsist entirely on beef, and never touch salt than in other parts of South America. On the other hand, among the natives of Egypt, who are of vegetarian habits, and consume immense quantities of salt, cancer is almost unknown.

The Nomadic Argentinean Gaucho

These findings are largely consistent with modern reviews from prominent health authorities, including the report from the expert panel of the World Cancer Research Fund that produced convincing evidence that red meat is a major risk factor for cancer and that dietary fiber provides significant protection [reviewed previously]. However, these findings raise questions as to whether the Egyptians plant-based diet that is centered on wheat provides significant protection against salt sensitive cancers. In regards to the cancer incidence among the different ethnic groups of Egypt, Williams quoted from a 1902 publication in the British Medical Journal authored by Dr. F. C. Madden of Cairo that:9

The consensus of opinion among medical men in Egypt is, that cancer is never found either in male or female, among the black races of that country. These include the Berberines and the Sudanese, who are all Mussulmans, and live almost entirely upon vegetarian diet. Cancer is fairly common, however, among the Arabs and Copts, who live and eat somewhat after the manner of Europeans.

Williams also observed that the increases in incidence of cancer within populations coincided with increases in animal food intake. For example, in regards to the observed marked increase cancer incidence among the Native American’s after gaining easier means to hunt buffaloes, Williams asserted:9 

In this connexion it should be borne in mind, that in their primitive condition these savages had no horses and no firearms ; consequently it was no easy matter for them to kill the fleet buffaloes, on which they mainly depended for subsistence ; hence, in their primitive condition, they were generally less well nourished than when, after contact with whites, they had, by the acquirement of horses and firearms, become assured of a constant supply of their favourite food [coinciding with an increase in cancer incidence].

Historical Overview of the Reversal of Chronic Diseases 

In 1903, John Harvey Kellogg, the founder of the Kellogg Company asserted:

Dr John Bell, who was, about a hundred years ago [now two hundred years ago], professor in a leading college in London, wrote that a careful adherence to a vegetarian dietary tended to prevent cancer. He also stated that in some cases persons who had already acquired cancer had been cured by adherence to a non-flesh dietary. When I first read this book, I did not agree with the author; I thought he was mistaken; but I have gradually come to believe that what he says on this subject is true. 

These findings are consistent with Dr. Dean Ornish’s on-going Prostate Cancer Lifestyle Trial which has already produced strong suggestive evidence of reversal of prostate cancer growth.27 These findings are also consistent with experiments showing that dietary restriction of methionine, typically found in higher quantity and bioavailability in protein rich animal foods compared to unprocessed plant foods can inhibit and even reverse human tumor growth in animal models and in culture [reviewed previously]. 

Publications producing evidence of regression of atherosclerosis in humans dates back to the periods following both the World Wars in Scandinavia and the low countries of Europe, where a number of researchers found a trend between changes in intake of cholesterol laden foods throughout periods of food scarcity in the war and changes in the severity of atherosclerosis at autopsy [reviewed previously]. Several decades later during the 1960's and 70's experiments involving modest dietary and lifestyle changes or drugs produced the first angiographic evidence of modest regression of atherosclerosis.28

In experimental animal models, the first suggestive evidence of regression of atherosclerosis came from rabbit models produced by Anichkov and colleagues during the 1920’s. Beginning from 1957 much more substantial evidence of regression was produced in rabbits and then later replicated in a number of other species, including non-human primates.29 30

In 1970, Armstrong et al. published the first study producing substantial evidence of regression of atherosclerosis in non-human primates. Armstrong et al. induced severe autopsy proven atherosclerosis in Rhesus monkeys resembling that of human atherosclerosis by feeding a diet with 40% of energy from egg yolks for 17 months. The egg yolks were then removed from the diet of the remaining monkey’s and replaced by either linoleic acid rich chow or sugar rich low fat chow for three years reducing serum cholesterol to 140 mg/dl and resulting in a marked regression of atherosclerosis.28 31 These results were later reproduced in well over a dozen experiments in various primate species in which severe atherosclerosis was induced typically by feeding diets rich in dietary cholesterol and saturated fat and then reversed the process either by removing these atherogenic components, or by other means which significantly reduce serum cholesterol.30

During the late 1980’s, Dr. Dean Ornish and Dr. Caldwell Esselstyn began reversing atherosclerosis, and more importantly greatly decreased the number of reoccurring cardiac events in participants who adhered to a plant-based diet and often other lifestyle modifications.32 33 34 35 More recently Dr. Esselstyn has replicated his initial findings in around 200 participants over the period of a decade, with publication pending results showing a phenomenal success rate of a 99.5% reduction in reoccurring cardiovascular events [reviewed previously].

Caldwell Esselstyn on making heart attacks history

Please post any comments in the Discussion Thread. 

Debate with Dr. Colin Campbell in The Wall Street Journal

Dr. T. Colin Campbell

A recent article in The Wall Street Journal, titled Would We Be Healthier With a Vegan Diet?, featured Dr. Colin Campbell explaining the health benefits of a plant-based diet and the supporting science, with an opposing view given by Dr. Nanacy Rodriguez, a researcher who's profile shows an extensive list of grants from the livestock industry.1

Dr. Rodriguez’s opposing view raises considerable concerns as her statements are compromised by a number of serious methodological issues and relies largely on inaccurate stereotypes, stereotypes scripted and promoted by lobbying efforts of the livestock industry that promote fear of removing animal products from the diet.

Laboratory Experiments and the Promotion of Cancer

Dr. Nancy Rodriguez

Dr. Rodriguez questioned whether the cancer promoting effects of casein observed in Dr. Campbell’s laboratory can be extrapolated to other animal proteins, but provided scant evidence to the contrary. This resembles the misleading claims of the cholesterol sketpics, including Denise Minger that have been discussed in detail here.

It is well documented that dietary restriction of methionine significantly increases both the mean and maximum lifespan in the rodent model.2 3 Dietary restriction of methionine has also been shown to inhibit and even reverse human tumor growth in animal models and in culture demonstrating that tumors are methionine dependent, yet is relatively well tolerated by normal tissue.4

Compared to whole plant foods, both methionine content and bioavailability is significantly higher in most protein rich animal based foods, with little overlap.3 In addition plant foods contain thousands of phytonutrients which work together to protect against cancer. For example, studies have found that casein is still far more cancer promoting compared to soy protein even when both the diets were formulated to contain equivalent amounts methionine (Fig. 1). This was attributed largely to the difference in content of a number of protective phytonutrients.5

Figure 1. Total number (A) and total weight (B) of mammory tumors in rats, 25 weeks after N-nitrosomethylurea injection. Diet Groups: Casein, 20% casein; SPI, 19% soy protein isolate; SPI +Met., 19% soy protein isolate formulated to contain the equivalent amount of methionine as the casein group.

Due to the high content and bioavailability of methionine and lack of phytonutrients in other animal proteins, the observed cancer promoting effects of casein will therefore largely apply to other animal proteins. Furthermore, Dr. Rodriguez’s statement 'Casein is one of many proteins found in milk' made in an apparent attempt to disassociate milk protein from casein can be considered misleading when taking into account that casein makes up approximately 80% of the protein in bovine milk.6

Findings from Clinical Trials

The consensus that a number of dangerous substances including cigarette smoke promote cancer is purely based off epidemiologic, metabolic and laboratory studies. Therefore there is little justification for Dr. Rodriguez to claim as she did that a number of risk factors that have not been tested in clinical trials such as smoking play a significant role in the cause of cancer, but at the same time neglect evidence regarding replacing meat and dairy with whole plant foods and a decreased risk of cancer purely because of a lack of clinical trials.

A number of randomized controlled trials have actually demonstrated the damaging effects of animal protein in human cancers. For example, a randomized, placebo-controlled trial found that among men at high risk, those supplementing with milk protein were more than six times likely to develop prostate cancer compared to men supplementing with soy protein.7

A number of tightly controlled feeding trials with human participants have established that heme iron from the protein portion of meat increases the production of NOCs (N-nitroso compounds) in the digestive tract to concentrations similar to that found in cigarette smoke, of which most are cancerous.8 Furthermore, a controlled feeding trial found that NOCs arising from heme iron in meat forms DNA adducts in the human digestive tract, and DNA adducts are a well-established marker of cancer.9 These findings are consistent with recent meta-analyses of prospective studies that found that intake of both fresh red meat and heme from meat is associated with a significant increased risk of colorectal cancer.8 10

Based partly on these lines of evidence, in 2011 the expert panel from the World Cancer Research Fund reviewed over 1,000 publications on colorectal cancer and concluded that there is convincing evidence that both fresh and processed red meats are a cause of colorectal cancer.11 Furthermore, a more recent prospective study with over 2.24 million men and women found that compared to participants who consumed less than 1 serving per week, consuming 2 or more servings of meat significantly increased the risk of colorectal cancer.12

There is much controversy regarding the 'Dozens of randomized, controlled, clinical trials' that Dr. Roriguez’s appears to be referring to claiming that 'demonstrated that calcium and dairy products contribute to stronger bones'. For example the Harvard School of Public Health have asserted that:13

...the maximum-calcium-retention studies are short term and therefore have important limitations. To detect how the body adapts to different calcium intakes over a long period of time—and to get the big picture of overall bone strength—requires studies of longer duration.

Walter Willett, the Chair of the Department of Nutrition, Harvard is well known for criticizing the industries unfounded claims about the health properties of dairy. In regards to the 2010 USDA Dietary Guidelines he stated that:14

The guidelines continue to recommend three daily servings of dairy products, despite a lack of evidence that dairy intake protects against bone fractures and probable or possible links to prostate and ovarian cancers.

Willett nevertheless praised parts of the guidelines, stating that:

The guidelines appropriately emphasize eating more vegetables, beans, fruits, whole grains, and nuts and highlight healthful plant-based eating patterns, including vegetarian and vegan diets.

Dr. Rodriguez suggested that 'The Dietary Guidelines are founded on evidence-based, peer-reviewed scientific literature, and take into account the entire body of research, not just a single study', and that therefore her dietary recommendations are justified. However, evidence to the contrary was made clear in the report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010 that stated 'The DGAC did not evaluate the components of processed meats that are associated with increased risk of colorectal cancer and cardiovascular disease.'15 Thus the Dietary Guidelines did not sufficiently 'take into account the entire body of research', one of the reasons the guidelines have been scrutinized by the Harvard School of Public Health.13

Nutrient Density of Plant vs. Animal Foods

In regards to 'calorie efficiency', the most nutrient dense foods are dark green leafy vegetables which are leaps and bounds more nutrient dense than the phytonutrient and dietary deficient animal foods Dr. Rodriguez advocates, while also being dense in protein, calcium, iron and zinc.16 In fact, calcium from a number of dark green leafy vegetables is actually much more easily absorbed than that from bovine milk.17 In regards to protein intake, a meta-analysis of nitrogen balance studies found that the estimated requirements in healthy adults for the median and 97.5th percentile are 0.65 and 0.83 grams of protein per kg of body weight respectively,18 amounts easily obtained from plant-based dietary plans formulated by Dr. Campbell and his colleagues.19 Furthermore, there is little justification for Dr. Rodriguez as she has done to advocate dairy on the basis that it is artificially fortified with Vitamin D while at the same time downplaying the nutrient density of plant-based foods due to a lack of certain nutrients such as Vitamin B12 and Vitamin D that can be easily supplemented in plant-based diets.

In regards to lean animal protein, the 95% lean beef that Dr. Rodriguez promotes actually contains a similar amount of dietary cholesterol as that found in similar cuts of full-fat beef.16 Experiments on non-human primates have demonstrated that intake of even small amounts of dietary cholesterol as low as 43µg/kcal, the equivalent found in only half of a small egg in a human diet of 2,000 kcal induces atherosclerotic lesions. Furthermore, there was no evidence of a threshold for dietary cholesterol with respect to an adverse effect on arteries (Figs. 2, 3).20 21 Furthermore, several major prospective studies on humans found that dietary cholesterol was associated with a significant increased risk of all-cause mortality.22 23 24

Figure 2. Subclavian artery from a Rhesus monkey supplementing 43µg/kcal dietary cholesterol. Sudanophilia (black area) is intense in the area of major intimal thickening.

Figure 3. Fermoral artery from a Rhesus monkey supplementing 43µg/kcal dietary cholesterol. Intimal fibrous thickening and disruption of internal elastic membrane differentiate this artery from control vessels of monkeys supplementing 0 dietary cholesterol.   

Conflicts of Interest

Finally, Dr. Rodriguez’s financial tie to the livestock industry may explain why she appears to have misinterpreted the medical literature in regards to the disease promoting effects of animal foods and the nutrient density of plant-based foods, written in a largely textbook manner used by other livestock industry lobbyists. The tactics of the livestock industry may resemble those used by the tobacco industry that misinterpreted the medical literature in the past in order to dismiss the 'junk' science linking smoking to lung cancer and other associated diseases. Brownell et al. reminds us of how serious and real conflicts of interests can really be:25

A striking event occurred in 1994 when the CEOs of every major tobacco company in America stood before Congress and, under oath, denied believing that smoking caused lung cancer and that nicotine was addictive, despite countless studies (some by their own scientists) showing the opposite.

Perhaps the same can be said for Dr. Rodriguez’s claim that 'It is simply untrue to suggest that animal protein causes cancer', which is clearly in discordance with the preponderance of evidence. It maybe largely explained by socioeconomic factors as to why health authorities are unable to reach similar dietary recommendations as Dr. Campbell and his colleagues. For example, Eric Rimm from the Department of Nutrition, Harvard said to Reuters in regards to a major health report produced by the National Academy of Science, which he was an author of that:

We can’t tell people to stop eating all meat and all dairy produces. Well, we could tell people to become vegetarians... If we were truly basing this on science we would, but it is a bit extreme.

As Dr. Rodiguesz’s herself stated, 'appreciating the science behind nutrition helps us make smart choices about the best way to feed ourselves and the world'. Unfortunately her scare tactics illustrated in The Wall Street Journal demonstrated very little appreciation of the preponderance of scientific evidence.

Please post any comments in the Discussion Thread.