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

In the February, May and August 2013 McDougall newsletters, I presented readers with articles addressing the dangers of low-carb and Paleo diets. Please take this opportunity to read these articles.

Although the question as to whether a plant-based diet extends life expectancy is likely determined by the quality of foods used to replace animal foods, numerous proponents of low-carb and Paleo diets have claimed that diets that exclude flesh do not favor longevity, and are even likely to promote premature death. Whenever health benefits are observed in vegetarians, these proponents have often simply attributed this to other healthy non-dietary habits associated with vegetarianism.

In this article, I examine a number of these concerning claims, and review the literature addressing the life expectancy of vegetarians and health conscious omnivores. In addition, I address a number of important limitations of studies carried out on vegetarians, and in particular, how paradoxical findings can result as the direct consequence of participants adopting a vegetarian diet in response to deteriorating health.

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.

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. 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.

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. 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.

…

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.