Retrospective #8: Epidemiologically Speaking: Patterns of Health and Illness

The Diseases of Modern (Western) Civilization began about 10,000 years ago, co-incident with the transition from the Paleolithic to the Neolithic era. The nomadic hunter-gatherer discovered he could lead a more stable and stationary existence on a diet largely comprised of cereal grains. This was a major shift in the human dietary.

In 1880, with the transition from stone-ground to steel-rolled flour, it accelerated. After the turn of the 20^th century, Crisco introduced fake “vegetable oil” fats and later the highly processed corn and soy bean oils high in Omega 6 fatty acids. In the latter half of the last century processed foods became ubiquitous. Today, many believe these shifts are the principal cause for the patterns of illnesses and medical disorders with which we are now beset.

In modern times, epidemiologists, who by definition look for statistical patterns of health and illness in populations, have examined this change and associated factors in myriad retrospective studies.  They have observed the health and illnesses of populations exposed to the “Western diet” and compared them to peoples who have lived in relative isolation without exposure to the changing dietary patterns of the industrialized world.

Epidemiology, however, is a statistical “science,” and can only go so far. These studies typically show correlations in similar populations and differences in dissimilar populations. As we’ve noted earlier, however, correlation does not imply causation. According to Wikipedia, “Epidemiological studies can only go to show that an agent could have caused, but not that it did cause, an effect in any particular case” (emphasis added by me).

Nevertheless, in the early 1950’s noted physiologist Ancel Keys proffered his Lipid Hypothesis, based on selected data from a 22-country epidemiological study. In his original Six Country Analysis (1953), and later the Seven Countries Study, launched in 1956 and first published in 1978, Keys’s hypothesis implicated dietary fat, particularly saturated fat and cholesterol, in heart disease. Acceptance of his hypothesis grew quickly and allowed others, like the American Heart Association, to promulgate the AHA’s now well-known “risk factors” for heart disease.

It also led to the controversial “Dietary Guidelines for Americans” (see Retrospectives #2 & #3). The USDA/HHS Committee to write the latest of these 5-year guidelines (for 2020) was formed just three days ago (2/21/2019).

All of these “prescriptions” dispensed to the consumer were still, however, nothing more than simple hypotheses and assertions. Hypotheses must be tested and retested by randomized controlled trials to independently reproduce similar outcomes. And if the outcomes aren’t reproducible, they must be rejected as false.

There have been many large, lengthy (in time) and costly trials such as the Framingham Heart Study. These studies have continuously been revised, updated and reinterpreted and their outcomes disputed. Along the way, many medical researchers have come increasingly to view with skepticism the Lipid Hypothesis and its resultant restrictions on consuming fats, particularly saturated fat and dietary cholesterol. Many in the medical and nutrition professions now view those recommendations as deeply flawed and based on inadequate scientific proof.

Conversely, the Standard American Diet (SAD), and in particular the USDA’s Dietary Guidelines for Americans, which is 60% carbohydrate, have increasingly come to infer a causal relationship with various diseases and metabolic disorders, chief among them Metabolic Syndrome. But, again, correlation does not imply causation.

The term Metabolic Syndrome is relatively new on the scene. When first described in 1988 by Gerald Reaven in his AHA Banting Lecture, he called it Syndrome X. It is, Wikipedia says, “a combination of medical disorders that increase the risk of developing cardiovascular disease and diabetes. It affects one in five people, and prevalence increases with age. A 11/23/10 CNBC story in Reuters (this blog post was originally written in January 2011), said “More than half of Americans will have diabetes or be prediabetic by 2020.” “More than half. “I think they nailed it.

In the next Retrospective we’ll learn the clinical definition of Metabolic Syndrome and how is it diagnosed (and treated.) In fact, the next +/- 500 posts will suggest ways to treat it, to “Lose the Weight…and Save Your Life.”