Proponents often quote epidemiological studies to show the advantages of their favorite diet. The only problem is that these studies can never show cause and effect. All they can do is show an association.
But, an association is a great starting point. It gives you a hypothesis. For example, in the past, the Tarahumara Indians did not die of cardiovascular disease (CVD). They have a great many characteristics that are potentially associated with the lack of CVD. For instance, among possible associations is their game of kickball. They run up to 200 miles over several days in this game. Also, they eat a lot of corn and beans. Or maybe they have unique genetics. These are all associations from which to form a hypothesis. But you cannot consider these characteristics to be the cause of their lack of heart disease until you see many other studies.
The Need For A Framework
Often, proponents present an epidemiological study as if it proved whatever the proponents propose as an explanation. But the study only provides a hypothesis. In particular, a single study needs to be in a framework of other studies to be understood. The other studies should include basic related cell biology, and other laboratory studies at the tissue, organ and organism levels. At the organism level, it can include other epidemiological studies, as well as experimental studies on humans.
Consequently, for studies of the health effects of the potassium to sodium ratio of ingested food, the studies need to include how potassium and sodium affect the cell, various tissues and organs. Additionally, the studies should include how different potassium sodium ratios affect people. The potassium sodium ratio has a great many such studies. As a result, these studies provide a logical framework into which the many studies fit perfectly.
The Need For Cellular, Tissue And Organ Studies
At the cellular level, researchers understand how potassium and sodium flow in and out of the cell, and the effect of the ions on the various membranes, proteins, and surfaces within the cell. And they have produced multiple studies on the effect on calcium and other ions, as well as the effect within various cellular compartments.
At the tissue and organ level, researchers have studied extensively the relationship of the two ions for the relationship's effects on muscle, nerve, and bone. They have well established the effect of the ions on kidneys and adrenals, as well as their interaction with aldosterone, angiotensin and renin. And they have established the effects with multiple other hormones, as well.
The Need For Experimental And Epidemiological Studies
Furthermore, researchers have conducted multiple short term experimental studies on the effect of potassium and sodium on humans. These studies show how these ions influence hypertension, CVD, stroke, osteoporosis and kidney stones.
In addition, authors are reporting more and more long term studies. For example, this blog discussed some studies showing the long term effect of changing the ratio in the food of Finland in a prior post.
Similarly, historical studies of primitive civilizations, as well as studies of present day indigenous populations, have shown the type of diet consumed before the modern diet. The studies have estimated the potassium and sodium content of these diets relatively accurately. And the studies have produced excellent estimates of the age and type of disease these populations had. Such studies confirm the importance of the potassium to sodium ratio.
In future posts we will try to discuss each of these major areas in more detail. Often, only one or two of these major areas of study form the basis for many of the theoretical diets. The importance of the potassium sodium ratio has support in all these areas. And this gives a consistent and clear story of why the ratio influences so many areas of health.