Epidemiological studies are often quoted to show the advantages of different diets. The only problem is that these studies can never show cause and effect. All they can do is show an association.
An association is a great starting point though. It can give you a hypothesis. For example, the Tarahumara Indians do not die of cardiovascular disease (CVD). They have a great many associated characteristics. Among possible associations is their game of kickball in which they run up to 200 miles over several days. They also eat a lot of corn and beans. Or maybe they have unique genetics. These are all associations from which to form a hypothesis. But none of these characteristics can be considered the cause of their lack of heart disease until many other studies are done.
Often an epidemiological study is presented as if it proved whatever the researchers propose as an explanation (hypothesis). However, a single study needs to be put into a framework of other studies so it can 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 levels it can include other epidemiological studies, as well as experimental studies on humans.
For studies of the health effects of the potassium to sodium ratio of ingested food, the studies would include how potassium and sodium affect the cell, various tissues and organs, and how different potassium sodium ratios affect people. A great many such studies have been done for the potassium sodium ratio. These studies provide a logical framework into which the many studies fit perfectly.
Cellular, Tissue And Organ Studies Are Needed
At the cellular level, it is well understood how potassium and sodium flow in and out of the cell, and the effect of the ions on the various membranes and surfaces within the cell. There are multiple studies on the effect on calcium and other ions, and effect within various cellular compartments.
At the tissue and organ level, the relationship of the two ions has been extensively studied for its effects on muscle, nerve, and bone. The effect on kidneys and adrenals and the interaction with aldosterone, angiotensin and renin, as well as multiple other hormones, has been well established.
Experimental And Epidemiological Studies Are Needed
There have been multiple short term experimental studies on the effect of potassium and sodium on humans. These have shown how these ions influence hypertension, CVD, stroke, osteoporosis and kidney stones.
More and more long term studies are being reported. This blog discussed some studies showing the effect of changing the ratio in the food of Finland here.
Historical studies of primitive civilizations, as well as studies of present day native populations have shown the type of diet consumed before the modern diet. The potassium and sodium content of these diets is relatively accurately estimated. Estimates of the age and type of disease these populations had are also excellent. These 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. Many theoretical diets are based on only one or two of these major areas of study. The importance of the potassium sodium ratio has support in all these areas to give a consistent and clear story of why it influences so many areas of health.