One of the earliest studies (1) to clinically show that improving the potassium to sodium ratio can reduce the incidence of high blood pressure, cardiovascular disease and stroke was started in the 1970s. It has been an ongoing study since then.
Finland – Coronary Heart Disease Capital Of The World
In the 1960s Finland's men had the worst rate in the world of coronary heart disease mortality and among the highest rates of high blood pressure (hypertension). Along with other interventions felt to be helpful at the time, the government sought to reduce sodium intake in the diet. By screening and educating the public, and getting food manufacturers to reduce the sodium in some of their products, they were able to reduce hypertension, cardiovascular disease and stroke in Finland.
The public education also included exercise, weight reduction, smoking cessation, alcohol reduction, and saturated fat and salt reduction. But during the first 20 years the obesity rate increased, alcohol consumption in men increased and smoking in women increased. Despite that, during the 20 year period they were able to bring down blood pressure by 10 mm Hg and reduce the stroke rate by 60%.
Fewer Strokes With Salt Reduction
Salt reduction in the diet is felt to be an important contributor to the lowering of blood pressure and the number of strokes. The sodium consumed did go down and the ratio of sodium to potassium improved.
At the time the study started there was no emphasis on potassium in the diet by the medical community. Because a mixed potassium salt was substituted for some of the sodium salt, there was a greater lowering in the diet of sodium than of potassium. So even though the Fins lowered the amount of potassium they got, sodium was lowered more. This resulted in the ratio of sodium to potassium in the diet improving.
Only 30 More Years To Go
The Finnish diet did not improve much beyond the ratio improvement. And although they have had dramatic improvement in their salt intake and their rate of cardiovascular disease and stroke, researchers estimate it will be over 30 years until the salt intake gets down to the recommended level.
Similar to the U.S. the Finnish government advice to reduce sodium has resulted in people adding less salt to their meals. But manufactured food still contributes a lot of sodium to the diet. Only some foods have less sodium. Food that does not have a reduced amount of sodium is still a major part of the diet. The shift to more vegetables and fruits and less meat has been minimal.
More recent studies from Finland show that there are limits to what can be achieved by reducing sodium in the diet without increasing the proportion of high potassium foods. We will discuss some of the more recent studies next post.
For lists of high potassium foods, click here and look for the food group you are interested in.
1. Karppanen H, Mervaala E. Adherence to and population impact of non-pharmacological and pharmacological antihypertensive therapy. J Hum Hypertens. 1996 Feb;10 Suppl 1:S57-61.