High potassium foods have been shown to have favorable effects on cardiovascular and cerebrovascular health. Several studies of large populations have shown that when the potassium to sodium ratio is increased in the diet, blood pressure is lowered, and strokes and cardiovascular disease are reduced. A study in 2006 (1) showed that changing the potassium sodium ratio only slightly in the diet can have a big effect. This effect occurred without changing any aspect of the diet except the type of salt used, a potassium enriched salt.
The researchers simply changed the composition of the salt the subjects used so that it had as much potassium as sodium. The ratio of the potassium to sodium in the potassium enriched salt was 1 to 1. The group that received the potassium enriched salt had a 39% lower incidence of cardiovascular disease than the group using normal salt. They also showed 70% less heart failure. And they showed a 50% decrease in cerebrovascular disease.
This was one of the early long term studies that showed increasing potassium in the diet by simply replacing some of the sodium in salt with potassium could bring about improvements in cardiovascular disease, heart failure and stroke.
There had been several short-term studies of administering potassium enriched salts. In the 1970s Meneely showed the vascular protective effect of potassium chloride. Khaw and Barrett-Connors showed a reduced stroke mortality of 40% for every 10 mmol increase in potassium intake. Others have shown similar short-term effects.
But in this study the subjects were examined for a longer period – an average of 31 months. There were 20.5 cardiovascular deaths per year per 1000 persons in the group using normal salt. There were only 13.1 cardiovascular deaths per year per 1000 persons in the group getting the potassium enriched salt. The experimental group had 768 subjects and the control group had 1213 subjects.
The two groups were all elderly veterans in a retirement home who had their meals prepared for them. This provided uniformity to the meals. The increase in the percentage of potassium in the salt was done slowly over a three-week period to make the change in taste less noticeable. The meals were otherwise unchanged in composition during the time of the study.
The experimental group and the control group were highly matched for risk factors. Their age, height, weight, BMI, blood pressure, and urinary sodium and potassium were very close. 40% of each group were hypertensive prior to beginning the study. By matching the urinary sodium and potassium it could be assured that the diets were equal in sodium and potassium content prior to the change in salt. This way there was no selection for those who had a naturally higher potassium or naturally lower sodium intake.
In this study patients who were bedridden or who had poor kidney function were excluded from the study. This excluded those whose poor health might bias the results. Some other dietary studies of dietary sodium reduction and cardiovascular disease did not exclude such people, and thus had people in poorer health in the low sodium group. These studies concluded that low dietary sodium led to an increase in cardiovascular deaths. The correct conclusion should have been that people with worse cardiovascular disease have a greater likelihood of cardiovascular death, even when on a low sodium diet.
25% of the men in the study were able to be studied for their urinary sodium and potassium. There was no change in these ratios over the experimental period in the control group. On the other hand, the experimental group showed a decrease in their sodium from 1.34 to 1.22. Their potassium increased from 0.28 to 0.48.
The ratio of the potassium to sodium in the potassium enriched salt was only 1 to 1. As can be seen from the urinary ratios, the overall change in dietary potassium to sodium ratio was not very great. Nonetheless this gave a significant change in cardiovascular deaths. And this was despite very little change in blood pressure.
Previous posts discussed how the heart's ventricular function, heart cell function and vascular lining cell function change from a change in the potassium sodium ratio, even before there is a change in blood pressure. So this finding should not be surprising.
To reduce blood pressure, and to reduce the likelihood of cardiovascular and cerebrovascular death even more than in the study, a greater change in the potassium sodium ratio in the diet is needed. Most evidence indicates a ratio of greater than 3 to 1 is highly effective. This is difficult to achieve safely with potassium enriched salt, but easy with high potassium foods.
1. Effect of potassium-enriched salt on cardiovascular mortality and medical expenses of elderly men. Chang HY, Hu YW, Yue CS, Wen YW, Yeh WT, Hsu LS, Tsai SY, Pan WH. Am J Clin Nutr. 2006 Jun;83(6):1289-96.