Our Paleolithic ancestors ate much more potassium and less sodium that we do. The World Health Organization has new Guidelines for lowering sodium and increasing potassium, which may reduce cardiovascular disease. That’s debatable, of course. I haven’t read the guidelines, but here they are:
The Linus Pauling Institute says fruits and vegetables are the best sources of potassium. Beans are also good, but you won’t be eating those on most versions of the paleo diet. WHO recommends similar natural sources, and against simple supplementation.