Also, as to the original question of the thread, you can also have them try alfalfa sprouts, which act as a natural diuretic (like a water pill). Diuretics are the best treatment for high blood pressure because they don't have any side effects (except that you urinate more), where the more powerful MAOIs and such have rather nasty side effects.
Except that dehydration is a main cause of high blood pressure. If you have enough cellular potassium your body's cells will be hydrated, allowing normal blood pressure. Lack of cellular potassium causes cell dehydration and build up of acids, forcing the body to increase extra-cellular pressure to cope, and your blood pressure goes up. Blood potassium levels are easy to check but cellular potassium is what's important and usually not tested.
One type of blood pressure medication is just a potassium compound, and I think the American Heart Association says eating a high potassium diet is the most effective treatment for high blood pressure, along with exercise.
All the electrolytes are inter-related. Calcium speeds the heart, mgnesium slows it down. Calcium supplements can deplete your magnesium levels, causing cramps, racing heart beat and suicidal depression.
Potassium is needed at a 4 to 1 or more ratio to sodium, which is about 20 times less prevalent in natural foods. So the body hoards sodium naturally and depletes potassium when too much sodium is present. Salt 300 years or so ago was potassium salt. Now it is sodium, but you can buy Morton Lite salt that is a mixture of potassium chloride and sodium chloride. They have another version that has no sodium. If you mix the two you can get about a 4 to 1 ratio.
SOLO sea salt from England has reduced sodium levels (natural sea salt is mostly all sodium chloride) and added magnesium and potassium salts for what they say is an ideal balance. They say there is not enough magnesium and potassium in food because of depleted soils. Here is their link.
http://www.soloseasalt.com/what-is-solo.asp
Remember, one high sodium can of soup, tv dinner, or whatever can give you close to 1000 milligrams of sodium meaning you'd have to eat 4 grams of potassium to compensate. That's about 15 baked potatoes, or 5 bananas worth.
Potassium deficiency is also considered by many to be the major cause of arthritis, by causing dehydration of the tissues.