Potassium magnesium citrate is a nutritional supplement that fights kidney stones in three different ways. The potassium provided by the supplement raises the pH of the urine, making it more alkaline, thus reducing the amount of calcium that the urine can dissolve. When there is less calcium in the urine, fewer calcium kidney stones can form. The magnesium in the supplement reduces the amount of calcium the kidneys pump out of the body and into the urine. And the citrate in the supplement keeps oxalates dissolved in the urine so they are flushed away before they can form kidney stones.
About 95% of the citrate in potassium magnesium citrate, however, does not reach the kidneys in the form of citrate. It is oxidized in the bloodstream to form bicarbonate, which raises the pH of the bloodstream and gives the kidneys less work to keep acids from forming as meat and dairy are digested. In this way, potassium magnesium citrate keeps calcium in bones and keeps it out of the urine where it can form kidney stones.
Potassium magnesium citrate can't be used by people who take amiloride, triamterene, spironolactone, ACE-inhibitors, or ACE-receptor blockers for high blood pressure. If you don't know whether your high blood pressure medication is one of these categories, ask your pharmacist before you take potassium magnesium citrate. It also interacts with many other medications for high blood pressure, arthritis, and chronic muscle pain, and also with aspirin. Don't use potassium magnesium citrate if you take aspirin or any other medication your pharmacist tells you may cause an interaction. It's also important not to take both potassium magnesium citrate and any other potassium supplement.
Could you emulate benefits of potassium magnesium citrate with juicing? You can, but it's tricky. Most of the green leafy vegetables that are highest in magnesium are also high in oxalates. Many of the fruits that are high in citrates are also high in sugars, which concentrate minerals in the urine. However, here's a combination that provides the minerals without the chemicals that can precipitate into kidney stones:
Combine freshly squeezed lemon juice (using a citrus juicer, never a macerating juicer, because of the high concentration of oxalates in lemon peel) with juices of tamarind, fig, prickly pear cactus, prunes, apricots, or peach. Or combine lemon juice with tomato or carrot juice. If you need to add sweetness, use powdered stevia rather than stevia extract.