By Dan Lukaczer, ND

Q I’ve had kidney stones a couple of times in the past few years. My doctor says they come from calcium oxalate and that I should drink more water. Is there anything else I should consider?

A If you’ve had any type of kidney stone more than once, I would put you in the category of a recurrent kidney- stone former. Thus, your chances of having a repeat episode are high. You’re not alone. More than 500,000 Americans per year suffer from kidney stones. For a man, the chance of developing a stone is one in 10 over the course of his life. For a woman, the chance is somewhat less.

You mention your kidney stones are the calcium-oxalate variety—the most common stone by far (other types are struvite, uric acid and cystine). Studies show the creation of these stones is related to diet, particularly to eating oxalates. There are a number of foods that contain natural oxalates, with the highest amounts found in spinach. Rhubarb, beets, nuts, chocolate, tea, wheat bran and strawberries also have oxalates, and all should be limited in the diet when this type of kidney stone is a problem.

Additionally, it is important to increase the solubility of oxalates in the urine so they don’t crystallize and form stones. As your doctor suggested, you should make a habit of drinking plenty of water each day so you stay well hydrated. A rule of thumb is to drink at least eight glasses per day. There are also specific nutrients that appear to help, with magnesium, potassium and B6 leading the list. A recent study that analyzed chronic stone formers who took approximately 500 mg of magnesium oxide and 5 g of potassium-sodium citrate for one week found that oxalate crystals in the urine—a warning sign of potential stone formation—decreased by two thirds.

Lastly, the old rumor that it’s important to keep calcium low in the diet has been proven incorrect. In fact, just the opposite is true: research shows that increasing dietary calcium can decrease the incidence of calcium oxalate stones in recurrent stone formers, in part, at least, by binding oxalates from food.