Keeping free of kidney stones

Q: A few weeks ago, I had a kidney stone. The experience was absolutely awful. Now I’ve heard that once you have one, you’re more likely to get them again. This thought terrifies me. What can I do?

Dr. Wright: Even though kidney stones are one of the most common urinary tract disorders, they are nothing short of agonizing for those who suffer from them.

Fortunately, there’s a lot you can do to keep your kidneys free from stones for good. To understand the best way to fight them, there are a few basic facts you need to know about kidney stones. First, two-thirds of all cases involve calcium oxalate stones. Traditional medicine tries to prevent these by calling for dietary calcium restrictions and sometimes diuretics.

But restricting calcium intake isn’t actually helpful in preventing calcium oxalate kidney stones at all. And it could even make the problem worse.

There are other nutrients you need to add, though and to limit. Vitamin A (not betacarotene) promotes healthy functioning of the urinary tract, so people who are deficient in it sometimes form kidney stones more easily than others. You’ll find vitamin A in most good general multiple vitamin and mineral supplements (which I advise everyone to take even when you supplement with individual nutrients).

Magnesium helps the body dissolve calcium so if you’re deficient in this mineral it can cause calcium to accumulate into deposits, which increases your risk of forming kidney stones. Decades ago, Harvard researchers found that taking magnesium along with vitamin B6 can reduce calcium oxalate stone formation dramatically.

You won’t normally hear me touting a meat-free diet. But vegetarians actually tend to form significantly fewer calcium oxalate kidney stones than meat eaters. There are a couple of obvious reasons. Vegetarian diets include more bulk and fiber, which lowers calcium output. And, vegetable protein contains fewer sulfur-rich amino acids than animal protein, and those amino acids promote calcium excretions. I’m not saying you should give up meat entirely, but it will help you to increase fiber sources in your diet, such as root vegetables, and to cut back on how much meat you eat.

Sugar and salt can also increase the excretion of both calcium and oxalate in the urine, so since you have a tendency to form kidney stones, you should definitely limit, if not completely eliminate, sugar and refined carbohydrates from your diet, and cut back a bit on salt.

But calcium oxalate isn’t the only type of kidney stone. The less common type are uric acid kidney stones. As with the calcium oxalate, cutting back your intake of animal protein while increasing bulk and fiber in your diet can help prevent them from forming.

And, in addition to the problem refined sugar can pose for you, we know that fructose can also increase uric acid excretion in the urine. Eating whole fruit doesn’t cause this problem, but drinking fruit juice or drinks sweetened with “high fructose corn syrup” does.

The basic kidney-stone prevention program I recommend includes limiting intake of meat, sugar, salt, and fruit juice, increasing dietary fiber, and supplementing with 10,000 units of vitamin A, 300 milligrams of magnesium citrate, and 100 milligrams of vitamin B6 each day. Even though studies have “dispelled the myth” that higher amounts of vitamin C promote calcium oxalate kidney stone formation, I’ve seen two such cases first hand. So if you take three or more grams of vitamin C each day, have your doctor measure your urinary oxalate.