Kidney stones aren’t little pebbles like you’d find in your yard. They’re essentially salts, which are composed of a positive ion and a negative ion. Table salt, for example, is sodium chloride. The positive ion in table salt is sodium and its negative counterpart is chloride.

In the kidney stone equation, the positive ion in the equation is calcium, which is plentiful in your body—there are pounds of this element in your system right now making up bones and being taken in by the foods you eat. The negative ion can be either oxalate or phosphate.

Salts crystallize in a “drier” environment. Like table salt dissolves in a lot of water, calcium oxalate and calcium phosphate dissolve in a volume of urine. However, if you become dehydrated, the kidneys can produce a “crystal lattice” and become prone to forming stones.

Preventing Crystallization

Increasing the amount of fluids you drink is an important first step. More urine gives calcium and oxalate less of a chance of crystallizing. Once the crystal lattice is producing stones, every instance of dehydration makes the stone grow larger.

Remember: calcium is plentiful in your body. Three different hormonal systems regulate how much calcium your systems absorb and excrete. In rare instances, these hormones malfunction—discovering this requires a 24-hour urine test. All that being said, it’s usually not helpful to severely restrict the amount of calcium intake.

However, you can do something about the amount of oxalate that you ingest. The liver makes 70 percent of the oxalate in the body, but 30 percent comes from diet. You should restrict oxalate-containing foods:

  • Coffee
  • Tea
  • Colas
  • Chocolate
  • Green leafy vegetables such as spinach

This doesn’t mean that you can never have these foods again. However, it would be best to consume them in moderation.

In addition to reducing dietary oxalate, you should stop taking vitamin C and vitamin D supplements, as well as calcium supplements and antacids containing calcium. You should also reduce added salt in your diet, eat meat in moderation, and increase consumption of citrus.