Kidney stones form in the urinary tract from crystallized salts and minerals that build up in the kidneys. Diet and nutrition can affect the development of these crystals in some people. Individuals who have had a kidney stone are at a high risk for recurrence and may want to try dietary measures to prevent future stones.
Types
The most common type of kidney stones are calcium oxalate stones, which are formed from crystals of calcium and oxalates, a compound found in green leafy vegetables, berries, sweet potatoes, green beans, oranges, wheat bran and other foods. Another type of kidney stone, called a uric acid stone, can be formed from purines, nitrogen compounds that occur in some foods including legumes, alcohol, anchovies, sardines, organ meats, mushrooms and spinach. Struvite stones, cysteine stones and xanthine stones are other, less common, types that are not generally caused by diet.
Fluids
High fluid intake, 10 cups or more of liquids a day, can help prevent calcium oxalate and uric acid stones. For cysteine stone prevention, you should consume at least 16 cups of fluid, around a gallon, every day. Water is the best beverage to drink for stone prevention, but adding a little lemon juice, totaling 1/2 cup a day, to the water can increase citrate levels and help keep calcium oxalate stones at bay. Cola, cranberry juice, apple juice and grapefruit juice should be avoided if you've had calcium oxalate or uric acid stones in the past. Coffee and tea may be helpful in preventing all types of kidney stones.
Diet
People who have had calcium oxalate stones may find that limiting sodium to under 2,400 mg a day can help prevent a recurrence. Reducing protein to under 6 g a day can help prevent all types of kidney stones. Consuming foods high in potassium, such as banana, or taking a supplement with this mineral may also reduce the risk of another calcium oxalate stone. Avoiding foods high in oxalates may help for some people prone to calcium oxalate stones, but since only a small percentage of oxalates in the body come from diet, this may be unnecessarily restrictive. Individuals with uric acid stones may do well on a diet that avoids purine-containing foods.
Sensitivities
Some people have conditions that affect the development of kidney stones. People with short-bowel syndrome may want to avoid dietary oxalates and lower their fat intake, since dietary fat and oxalates increase their risk of stones. Individuals with a disorder called hyperoxaluria may also need to limit oxalates in order to prevent kidney stones.
Misconceptions
A common misconception is that limiting calcium in the diet will help prevent calcium oxalate stones. In fact, most people who get adequate calcium without consuming too much, over 2,000 mg a day, have a lower incidence of repeat stones than people following a low-calcium diet, according to the University of Maryland Medical Center.
