Kidney Stone Types
Several types of kidney stones can form from mineral crystals in the urine. Calcium oxalate stones are the most common, and are made of calcium that binds to oxalate. Calcium can also bind with phosphate and create calcium phosphate kidney stones. Uric acid stones form from uric acid, which is a waste product that forms when purines are broken down. Struvite kidney stones form due to chronic infection of the urinary tract.
Drinking plenty of water is one way to prevent the formation of kidney stones. Water promotes more frequent urination, which flushes mineral crystals out of the urinary tract. This can prevent crystals from turning into kidney stones. Some liquids should be restricted on a kidney stone prevention diet. Avoid drinking large quantities of citrus drinks, as they contain high levels of vitamin C. Oxalate is a byproduct of vitamin C breakdown, which can result in the formation of calcium oxalate kidney stones.
Adding insoluble fiber to the diet is one way to prevent kidney stone formation. High-fiber foods contain compounds that can prevent stones from forming. Calcium salt crystallization is inhibited by a compound known as phytate, which can be found in legumes, wheat bran and rice bran. While most people can eat high-calcium foods without a problem, people with kidney problems or mineral absorption problems may have to limit their intake of calcium. If this is necessary, dairy products and dark, leafy vegetables should be avoided. Calcium supplements should also be avoided if calcium restriction is necessary to prevent kidney stones.
Food restriction may be necessary based on the type of kidney stone someone has had in the past. Someone with calcium oxalate kidney stones may be advised to avoid high-oxalate foods such as chocolate, sweet potatoes, instant coffee, wheat germ, rhubarb, raspberries and spinach. High-purine foods should be avoided if someone is at risk for uric acid kidney stones. Examples of high-purine foods include red meats and legumes. Foods high in vitamin C should be avoided if someone is at risk for calcium oxalate kidney stones. Foods with high vitamin C content include papayas, broccoli, citrus fruits and peppers.