Thirteen percent of North American men and seven percent of women suffer from kidney stones which can be incredibly painful to pass from the kidneys to the bladder. Those who get one stone have a 50 percent chance of passing another stone within the next five years. Here are the current recommendations for preventing kidney stones:
• Drink enough water to make you urinate at least eight cups of urine per day. This is the most effective way to prevent kidney stones. Do not waste your money on expensive low-mineral waters; they offer no advantage over ordinary tap water.
• Follow a high-plant diet such as the DASH (Dietary Approaches to Stop Hypertension) diet because many studies show that this type of diet helps to reduce kidney stone recurrences. The DASH diet is high in fruits and vegetables, and restricts animal protein and whole milk dairy products. Any diet that follows these guidelines will be equally effective.
• Avoid soft drinks that contain phosphoric acid, which can increase stone formation. Read the list of ingredients. Drinks that are acidified with citric acid are far less likely to cause stones.
• Restrict salt. Sodium increases urine calcium concentration which can combine with oxalates or phosphorus to form stones. Reducing sodium intake is more effective than restricting calcium in preventing kidney stones. Restrict salty foods such as meat, canned soups and fast food, and avoid adding salt to your food. Read labels to check sodium content. Also avoid other forms of sodium: monosodium glutamate, sodium bicarbonate, disodium phosphate, sodium alginate and sodium nitrate or nitrite.
• Avoid being overweight. Excess weight increases risk for kidney stones.
• People with a history of kidney stones should not take calcium pills. However, calcium from food has not been shown to increase risk of calcium oxalate stones. Calcium in the digestive tract binds to oxalates from food which keep it from entering the blood and then the urinary tract where it could form stones.
Types of Stones
Kidney stone types include:
• Calcium oxalate stones, the most common type, associated with high urine concentration of calcium and oxalate
• Calcium phosphate stones, associated with increased urine calcium and alkalinity
• Uric acid stones, associated with increased urine acidity and uric acid
• Struvite stones, caused by urinary tract infections
• Cysteine stones, which are genetic
Nobody has shown that recommendations based on testing for the type of stone reduce recurrent stone formation. However, people who have experienced the pain of a kidney stone will try just about anything to avoid having it happen again. Recommendations based on specific types of kidney stone include:
• Calcium Oxalate Stones: Restrict salt and animal protein; animal protein increases urine excretion of calcium. Do not take calcium pills. Restriction of oxalate-rich foods is still controversial. Your body makes oxalates from the food that you eat, and eating foods rich in oxalates (such as spinach, rhubarb, nuts and wheat bran) can increase oxalates in your urine. However, most oxalate-rich foods are healthful and anti-inflammatory. No one has proven that avoiding them prevents kidney stones.
• Calcium Phosphate Stones: Restrict salt and animal protein; do not take calcium pills
• Uric Acid Stones: Restrict animal protein. Purines found in animal proteins (meat, poultry, fish, eggs) break down into uric acid that can bind to calcium to form stones. Low-carbohydrate diets increase risk for uric acid stones.
Check blood and urine levels of calcium. Having high blood and urine calcium levels increases risk for kidney stones. A blood test for parathyroid hormone can rule out a highly-curable parathyroid tumor that can cause high blood calcium levels.
People who have had several attacks of kidney stones may benefit from taking thiazide diuretics, citrate or allopurinol. Taking all three drugs has not been shown to be more beneficial than taking just one. No data show that one brand of thiazide diuretic is better than any other. Side effects include dizziness, belly cramps, fatigue and muscle cramps. Citrates can cause belly cramps and allopurinol can cause a low white blood cell count.