Once your doctor finds out why you are forming stones, he or she will give you tips on how to prevent them. This may include changing your diet and taking certain medications. There is no "one-size-fits-all" diet for preventing kidney stones. Everyone is different. Your diet may not be causing your stones to form.
There are dietary changes that you can make to stop stones from continuing to form. Below are some tips.
Drink enough fluids each day.
If you are not making enough urine, your doctor will recommend you drink at least 3 liters of liquid each day. This equals about 3 quarts (about ten 10-ounce glasses). This is a great way to lower your risk of forming new stones. Drink more to replace fluids lost when you sweat from exercise or in hot weather. All fluids count toward your fluid intake, but it's best to drink mostly no-calorie or low-calorie drinks, such as water. You should limit the amount of sugar-sweetened or alcoholic drinks you have.
Knowing how much you drink during the day can help you understand how much you need to drink to produce 2.5 liters of urine. Use a household measuring cup to measure how much liquid you drink for a day or two. Drink from bottles or cans with the fluid ounces listed on the label. Keep a log, and add up the ounces at the end of the day or 24-hour period. Use this total to be sure you are reaching your daily target urine amount of at least 85 ounces (2.5 liters) of urine daily.
Doctors recommend people who form cystine stones drink more liquid than other stone formers.
Reduce the amount of salt in your diet.
This tip is for people with high sodium intake and high urine calcium or cystine. Sodium can cause both urine calcium and cystine to be too high. Your doctor may tell you to avoid foods that have a lot of salt. The Centers for Disease Control (CDC) and other health groups say not to eat more than 2,300 mg of salt per day. The following foods are high in salt and should be eaten in moderation:
- Cheese (all types)
- Most frozen foods and meats, including salty cured meats, deli meats (cold cuts), hot dogs, bratwurst and sausages
- Canned soups and vegetables
- Breads, bagels, rolls and baked goods
- Salty snacks, like chips and pretzels
- Bottled salad dressings and certain breakfast cereals
- Pickles and olives
- Casseroles, other "mixed" foods, pizza and lasagna
- Canned and bottled sauces
- Certain condiments, table salt and some spice blends
Eat the recommended amount of calcium.
If you take calcium supplements, tell your doctor. Make sure you are not getting too much calcium. On the other hand make sure you aren't getting too little calcium either. Talk with your doctor or dietitian about whether you need supplements. Good sources of calcium to choose from often are those low in salt. Eating calcium-rich foods or beverages with meals every day is a good habit. There are many non-dairy sources of calcium, such as calcium-fortified non-dairy milks. There are good choices, especially if you avoid dairy.
You can usually get enough calcium from your diet without supplements if you eat three-to-four servings of calcium-rich food. Many foods and beverages have calcium in them. Some foods and beverages that might be easy to include on a daily basis with meals are:
Eat plenty of fruits and vegetables.
Eating at least five servings of fruits and vegetables daily is a good idea for all people who form kidney stones. Eating fruits and vegetables give you nutrients that may help keep stones from forming.
A serving means one piece of fruit, one potato, or one cup of raw vegetables. For cooked vegetables, a serving is ½ cup. If you think you may not be eating the right amount of fruits and vegetables, talk to your doctor about what will be best for you.
Eat foods with low oxalate levels.
This recommendation is for patients with high urine oxalate. Eating calcium-rich foods (see table above) with meals can often control the oxalate level in your urine. Urinary oxalate is controlled because eating calcium lowers the oxalate level in your body. But if doing that does not control your urine oxalate, you may be asked to eat less of certain high-oxalate foods. Nearly all plant foods have oxalate, but a few foods contain a lot of it. These include spinach, rhubarb and almonds.
It is usually not needed to fully stop eating foods that contain oxalate. This needs to be worked out individually and depends on why your oxalate levels are high in the first place.
Eat less meat.
If you make cystine or calcium oxalate stones and your urine uric acid is high, your doctor may tell you to eat less animal protein.
If your doctor thinks your diet is increasing your risk for stones, he or she will tell you to eat less meat, fish, seafood, poultry, pork, lamb, mutton and game meat than you eat now. This might mean eating these foods once or twice rather than two or three times a day, fewer times during the week, or eating smaller portions when you do eat them. The amount to limit depends on how much you eat now and how much your diet is affecting your uric acid levels.
Changing your diet and increasing fluids may not be enough to prevent stones from forming. Your doctor may give you medications to take to help with this. The type of stone and the urine abnormalities you have will help your doctor decide if you need medicine and which medicine is best. Common medications include:
are for patients who have calcium stones and high levels of calcium in their urine. Thiazides lower urine calcium by helping the kidney take calcium out of the urine and put it back in the blood stream. When taking thiazides, you need to limit how much salt you take in, as these medications work best when urine sodium is low.
is for patients with calcium stones and low urinary citrate, and for those with uric acid and cystine stones. Potassium citrate makes the urine less acidic or more alkaline (basic). This helps prevent cystine and uric acid stones. It also raises the citrate level in the urine, helping to prevent calcium stones.
is frequently prescribed for gout, which is caused by high uric acid in the blood. Allopurinol not only lowers the level of uric acid in the blood but also in the urine, so it may also be prescribed to help prevent calcium and uric acid stones.
Acetohydroxamic acid (AHA)
is for patients who produce struvite or infection stones. These stones form because of repeated urinary tract infections (UTI). AHA makes the urine unfavorable for struvite stones to form. The best way to prevent stuvite stones is to prevent repeated UTIs caused by specific types of bacteria and to completely remove the stones with surgery.
Cystine-binding thiol drugs
are used only for patients who form cystine stones. These medications (d-penicillamine or tiopronin) bind to cystine in the urine and form a compound that is less likely than cystine to crystallize in the urine. This drug is used when other measures fail, such as raising fluid intake, reducing salt intake or using potassium citrate.
Take caution when using Vitamin supplements. Some can increase your risk of forming kidney stones. Your doctor and a dietitian may be good to ask about over-the-counter nutritional supplements.