General Dietary Recommendations for Kidney Stone Formers

1. FLUID INTAKE:

All stone formers should increase their fluid intake so that the urine output is more than 2 liters per day. This usually requires intake of more than 2.5 liters (3 quarts) of fluid per day and more on hot days when the patient has excessive sweating or diarrhea. The fluid intake should be spread out throughout the day and night. Patients should drink a large glass of water before bed and keep another by the beside to drink if he or she wakes up during the night. Fluids may be any type except those that contain milk or tea. Orange juice contains a large amount of citrate and potassium, so a large glass of orange juice daily may help prevent stones. Lemonade may also be a particularly good fluid because it also provides large amounts of citrate which can help to prevent stones. A simple recipe for lemonade is the following.

• Mix 4-6 ounces of reconstituted lemon juice with water to make 2 liters (a 2 liter bottle is a convenient container). Add sugar to taste.

• Patients should try to consume 2 liters of lemonade every day.

2. CALCIUM INTAKE:

Dietary calcium intake can play a role in kidney stone problems in some patients, and some patients may need to cut back on dairy products. However, severe calcium restriction is not necessary or effective for all patients with kidney stones, and may make the problem worse in certain patients. In addition severe dietary calcium restriction can result in weakening of the bones (osteoporosis). Therefore, most patients should cut dairy product intake to recommended daily allowance but not below this level, unless instructed to do so by their doctor. The main dairy sources of calcium are dairy products, meat, and green leafy vegetables. The recommended daily allowance of calcium is 1000 mg per day. Which represents 2-4 average servings of these foods? Examples of a single serving including an 8 oz. glass of milk, 1-2 ounces of cheese, or a small bowl of ice cream. If you eat very large amounts of milk, cheese, ice cream, meat or greens, then some limitations may be advisable. Patients should avoid extra-dietary sources of calcium unless instructed to take them by their doctor. These include Tums and Rolaids (other antacids that don't contain calcium such as Maalox or Mylanta are OK). Calcium fortified orange juice and calcium containing vitamins. Calcium supplementation in post-menopausal women should be discussed with their doctor.

3. SODIUM INTAKE:

Sodium (salt) excretion and calcium excretion into the urine are linked, so a diet that contains too much salt can cause kidney stones. All patients with kidney stones should eat a low salt diet which contains less than 2 gm (100mEq) of sodium per day. Patients should never add salt to their food with a salt shaker, and should avoid food high in salt. These include most fast foods, boxed or canned foods unless they are labeled low sodium, cheese, pizza, barbecued or cured meats, hot dogs and snack foods.

4. PROTEIN INTAKE:

A diet with a high protein intake, particularly animal protein (meat), can make a kidney stone problem worse. All patients with stones should limit their protein intake to 70gm per day. This usually means lowering all forms of meat and egg intake (including poultry, beef, pork and fish) to two average portions per day. It is almost impossible to eat a diet that is too low in protein.

5. OXALATE INTAKE:

A diet high in oxalate can be a problem for patients with kidney stones, but very few patients eat a diet that is too high in oxalate. The major dietary sources of oxalate are rhubarb, spinach, beets, peanuts, chocolate, parsley, celery, tea and coffee. Patients with calcium oxalate stones should limit their intake of these foods as much as possible.

6. LOW OXALATE BRAN:

There is evidence that intake of 10-15 gm per day of bran can lower the risk of stones in patients with too much urinary calcium. Wheat bran has the highest oxalate content compare to rice bran, soy bran and corn bran, so it may be preferable to avoid wheat bran if possible.

7. VITAMIN C INTAKE:

Vitamin C is metabolized into oxalate which can be part of calcium oxalate stone. The major dietary source of vitamin C is from citrus fruits, tomatoes, broccoli and brussel sprouts. It is extremely rare to get too much vitamin C from the diet, however, and citrus fruits contain citrate which may help patients with kidney stones. Patients who eat an unusual diet with a very large intake of one of these foods may want to cut back somewhat. Consumption of large doses of vitamin C in the form of pills should probably be avoided.