Kidney Stones - Other Treatments

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Calcium Restriction in Certain Cases. Some calcium stone patients may need to restrict calcium, such as those whose stones are caused by genetic defects in which the intestine over-absorbs calcium. More studies are needed to define this group precisely.

Fiber-Rich Foods and Their Compounds

Fiber may be beneficial for people with kidney stones. In addition, some fiber-rich foods may contain compounds that help protect against kidney stones. A wide variety of high-fiber plant foods contain a compound called phytate (also called inositol hexaphosphate, InsP6, or IP6), which appears to help prevent crystallization of calcium salts, both oxalate and phosphate. Phytate is found in legumes and wheat and rice bran. (Soybeans are also rich in phytate but they are also very high in oxalates, so the overall effects of soy on kidney stones are not clear.)

Purine Restriction in People at Risk for Uric Acid Stones

A high intake of purines can increase the amount of uric acid in the urine, so those at risk for uric acid stones should reduce their intake of foods that contain purines. They include beer and other alcoholic beverages, anchovies, sardines, yeast, organ meats (e.g., liver, kidneys), legumes (e.g., dried beans, peas, and soybeans), mushrooms, spinach, asparagus, cauliflower, and poultry.

Oxalate Restriction in Hyperoxaluria

Most people with calcium oxalate stones should not avoid oxalate-rich foods unless the doctor specifically recommends a restrictive diet. Oxalate binds with calcium in the intestine, which may actually reduce calcium absorption. Some studies, in fact, indicate that eating foods containing oxalates and calcium together may reduce the risk of stones. Most of the foods that contain oxalates are very important for good health. Restricting oxalates may be particularly harmful in people with bowel disorders marked by malabsorption.

• Foods high in oxalic acid include beets, soy, beet tops, black tea, chenopodium, chocolate, cocoa, dried figs, ground pepper, lamb, lime peel, nuts, parsley, poppy seeds, purslane, rhubarb, sorrel, spinach, and Swiss chard.
• Foods containing moderate amounts of oxalates include beans (green and wax), blackberries, blueberries, carrots, celery, coffee (roasted), concord grapes, currants, dandelion greens, endive, gooseberries, lemon peel, okra, green onions, oranges, green peppers, black raspberries, strawberries, and sweet potatoes.

Role of Fats

Certain fats may play a beneficial or harmful role in specific cases of kidney stones.

Restricted Fats in Patients with Stones Associated with Bowel Disease. Patients who have stones associated with short-bowel syndrome should restrict their intake of fat as well oxalates. In such cases, calcium may bind to unabsorbed fat instead of to oxalates, which increase oxalate levels.

Fish Oil. Omega-3 fatty acids, which are found in oily fish like mackerel, salmon, and albacore tuna, have many health benefits but the most current evidence suggests they do not help prevent kidney stones. A 2005 study of over 200,000 adults found that increased omega-3 fatty acid intake did not reduce kidney stone risk.

Role of Vitamins

Vitamin B6. Vitamin B6, or pyridoxine, is used to treat people with primary hyperoxaluria, a severe inherited disorder. Patients should not try to self-medicate with vitamin B6. Very high doses (500 to 2,000 mg daily over long periods) can cause nerve damage with loss of balance and numbness in the feet and hands. Food sources of vitamin B6 include meats, oily fish, poultry, whole grains, dried fortified cereals, soybeans, avocados, baked potatoes with skins, watermelon, plantains, bananas, peanuts, and brewer's yeast.

Vitamin C. Ascorbic acid (vitamin C) may convert to tiny insoluble crystals called oxalates. People with hyperoxaluria (too much oxalate in the urine) should avoid vitamin C supplements. Even for men with normal oxalate levels, higher consumption of vitamin C (more than 1000 mg a day) may increase kidney stone risk.

Role of Minerals

Magnesium and potassium may help reduce the risk for kidney stones in men.

Stress Management Techniques

Because of an association between stress and kidney stones, relaxation and stress management techniques may also be beneficial.

Preventing Recurrence

Dietary Considerations. People with kidney stones appear to be more sensitive to certain foods than people who do not form kidney stones and need to make specific changes in their diet. They should work with their doctors to develop a dietary plan that fits their individual situation. Drinking plenty of fluids is important for preventing recurrence of any kidney stone.

Indications for Drug Treatments. If dietary measures fail then drug treatments may be helpful. A number of drugs are available to prevent recurrences of calcium oxalate and other stones. Allopurinol, thiazide, potassium citrate, and potassium-magnesium citrate have all been shown to inhibit stone formation. In addition, drug treatments can sometimes also help prevent other complications related to stones, such as osteoporosis.

Correcting Underlying Conditions Known to Cause Kidney Stones. It is also important to treat and correct, if possible, any underlying disorder that may be causing stones to form. Such disorders include distal renal tubular acidosis, hyperthyroidism, sarcoidosis, and certain cancers. To prevent calcium stones that form in hyperparathyroid patients, a surgeon may remove the affected parathyroid gland (located in the neck). In most cases, only one of the glands is enlarged. Removing it ends the patient's problem with kidney stones.

Review Date: 05/22/2006
Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital