A kidney stone is a hard mass that forms in your urinary tract as a result of separation of crystals from the urine. Normally, all of the substances in your urine remain in a solution. If the urine contains too much of a particular substance, such as oxalate or uric acid, the crystals may separate from the urine, causing a kidney stone to develop. Although proper diet cannot guarantee that you will not develop kidney stones, certain food restrictions can reduce your risk.
Calcium Stones
Calcium kidney stones form when calcium combines with other substances, usually oxalate, and forms a solid mass. Normally, the calcium and oxalate dissolve in your blood and filter out through your kidneys without any difficulties. If you have bowel inflammation, your body may not handle calcium and oxalate properly, and as a result, calcium oxalate stones may form.
Low Oxalate Diet
If you are prone to calcium oxalate kidney stones, you should limit your intake of oxalate to 40 to 50 mg each day. You should completely avoid high-oxalate foods, which contain more than 10 mg of oxalate per serving. High-oxalate foods include black tea, soy products, nuts, whole wheat bread, berries, kiwi, carrots, celery, eggplant, kale, leeks, sweet potatoes, spinach, black pepper and chocolate. Limit your intake of medium-oxalate foods, which contain 2 to 10 mg of oxalate per serving, to 2 to 3 servings per day. Medium-oxalate foods include orange juice, cranberry juice, yogurt, pears, peaches, liver, sardines, brown rice, oatmeal, white bread, broccoli, corn, lettuce, onions and tomatoes.
Uric Acid Stones
Uric acid stones form when your blood contains too much of the waste product uric acid. Uric acid forms when your body breaks down purines. Normally, uric acid dissolves in the blood and then moves to the kidneys, where it is removed from the body through the urine. If you are prone to uric acid kidney stones, the uric acid in your body does not dissolve properly. Instead, it remains in its full form and forms urate crystals, which can travel to the kidneys and become kidney stones.
Low Purine Diet
If you are prone to uric acid kidney stones, you should follow a diet that is low in purines. According to the University of Pittsburgh Medical Center, purine-rich foods make up 15 percent of the uric acid in the body. Eliminating foods that contain purines can help lower the amount of uric acid in your blood and reduce your chances of developing uric acid stones. High fat foods like avocados, pancakes, waffles, French fries, muffins and full-fat dairy products are high in purines. Other high purine foods include sardines, anchovies, scallops, mussels, mackerel and most desserts. You may consume beans and peas, which contain purines, but must limit intake to 2 servings per week.
Considerations
With any type of kidney stones, you should drink plenty of water throughout the day. Water can help promote urination, flushing out the body and increasing your chances of naturally removing kidney stones. MayoClinic.com recommends drinking 8 to 12 cups of water every day.
