Kidney stones are hard deposits that form in the kidneys as a result of a mineral or salt imbalance in the urine. Normally, your urine contains chemicals that keep all of the substances in a solution. If your urine contains excess amounts of a particular substance, it can throw off the balance and result in the formation of a hard crystal, or kidney stone.
Types of Kidney Stones
The most common types of kidney stones are calcium oxalate kidney stones and uric acid kidney stones. Calcium oxalate kidney stones form when the calcium in your urine combines with oxalate. Your body receives oxalate from your liver as well as the food you eat. Uric acid kidney stones form when your body breaks down substances called purines into a waste product called uric acid. Like oxalate, uric acid comes from your liver and your diet. If you consume too much oxalate or purines, the oxalate and uric acid in your urine can accumulate to abnormally high levels, increasing your risk of developing kidney stones.
Treatment
Most people are able to pass kidney stones without any medical intervention. Increasing fluid intake prompts your kidneys to produce urine, which can help speed the rate at which you pass the kidney stones. If kidney stones are too large to pass on their own, surgical removal may be necessary. Once kidney stones have passed or been removed, following a proper diet can decrease your chances of a recurrence.
Low-Oxalate Diet
If you are prone to developing calcium oxalate kidney stones, you should limit your intake of oxalate to 40 to 50 mg per day, according to the University of Pittsburgh Medical Center. You should eliminate high-oxalate foods, which contain more than 10 mg of oxalate per 3.5 oz serving. High-oxalate foods include black tea, soy products, whole-wheat bread, nuts, nut butters, berries, figs, carrots, celery, spinach, sweet potatoes, kale, leeks, Swiss chard, beans and chocolate. Your intake of medium-oxalate foods, which contain 2 to 10 mg of oxalate per serving, should be limited to two to three servings per day. These foods include beer, yogurt, peaches, pears, oranges, brown rice, cornmeal, oatmeal, asparagus, broccoli, onions, lima beans, corn and thyme.
In addition to avoiding foods that contain significant amounts of oxalate, drink eight to 13 8-oz. glasses of water per day. Water can dilute the concentration of your urine and help increase urinary frequency, which can decrease your risk of developing kidney stones.
Low Purine Diet
Purines account for approximately 15 percent of the uric acid in your body. Those prone to developing uric acid kidney stones should avoid foods that are high in purines, such as organ meats, fatty foods, bacon, venison, veal, anchovies, scallops, mussels, trout, haddock, gravy and yeast. You do not have to completely avoid foods that contain moderate amounts of protein, but limit your intake. Moderate-purine foods include chicken, pork, beef, shellfish and lunch meats. With a low-purine diet, most of your calories should come from fruits, vegetables, low-fat dairy products, nuts, nut butters, beans, potatoes, rice and pasta. Consume at least 12 8-oz. glasses of water or fruit juice throughout the day.
