The kidneys filter the blood to remove excess mineral salts and other wastes the body doesn’t need. They subsequently produce urine, which excretes these wastes through the urinary tract. Kidney stones form when the urine has such a high mineral content that it can no longer dissolve the particles. The insoluble portion forms crystals that clump together and form hard stones.
When kidney stones are very small, they may pass through the urinary tract without difficulty. Once they become large, they can become painful and, in some cases, cause blockage which must be treated medically. For some people, this is a recurring problem that can be controlled to by diet.
Before formulating a treatment plan, it is important to determine what type of kidney stones you have. There are many types of kidney stones, based on the mineral that the body is trying to excrete in the urine. Your physician can run tests to determine which kind of kidney stones you are prone to and prescribe appropriate treatment. A plan that works for one kind of stone (including dietary intervention) may not work for another.
About 80% of all kidney stones are composed a combination of calcium and oxalate. Calcium combines with oxalate in the intestines, which reduces the calcium’s ability to be absorbed.
Recommendations for Kidney Stone Sufferers
Adequate fluid intake is the most important preventive measure for those with recurring kidney stones. Fluid hinders the formation of stones by diluting the urine. At least 3 to 4 quarts a day of water is recommended. Another way to measure adequate fluid intake is drinking enough to produce about 1.5 to 2 liters of urine each day.
Some research has shownlemonade to be an effective way to prevent kidney stones, not only because of the increased fluid intake, but also because it contains a substance called citrate which acidifies the urine, inhibiting stone formation. Powdered mixes can be used if they do not contain sugar (too much sugar in the diet can also aggravate stone development by increasing urine calcium), or try mixing 1 cup of concentrated lemon juice with 7 cups of water.
A diet high in animal protein (beef, chicken, pork, fish and eggs) affects urinary content of both calcium and uric acid. People who are prone to kidney stones should avoid eating high amounts. Limit portions to four to six ounces a day.
Dietary Recommendations to Reduce Calcium Oxalate Stones
Excess calcium absorbed through the digestive system Is passed through the kidneys. High amounts of urinary calcium can form stones. A study conducted at Brigham and Women’s Hospital and Harvard Medical School found that limiting dairy foods in an effort to reduce kidney stones was misguided, but taking calcium in the form of a supplement did appear to increase kidney stone risk.
Keep in mind that not getting enough calcium is also linked to kidney stones, because calcium binds with oxalates in the intestine. Without adequate calcium, the excess oxalate ends up in the urine, increasing risk for oxalate stones. It is recommended to continue to get adequate calcium in the diet to maintain bone mass and prevent osteoporosis – about 800 mg per day for men and between 1000-1200 mg per day for women. If a supplement is recommended, calcium citrate is the best form.
Excess sodium can increase the amount of calcium excreted in the urine causing stones to form. Maintaining a sodium intake under 2400 mg/day is recommended. Use a salt substitute that contains potassium. Potassium can help reduce urinary calcium excretion, lowering the risk of stones. Potassium intake of 3500 to 4500 milligrams a day is recommended through food (not supplements)
Fiber intake, particularly the insoluble kind found in wheat, rye, barley, and rice, may help reduce the amount of calcium in the urine. Fiber binds with calcium in the intestine so the excess is excreted through the colon rather than through the urinary tract.
It is generally recommended to limit soft drink consumption, particularly dark sodas that contain phosphoric acid. Phosphorus and calcium compete for absorption in the intestine, and calcium that does not get absorbed will be removed as waste. New research has shown that some orange and lemon-lime diet sodas are beneficial for preventing stones as they contain citrate.
Recent research has shown the DASH diet, initially created to help those with high blood pressure, is beneficial also to kidney stone sufferers because it is high in potassium and fiber and low in sodium and animal proteins.
About Vitamin and Mineral Supplements
When vitamin c is metabolized in the body, oxalate is produced. Excess vitamin C can increase the amount of oxalate in the urine, therefore taking vitamin C supplements in excess of 500 milligrams is not advised for those with calcium oxalate stones.
Some research has indicated that a deficiency in the mineral magnesium can contribute to kidney stones. It is recommended to get at least 400 milligrams each day from food or supplements. Some physicians also recommend vitamin B6, which works with magnesium in the body to reduce oxalic acid.
Be sure to inform your doctor of any over the counter products that you are taking, including vitamin/mineral and herbal supplements. These should be included (or excluded) as part of the overall treatment plan for kidney stones.
