Kidney stones affect more than 3 million Americans each year and are one of the most common problems of the urinary tract, according to the National Institute of Diabetes and Digestive and Kidney Disorders. Kidney stones don't usually cause serious medical problems, but they can be very painful. Following a reduced sodium and calcium diet has been investigated as a possible treatment for kidney stones.
Kidney Stones
Kidney stones form from the crystals that separate out of your urine in your urinary tract. For most people, chemicals in the urine prevent crystals from forming, but these chemicals do not seem to work for everyone. Kidney stones are made up of a combination of different molecules, but calcium stones are the most common, consisting of calcium and phosphate or oxalate. It is not quite understood how stones form, but certain food choices may increase risk in people who are susceptible to stone formation.
Sodium and Calcium
Sodium and calcium are two essential minerals your body needs to function properly. Sodium helps maintain fluid balance and is necessary for muscle and nerve function. Most Americans get more than enough sodium in their diets. Calcium is important for bone health and strength. It is also needed for muscle contraction and nerve transmission. The minimum amounts of sodium and calcium you need each day are 1,500 milligrams and 1,000 to 1,200 milligrams, respectively.
Diet and Kidney Stones
The reduced sodium and calcium diet has been investigated as a treatment method for preventing kidney stones in people susceptible to the formation of calcium stones. A 2003 randomized study published in "Reviews in Urology" investigated the effects of a low-calcium diet versus a normal calcium, low-sodium, low-animal protein diet on a group of patients with idiopathic hypercalciuria, a condition in which high levels of calcium are present in the urine, increasing the risk of kidney stone formation. The investigators found that both groups had a reduction in stone formation. But there was an increase in oxalate excretion in the low-calcium group and a decrease in oxalate excretion in the normal calcium, low-sodium, low-animal protein group. The investigators recommend a normal calcium, low-sodium, low-animal protein diet to prevent stone formation and suggest that a low-calcium diet be avoided. A 2010 study published in "The American Journal of Clinical Nutrition" also found that a low-sodium diet, without a reduction in calcium, helped prevent stone formation.
Reducing Your Sodium Intake
You can help limit kidney stone formation by reducing your daily sodium intake. A good place to start is to omit adding salt to your food during cooking and at the table. Eating more fruits, vegetables, fresh meats and grains, and limiting your intake of processed foods can also help you reduce your sodium intake. You should also read food labels, and include foods with less than 140 milligrams of sodium per serving.
References
- National Institute of Diabetes and Digestive and Kidney Disorders: Kidney Stones
- The American Journal of Clinical Nutrition: Effects of a Low-salt Diet on Idiopathic Hypercalciuria in Calcium-oxalate Stone Formers: A 3-mo Randomized Controlled Trial
- Urology: Normal-Calcium, Low-Sodium, and Low-Animal-Protein Diet for Stone Prevention
- Colorado State Univesity Extension: Sodium in the Diet
- Office of Dietary Supplements: Calcium
- MedlinePlus: Idiopathic Hypercalciuria
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