Salt Intake and Kidney Stones

Most individuals think that their calcium and oxalate intake are the main culprits to the formation of their kidney stones.  Because the most common kidney stone type is composed of calcium oxalate, this would seem to suggest that restricting calcium (in dairy products and supplements) and oxalate (in green leafy vegetables, tea, and chocolate, among other items) is the key to preventing stones. However, research has found that lowering the intake of salt (sodium chloride) and animal protein is actually more effective in preventing stones. A high sodium intake increases the risk of stone formation by increasing calcium levels and decreasing citrate (a stone inhibitor) levels in urine. These altered levels make it easier for stones to develop. Additionally, for patients on medications to prevent stones, a high sodium intake will impair the ability of medications such as hydrochlorothiazide to effectively reduce calcium levels in urine.

A five-year study of stone formers who were kept on a reduced sodium intake of 1200 mg a day in addition to a reduced animal protein intake diet demonstrated that a low sodium, low protein, and normal calcium intake diet was more effective in reducing stone recurrence by 50% as compared to a low calcium diet alone. The low sodium, low protein, normal calcium diet led to lower levels of calcium and oxalate in the urine as compared to a low calcium diet which translated into the fewer stones seen on this diet.

The average intake of sodium in the United States is 3500 mg per day. We recommend that stone formers aim to follow the FDA’s guideline of limiting their sodium intake to 2300 mg a day in the general population and 1500 mg of sodium a day in those with hypertension, African Americans, or middle aged and older adults. 2300 mg is equivalent to about 1 teaspoon of table salt. Our recommendation is less stringent than the 1200 mg of sodium a day limit used in the study discussed above because it can be difficult for most stone formers to limit their salt intake to that extent.  However, if you are able to decrease your intake to 1200 mg, that may reduce the number of stones you form further. The best way to determine the sodium content of your food is to read the nutrition label. Processed foods tend to contain higher amounts of sodium. Choose lower sodium options whenever possible.

  • 1 cup of canned chicken noodle soup contains 870 mg of sodium
  • A fried chicken drumstick contains 310 mg of sodium
  • A serving of shrimp contains 240 mg of sodium
  • 2 slices of white bread contains 200 mg of sodium
  • 15 potato chips contain 180 mg of sodium
  • 1 container of strawberry yogurt contains 85 mg of sodium
  • 1 tomato contains 20 mg of sodium

In addition to lowering the risk of stones, a low sodium intake helps to control or prevent high blood pressure, which can lead to heart disease, stroke, heart failure, and kidney disease.

References:

Borghi and colleagues: “Comparison of Two diets for the Prevention of Recurrent Stones in Idiopathic Hypercalciuria”; The New England Journal of Medicine, 2002.

 

About Dr. Mike Nguyen

Mike M Nguyen, MD, MPH, is a urologist and an Associate Professor of Clinical Urology at the Keck School of Medicine of USC in Los Angeles, CA. He specializes in the treatment of kidney stones with both surgery and dietary prevention and the in the treatment of kidney and prostate cancer using the latest robotic surgical approaches. He sees patients at clinics located in Los Angeles, Pasadena, and La Canada, CA. He is the founder of the www.KidneyStoners.org website.
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8 Responses to Salt Intake and Kidney Stones

  1. Ramesh says:

    due to aĺlergic problem if I eat lemon or any cool items I gei itching in nose and sneezing .Dr advice to take Montal tablet to take 6 months continously.since I am kidney stone patient can I continue this sodium contain tablet for 6 months.this tablet will not form

  2. Kathleen Flatley says:

    The problem with the control with was that it was a low calcium diet. It should have been a high calcium diet. The beneficial effect may have come from the normal calcium intake. Low calcium diets are no longer recommended as standard treatment for kidney stones.

  3. Charles Sherrer says:

    The elevation or reduction of meat intake also represents an additional reduction of sodium because nearly all processed meats have massive amounts of sodium. The cumulative volumes of sodium consumption is the elefant in the room.

  4. Jeff says:

    Low sodium and a low protein does not sound like a viable option. Comon, low protein? How can that possibly be healthy. That would mean a high carb diet with minimal protein. I can see lowering sodium, but low protein doesn’t sound like a very healthy way to eat.

    Anyone who eats low carb or paleo and is actively exersizing for improved fitness would be out of luck with such a diet.

  5. Paul says:

    Yes,
    I recently had passed a stone, horrible pain. Took 5 days, but I think it was there moving causing pain longer. About 4 months ago had triple bypass, no I have never had kidney stones and I am 60. Well after my operation I was put on effient for clotting, Aspirin, simvastatin for cholesterol, and metroplol for blood pressure, I then about 1 month noted cloudy urine and sediment. I started drinking more water and show my doc. Then checked and said my urine and blood were normal. So I didn’t worry. I kept checking my urine and looked cludy one day clear the next sometimes redish particles. So about 1 week agonmy back started hurting I didn’t think anything of it, but on Friday I started peeing blood tinted urine, I went to the doc on a Saturday, they did a CT SCAN, found a 4 mm stone, I was told to drink water and take flomax, then last night Tuesday I passed the stone. Really doctors are idiots, well some at least. I would suggest you check your urine daily drink tons of water, if your on meds drink 32oz of water with it. I knew there were crystals in my urine, I could see them reflect light. Even had a blood test vand urinalyses and was negative.

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  7. Vitor Ribeiro says:

    The problem wasn’t the intensity of the pain but the relentless duration. It’s enough to drive someone crazy. I was literally moaning at a point.

  8. the bad app says:

    Thanks for sharing your thoughts. I truly appreciate your efforts and I am waiting for your further post thank you once again.

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