THE KIDNEY STONE DIET

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If we put together everything on this site about diet for kidney stone prevention we get a reasonable and consistent image of one basic pattern. It is more or less what is ideal for idiopathic hypercalciuria and for reducing urine oxalate. It is the diet that has been used in the one major trial of diet for stone prevention. It accords with modern recommendations for the health of the American people. More or less, after all is said, there is only one diet plan that meets the needs for kidney stone prevention and we have called it ‘The Kidney Stone Diet.’

Of course, we are speaking of the diet for treatment of idiopathic calcium stones. Stones from systemic diseases, like bowel disease, primary hyperparathyroidism, primary hyperoxaluria, are treated by treating those diseases, and that is a different matter altogether. But those are the exceptions. Of the millions of American people with stones, almost all are idiopathic.

There will be surprises. Diet oxalate always matters but less so than you might think once the full diet is in place. Calcium will seem odd to you unless you have been a frequenter of this site. Sodium will seem all too familiar.

Dissecting the Diet

Calcium

High calcium intake is essential for stone formers. They have bones and many have idiopathic hypercalciuria that can cause bone disease unless there is a lot of diet calcium intake. Oxalate absorption is greatly hampered by high calcium intake, if the calcium is eaten when the oxalate is eaten.

It is not only stone formers who need a lot of calcium. The new FDA diet recommendations include high calcium intake for all Americans.

How high is high?

More or less, throughout life, men or women, girls or boys, the range hovers between 1,000 and 1,200 mg daily. This amount of calcium is ideal for both protection against bone mineral loss from idiopathic hypercalciuria and reducing oxalate absorption. The unique part for stone formers is timing the calcium to go with the main oxalate containing foods during the day.

Sodium

Urine calcium follows urine sodium like a shadow. The lower the sodium the lower the calcium. In the one bone study that seriously looked at the matter, it was the combination of low sodium diet and high calcium diet that led to positive bone calcium balance – uptake of mineral into bone as opposed to bone loss.

So, what is ‘low sodium. The new FDA recommendations are an intake below 2300 mg (100 mEq for those of you who read lab reports). For those with high blood pressure – treated with drugs or not – 1,500 mg is ideal. For stone formers, the latter, 1,500 is ideal because it brings urine calcium of hypercalciuric people near the normal range, and also benefits those without hypercalciuria by making urine calcium as low as possible.

If 1,500 mg is the ideal for the kidney stone diet, 2,300 is the absolute upper limit, and people will more or less want to live somewhere in between, hopefully at the low end.

Refined Sugar

Refined sugar is sugar that has been extracted from plants into the white stuff you buy in bulk and add to cake and cookie and brownie recipes, and use to make candy. The sugar in plants and fruits is packaged along with fiber and released slowly so it is very safe. Once you extract it into white powder it is absorbed very fast. We are not made to use this well. Blood sugar and insulin rise a lot, fat is formed, and it is not healthy.

Jack Lemann first showed decades ago that simply eating 100 gm of glucose causes a rapid rise in urine calcium with – can you imagine worse? – a concomitant fall in urine volume so supersaturations rise extremely high. It is the perfect storm. Urine calcium of people with hypercalciuria rises a lot more than in those without it, so it is evil in family members of stone formers. Since about one half of the relatives of a hypercalciuric stone former will be hypercalciuric because of genetics, even the children are put at risk by high sugar intakes. The worst part is that hypercalciuria is silent until stones or crystals form, so no one can know.

Very reduced refined sugar intake is emphasized in the new government diet recommendations because of American obesity and diabetes. The recommendation is that less than 10% of all diet carbohydrates come in the form of added sugar which means very little sweets. This means sugars that are added to foods, not the natural sugars in fruits and some vegetables. The latter are absorbed more slowly and are safe. Obviously candy and cake and brownies and all the other good stuff is in the very bad category.

Protein

Our long and difficult review of the protein story make a main point. People absolutely need at least 0.8 gm/day per kilogram of body weight of protein and need no more than 1 gm/d/kg. WIthin that narrow range there is a measurable but modest effect of protein on urine calcium that can be neglected if sodium is controlled. So we see no physiological basis or trial evidence that ‘low protein diet’ is appropriate. By low we could only mean 0.8gm/kg/d. The one comprehensive kidney stone diet trial implies a low protein intake but in fact employed 93 gm of diet protein – which is a lot. The diet change was to make 40% of it be plant based. But there is no evidence that plant protein reduces stones or urine calcium compared to meat protein. Plant based protein sources are often rich in oxalate.

Oxalate

All things being equal we have advocated for a low oxalate intake between 50 and 100 mg daily. However Ross Holmes showed clearly that with very high calcium intakes such as 1,000 to 1,200 mg daily, absorption of diet oxalate is less and therefore the need for strict control is also less. In the one diet trial by Borghi diet oxalate was 200 mg/day but diet calcium was high and urine oxalate actually lower than in his contrast group with low calcium diet and less oxalate intake.

The ideal approach as best we can tell is to put in place the high calcium diet, aim for about 200 mg of oxalate, which is easier to accomplish than lower values, and measure the urine results. If despite high calcium intake urine oxalate is creating risk of stones then diet needs to be altered appropriately.

Some people seem to absorb oxalate more efficiently than others, so there are no fixed rules. Many have normal urine oxalate excretions without any diet change at all. Many who have undesirably high urine oxalate at their first labs will show a marked fall with the higher calcium intake and need no further restrictions.

Some will remain hyperoxaluric despite the calcium and it is for them that very restricted oxalate diets can be reserved.

One key is urine collections to see that calcium alone can accomplish for any one person.

The other key is timing. The diet calcium must come in the same meals that contain the bulk of the day’s oxalate. Without that precaution calcium might not work well in this regard.

Fluids

We have covered this topic completely. The urine volume you want is above 2.5 l/d, the amount of fluids needed is about 3 l/d and you just have to experiment to find the exact intake for you, and also allow for weather, occupation, sports. Obviously sugared fluids have always been unfavored on this site, and you need to avoid them. The other major issue is steadiness over the day and into the evening. Overnight we just take our chances in most cases.

There You Have It

The kidney stone diet is one thing: High calcium, low sodium, low refined sugar, normal protein, flexible oxalate management that depends on how high urine oxalate is once high diet calcium is achieved, and of course high fluids.

This site is rich in articles that pertain to the kidney stone diet – it was built in part for this purpose. The home page lists articles by topic and you can find there the ones you need. Here is a brief summary with links.

High calcium and low sodium: 1,000 to 1,200 mg calcium 65 – 100 mEq (1,500 to 2,300 mg) sodium and care about oxalate (50 to 200 mg/day) can be achieved using our list of foods that meet all three requirements. It is essential that calcium be taken in with the meals that contain appreciable oxalate.

Low refined sugar (below 10% of daily carbohydrate intake): This is best thought of as a major reduction in sweets – cookies, candy, sugared drinks, cake, pie. Fruits are not a problem, but smoothies that break up the fruit may liberate their sugars and overcome the ‘slow release’ properties of the intact fruits themselves. We did not write an article about this matter because it is simply to give up what many of us love.

Normal protein intake – this translates into 1/2 to 2/3 pound of meats daily for an average adult. For stones, the issue of red meat vs. fish or chicken does not matter. Vegetable protein sources such as soy are high enough in oxalate one cannot recommend them.

High fluids and how to get them are in many articles on this site.

When Do You Begin the Diet

To us there is no question it should be after even one stone. The diet accords with all modern recommendations. The only special features are attention to oxalate and to timing of calcium with oxalate containing foods. High Fluids are more of a task, but after one stone the one trial showed a marked reduction in second stone formation with urine volumes above 2.5 l/day compared to the 1 l/d of the control group.

A more subtle matter is family members. Idiopathic hypercalciuria causes both stones and bone disease, and is hereditary. About half of first degree relatives of hypercalciuric people with stones have the trait even without stones. Given this, and also that the kidney stone diet is benign and in line with what we all should be eating, why not make it the general family diet as well?

I (Jill), have recently put together a private FB page called THE Kidney Stone Diet.  It is a group that helps educate you on your physician prescribed treatment plans. I moderate it to keep it clinically sound.  Come on over and join the discussion!

147 Responses to “THE KIDNEY STONE DIET”

  1. Gayle

    My husband has been plagued by recurrent kidney stones. Passed another one this morning. Is there any imaging that can be performed to see if he has other stones in his kidneys? We will work on the dietary suggestions in your article.

    Reply
    • Fredric Coe, MD

      Hi Gayle. CT scanning is nearly perfect but involves radiation; ultrasound is the common way to track if obstruction is present. Plain KUB x rays are poor but usable in some patients. Do pursue prevention; it works. Regards, Fred Coe

      Reply
  2. Kenny

    Hi Dr. Coe,
    I eat a very health-conscious diet, and I have been able to lower Ca 24 significantly by carefully following your dietary recommendations. But SS CaP I still too high. I’ve noticed that P 24 varies quite a lot between 24-hr urine tests, so I suspect that it may have to do with what I eat. But I haven’t been able to figure out a pattern.
    Can you please suggest how I can reduce P 24 and therefore also SS CaP through diet or something else? Thx!

    Reply
    • Fredric Coe, MD

      Hi Kenny, that SS CaP stays high means urine pH is too high, or volume too low, or calcium too high; the urine phosphate plays little role. So try to push volume up as best you can, lower sodium the same; in the worst case, if SS CaP is not 1/2 of less of what it was when you started and a bit more effort cannot achieve such a goal, perhaps your physician might want to add a very low dose of chlorthalidone – 12.5 mg/d if indicated. Regards, Fred Coe

      Reply
  3. Karessa

    I just passed my first stone and have 3 small calcifications. I also have interstitial cystitis so I can do no citrus and already have a very limited diet. I do very little dairy because it is so constipating. I eat zero processed sugar but have lived on spinach, sweet potatoes and meat for the past 3 years. My urology APN has me on 3g of DMannose daily (1.5g morning and evening). Is that a sugar that is ok on the stone prevention diet?

    Reply
    • Fredric Coe, MD

      Hi Karessa, With a low calcium diet + spinach you are almost asking to make a stone. The oxalate in spinach is very high and without diet calcium absorption will be very efficient. The mannose could reduce urinary tract infection but is itself of no known value or harm to humans. Here is a very detailed article about the matter. You need a different diet – kale instead of spinach would be a good start. You have a skeleton, so low calcium diet is a worry. Regards, Fred Coe

      Reply
      • Karessa

        Thank you Dr. Coe for your rapid response and the link to the article. And for the articles on the site that I am gradually making my way through. I will not be concerned about the DMannose and will continue supplementation if I understand the article correctly. It was a calcium oxalate stone that I passed. 24 hour urine and blood tests will be done in a couple weeks. I have already replaced spinach with kale, only eat 1 small sweet potato per week (had been daily) and have reduced salt and protein intake. I have increased water intake to approximately 2.5 liters a day and am still trying to increase. Your articles have been of great help! I am now trying to identify calcium sources that work with IC and are not horribly constipating. I plan to try cottage cheese this weekend.

        Reply
        • Fredric Coe, MD

          Dear Karessa, The ideal is the entire kidney stone diet – all five parts. Otherwise you will be forever overdoing one or another part – like too much attention to oxalate. Regards, Fred Coe

          Reply
  4. Mr Man

    Good day
    I am a 34 year old male from South Africa.
    On 1 April 2018, I had a huge amount of pain on my lower right back area and also groin area. I initially thought I was constipated but I also noticed that I could not urinate.
    I then rushed to the hospital and received the diagnosis that my urine contains some blood and that the scan showed that I had a kidney stone near my bladder area. I was then given one day / 24 hours to see if the stone can pass through.
    Unfortunately it did not. I then a had a procedure to remove the stone via a laser. I too have a stent which will be removed soon.
    I tried to understand what my cause was. I did not that I drank alot of Sugar-Free Pepsi soda on 1 March 2018 until 1 April 2018. I suspect this may have caused the issue? I also noticed that I drank alot of coffee particularly nespresso or similar.

    Questions I have:
    1. Can Soda cause kidney stones?
    2. Can Coffee cause kidney stones?
    3. Is there a diet I should be following to prevent? I understand drinking enough water daily assists this.

    Thank you

    Reply
  5. Tammy Alvarado

    I need to know about a site as well..
    I do not want to go there this again ..
    Please give me some info ..

    Reply
  6. Nina

    Hello,

    I am a 32 year old female who suffers from Calcium oxalate stones and I am on my way to get a procedure to remove them all. I have stents on each side bcuz an infection brewed up. I need guidance on what to eat and how to avoid this again. I’m miserable. If you can offer any advice please do. Thank you in advance .

    Reply

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