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!

198 Responses to “THE KIDNEY STONE DIET”

  1. Biome Onboard Awarness

    When will you confirm that oxalate neutralizing microbiome species are increased when eating the oxalate foods, while also consuming calcium to protect the kidneys from excess oxalates (along with the other factors of the University of Chicago Kidney Diet)? My post, “Kidney Stones, food” shows a Litholink (24 hour urine testing for kidney protection) chart over time. It repeatedly show higher oxalates with lower dietary calcium. As well, it demonstrated great solutions when eating your diet at home vs worsening with return to college cafeteria foods. I’m sure you have this effect demonstrated in your patient records as well!?! Have you published this?

    Reply
    • Fredric Coe, MD

      Hi, I really should not allow this post on the site as it is advertising a product. Multiple studies have documented falling urine oxalate with higher diet calcium, so rising urine oxalate with falling diet calcium is predictable – in fact the same thing. I know of no oxalate neutralizing species; I know about microbes that metabolize oxalate, that they do not flourish unless one provides oxalate, and that the few trials have been bleak failures so far. I do not endorse your products. Fred Coe

      Reply
  2. Nickie

    What is the exact play by play diet for a male to follow to get a kidneystone that is lodge I’m his kidney and needs the stone to by through right away asap?? Tyia

    Reply
  3. Doug James

    I would like to join a private group but not on Facebook or Google for security (and political) reasons as neither of these can be trusted, a software engineering fact.

    Reply
  4. Dennis

    Thanks for putting this together! I have been attempting to follow this. I am finding the oxalate, calcium, added sugar and sodium restrictions to be doable. However, I am far exceeding the top of the protein range (about 2.6 g of protein per kg of body weight) and am about 700 calories below where I’d like to be (2,500) given my activity level and weight. Any recommendations for foods to add?

    Example:
    Breakfast: Oatmeal, Blueberries, Skim Milk, Banana
    Lunch: Turkey Burger on thin Bun, Salad, Skim Milk
    Dinner: Boneless Skinless Chicken Breast, Cooked Vegetables, Cottage Cheese, Brown Rice
    Oxalate: 60
    Calcium: 1,170
    Protein: 170
    Added Sugar: 30
    Sodium: 1,560
    Calories: 1,800

    Reply
  5. Teresa

    I’m an ethical vegan with three kidney stones. I was assigned a wonderful doctor in the emergency room in Hershey, Pennsylvania (who went to U Chicago). Your article was very helpful but I’m still s bit confused about what to eat. Animal products are not an option. Any suggestions would be greatly appreciated. Thank you.

    Reply
  6. Kem

    Im have a kidneys stone, im taking medicine as pres by my Doctor, potassium citrate1200meqs 3x a day, for 3mos, but it didnt disolve the stones, my doctor tells me that maybe the stones are two hard to break. And he concluded its a calcium oxalate stones,.and now its getting bigger from .40 CM TO .5CM. I would like to ask if what diet am i going to follow? Thank u very much, godbless

    Reply
    • Fredric Coe, MD

      Hi Kem, Potassium citrate can dissolve only uric acid stones. Calcium oxalate stones will not dissolve. I suggest you might want to read a bit more about treatment. The article you are posting is the ideal diet for stones, and it is the one you want. But perhaps a larger perspective would help. Try this. Regards Fred Coe

      Reply
  7. Spyros Root

    Adding to my previous question: I worked as a health worker in disastrously poor war torn regions of Centroamerica and never saw a case of rickets despite having seen other forms of malnutrition. I would attribute this to the tortillas even though there, for the levels of poverty, they were not cooked in limewater but in wood ash lye. For whatever that be worth…

    Reply
    • Fredric Coe, MD

      Dear Spiros, The wood ash lye is potassium hydroxide, so it provides potassium and alkali, the latter would raise urine citrate and lower urine calcium losses. Maybe that is part of the answer – good for bones. Regards, Fred Coe

      Reply
  8. Spyros Root

    Dear Dr Coe and Ms Harris,

    I am greatly impressed by the thorough and dedicated job done on your site. I have roamed it and am most amazed and it is a great help. Thank you.

    I live in Mexico, on the kidney stone-endemic Yucatan Peninsula, and have had my second bout of kidney stones in 13 years. So it is not that bad, I say, but this time there were several stones—all quite small, luckily.

    Here the basic diet is corn tortillas and beans—be they black, red or white. (I guess the black ones are what you call navy beans stateside? Sounds like they are a problem as to oxalate intake…)

    I see on your site references to corn meal and corn flour: I am not sure that the dough used for corn tortillas is either of these??

    The corn in the homemade tortillas I eat (not the commercial ones) is cooked in limewater which increases calcium by 750% making it 85 % available for absorption, then my question is: does that calcium off-set the oaxalate intake of corn enough to eat the tortillas peacefully and pleasurably?

    Thank you for your answer and wonderful job.

    Spyros

    Reply
    • Fredric Coe, MD

      Hi Spyros, It may indeed. Given several stones I would invest in 24 hour urine testing while eating as you do and thereby find out about the urine oxalate and calcium and other stone risks. Easier to measure than guess. Regards, Fred Coe

      Reply
  9. Sondra

    Diagnosed with extremely low ViT D level. I have been prescribed 50,000 IU one tab/ week for a couple of months. Will this increase my chances of forming another calcium oxalate stone

    Reply
    • Fredric Coe, MD

      Hi Sondra, No; but your low levels need explaining. Is your diet deficient? Hypercalciuria can lower vitamin D stores, is your urine calcium level high? Regards, Fred Coe

      Reply

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