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!

335 Responses to “THE KIDNEY STONE DIET”

  1. Robert

    Hi,

    I was wondering if you could “refine” the definition of refined sugars. Do sweeteners like natural maple syrup, honey and raw sugar (the brown crystals) constitute refined sugars that should be avoided?

    Thanks,

    Robert

    Reply
    • Fredric L Coe

      Hi Robert, I can. Table sugar is a dimer of glucose + fructose. The fructose is unhealthy. Starches are just glucose – fattening but not especially unhealthy. Honey, maple syrup, all these are like table sugar – which is simply an extract from sugar plants. Fruits are full of fructose but in such small concentrations you cannot get too much eating them. But juices can concentrate a lot of fructose so you are better off dropping them. The big menace is just sugar itself, the dimer, white and deadly. Regards, Fred Coe

      Reply
  2. Allan

    Hi, in January 2019 I was diagnosed with type 2 diabetes. At the time., CT scans showed clusters of stones in both kidneys. I was 273 pounds, with a blood sugar reading of 43.6 my old. Today through the help of diet and exercise, I am 170 pounds with an average of 5.3mmol, and an A1C of 4.6 I was admitted recently to the hospital in severe pain and scans showed I had 9 stones in the tracts, I had 2 double j stents put in and was diagnosed with Nephrocalcinosis. The doctor wants me to give up meat, and watch my oxalates.. When looking over the foods that are high in oxalates, it removes a lot of the healthy foods (whole grains, spinach, almonds, beans…) that were the basis of my diabetic diet. Is there a common ground? Giving up meat is not really an issue, but giving up all the healthy carbs (whole grain, quinoa, lentils) are more of an issue.

    Reply
    • Fredric L Coe

      Hi Allen, As you might note the kidney stone diet does not make much of oxalate, it rather focuses on lower diet sodium, higher diet calcium and reduction of diet sugars. A persistent emphasis on oxalate is a holdover from prior years. Take a careful look at the diet and judge for yourself. Also, you must have serum and 24 hour urine testing to determine what is causing stones, and analysis of any stones removed – even crystals will do. Given diabetes uric acid stones are common, and your physician can determine the radiographic density of the stones – UA has a low HU value in the 300 range, calcium stones are usually over 1000. So your diabetic diet can probably stay in place – low sodium and high calcium intake are part of all healthy diets, and so is low refined sugar. Regards, Fred Coe

      Reply
  3. Molly

    Dr. Coe – in regards to calcium that is excreted in urine (during a 24 hr urine collection) – where is that calcium coming from? our bones? I do take calcium supplements (600mg – twice daily and with food), and have over 200 mg of calcium showing in my urine. Reading many of your articles, I understand that elevated sodium causes calcium loss in the urine, but again, just curious as to where this calcium is being pulled from. Thank you in advance for your time and answer.

    Thanks,
    Molly

    Reply
    • Fredric L Coe

      Hi Molly, What a fine question, and so well stated! The urine calcium comes from diet when diet is high in calcium and low in sodium, but the higher the sodium the higher the fraction of urine calcium that can come from bone. If you are a stone former, you may have idiopathic hypercalciuria, and if so a higher than usual fraction of urine calcium will be from bone. Best, Fred

      Reply
      • Molly

        Thank you Dr. Coe. I am a stone former, calcium-oxalate. I read another one of your articles where you state that it is possible to keep oxalate levels low, with high calcium intake (upwards of 4000 mg/day). Since I take my calcium with food (to bind the oxalate), is it better to take calcium carbonate or calcium citrate? (If both types of calcium work in the same manner, then I’d rather take 2 pills of carbonate VS 4 pills of citrate at each meal.) My recent Litholink lab showed my oxalates at 79 (and that is with me following a low oxalate diet, and previous value was 114), so the recommendation is to take 1 g calcium with each meal. My urine citrate is 49, so I am taking potassium citrate, 20 mEq-2x daily to help raise it. Thank you again for your thoughts.

        -Molly

        Reply
        • Fredric L Coe

          Hi Molly, You appear like people with bowel disease = so low a citrate, so high an oxalate. Calcium carbonate is fine but you need to time it with the meals. The alkali should raise your citrate. But are your physician sure why your urine oxalate is so high, citrate so low? Is it bowel disease? Regards, Fred Coe

          Reply
  4. Colette Sanneman

    Dr. Coe,
    I was a patient of yours in 2010 following a diagnosis and surgery for hyperparathyroidism. After your review of my CTs, bloodwork and two 24 hour urine collections, I followed your recommendations for lowering my sodium intake and increasing my water intake before bedtime, as stone formation typically occurs overnight. I have faithfully followed your advice but unfortunately, have just passed two small kidney stones in the past 6 weeks. My internist suggested I have a scan of my 3 remaining parathyroid glands, as I could still have a parathyroid issue without elevated serum calcium. What do you recommend?

    Reply
  5. Bianca

    Hello! How informative. I have just passed a small stone and a 2mm is sitting in the top lobe of my kidney – is there a cookbook type with details of the diet? Something very specific?

    Reply
    • jharris

      Hi Bianca,
      What we do have is an online course helping patients implement the diet. It has been very helpful for kidney stone patients: kidneystonediet.com
      Best, Jill

      Reply
  6. Lars Skugstad

    Hello, I’m on a low oxalate diet and take Potassium Citrate and Hydrochlorothiazide daily to prevent kidney stone formation. I recently starting taking taking Tumeric/Curcumin supplements to help my knee/joint inflammation, but noticed in a search online that Tumeric has high levels of oxalate and may be detrimental to reducing stone formation. What is your recommendation regarding Tumeric/Curcumin supplements? Thanks, Lars

    Reply
    • Fredric L Coe

      Hi Lars. I would suggest measuring 24 hour urine oxalate before and during use of the supplement. That is the only way to know, the rest is conjecture. If you added the normal diet calcium of 1000 – 1200 mg/d and normal diet sodium of below 100 mEq (below 2300 mg) – justified in the article you are posting on – , urine oxalate would not rise as much from food. Regards, Fred Coe

      Reply
  7. Janice

    Hello, I’m thrilled just to read what I’ve read here. Even though I’m a nurse, I did not know how important taking calcium is in my diet. My first stone was passed at age 28. The stone was found to be calcium oxilate, so as you mentioned, I thought less calcium was really better in my case. The urologist gave me a diet restricting oxilates. I kept passing stones. Stopped drinking sodas, switched to water. I tried another urologist; he basically dismissed me, said there was no need to keep bringing in the stones when I’d pass one, we knew it was calcium oxilate. Discouraged, I tried urologist #3 who, after I passed a 6.9mm stone put me on thiazide. My b/p has always been on the low side, and the thiazide bottomed me out at 90/50 ish. Not only was I prone to fainting, I was having leg cramps. So I quit taking the thiazide and quit going to the doctor.

    Age 51, went through normal menopause and no ERT. Also , developed type 2 diabetes controlled by metformin.

    After a particularly difficult episode with a stone, (age 56) thankfully I went to see urologist #4 at a big hospital in a big city. Within 1 month after testing (24 hr urine & IVPs) he told me my body made no citrate. Put me on potassium citrate and a low oxilate diet. He did lithotripsy on the larger stones, which didn’t break any of them up. My kidneys completely cleared out of stones (they looked like the stars in the sky on the IVP). I thank God for that man! He retired, I didn’t follow up with another dr, I thought I was cured as long as I took potassium citrate.

    I took low dose antibiotics since age 28 (coincidence?) for cystic acne until age 62 when I went on an anti inflammatory diet because my daily fbs was elevated to 140 and I did not want to get on insulin. My acne disappeared in 3 days. It was the gluten. So I totally eliminated gluten, which eliminated all acne, lost some weight (180 down to 160), lowered my fbs somewhat. A side note, I was diagnosed with leaky bowel syndrome; which did improve some by eliminating gluten.

    Now I’m 67. I’ve always drunk a lot of water. I have always taken a multivitamin w 500mg calcium, and a vitamin D daily. Last summer I cut down a bit on water, because of work we were doing in Mex and lack of restrooms. I also stopped eating supper, just ate once daily. I thought since I wasn’t eating supper I only needed postassium citrate for the noon meal.

    A couple weeks ago, I passed a stone, about 4mm. I was surprised; my primary doc did an mri of my kidneys, they found multiple stones both sides, and one is 8mm. I was referred to a urologist who said the former urologist did the right thing putting me on potassium citrate. I’m scheduled for lithotripsy next week. I got results of my first bone density (gyn) and it shows I have osteopenia T score is -1 left femur neck. After reading your article, I realize my usual diet has been high protein (avoid hunger) and too much salt, too many carbs that turn into sugar. Not enough fruit, I do love veggies and eat salads daily, but I try to snack at supper so I won’t gain more weight. I will talk to the new urologist about my diet, and the osteopenia. I’m just nervous about the lithotripsy and upset over the osteopenia. I thought I was doing a pretty good job eating meat for the calcium, curbing my appetite, and taking the multivitamin w some calcium & extra D. I’ve been washing all the calcium out with salt and carbs. I don’t even smoke, so I thought I was at low risk for bone problems as I get older, and never even asked about having a bone density.

    Is there anything else I should ask about? Not sure on which calcium is best absorbed, but I will be changing my diet today and ordering some calcium to take with meals. Thank you so much for getting this info in our hands. You will make a big difference in many lives.

    Reply
    • Fredric L Coe

      Hi Janice, The diet calcium protects your bones and also blocks oxalate absorption but high diet calcium will raise urine calcium unless diet sodium is reduced to below 2000 mg and often one needs to go even lower, to 1500 mg/d. Also, the calcium is useless for oxalate blockade unless taken with meals that have oxalate in them, and it is probable that it is best taken with nutrients so bone will best use it. These principles led me to develop the kidney stone diet out of the research we had available. Here is a good review of the science and the diet. Regards, Fred

      Reply
  8. Jason

    Thanks Jill 🙂
    Has anybody asked about plant sterols (for heart health)?
    I know that the majority of the “sterols” come from soy, but because it’s processed, would this lessen the oxalate?

    Reply
    • Fredric L Coe

      Hi Jason, a PubMed search for oxalate in soy sterols revealed no papers. Likewise a search for oxalate in heart healthy diets. This rather old article appears to be a major one on the soy oxalate topic, but not concern heart disease prevention nor sterol extracts. The bests approach is to measure 24 hour urine oxalate on the diet needed and see if it is above the risk threshold. Regards, Fred Coe

      Reply
  9. Jason

    Hi I might have asked this before, but I am unsure. Is psyllium husks high in oxalate? I need extra fiber in my diet and I have been taking it for quite awhile. I was pretty sure I read somewhere it was low oxalate, but cannot find the source anymore. Was it ever tested?

    Reply
    • jharris

      Hi Jason,
      You have and I replied saying it was fine. I love getting enough fruits and veggies to help with my fiber intake but if you just cant get to the recommended 30grams per day it is safe to bump it up with psyllium husk.
      Best, Jill

      Reply
  10. Janet

    I had my first kidney stone 25 years ago and several more oxalate stones in the next few years. Within the past 15 years or so, I’ve had a only few small stones. But, 8 years ago, at the age of 51 I was diagnosed with osteoporosis caused by hypercalciuria. I was put on a thiazide which seemed to fix the urine calcium problem. Very recently, I repeated the 24 hour urine test and the result was 420 mg of urine calcium even though I took my thiazide during the collection period and consumed about the same dietary calcium I have been all along. All other tests were normal, just as they were 8 years ago. I have not taken any medication for the osteoporosis but I have pretty much maintained my bone density levels over the past 8 years.
    In reading all the valuable information on your site, I believe that I should start following your recommendations for the kidney stone diet. I’m assuming the same diet would help to preserve my bone density. My question is whether or not it would be appropriate for me given that I’m producing very few stones these days?
    Thank You

    Reply
    • Fredric L Coe

      Hi Janet, The kidney stone diet, as it happens, mimics the US ideal diet, so we all should be eating it! One key for you may be diet sodium. If not low enough, thiazide will not work well. So, of course use the diet. As for the bone disease, if BMD is stable, perhaps things are reasonable as is, but I am sure your physicians will want to keep a close watch and if needed add bone active meds. One issue with hypercalciuric bone disease is that bone density does not closely predict fragility and fracture. That is merely an observation we have made, and not published. Perhaps a low sodium diet is of real importance for you – 24 hour testing is crucial, no one can tell how much sodium is being eaten. Regards, Fred Coe

      Reply

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