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. Irit

    In June 2019, I discovered that I form kidney stones. I moved to a PLANT BASED diet exclusively since Jan 2018.
    After some nagging pain returned to the kidneys in the fall, I took the 24Hrs urine test and was just told by my urologist that I make Calcium Oxalate stones. He wants me to increase the intake of calcium based food and off dark green leaf vegetable, nuts, legumes. So far, it is consistent with your recommendations.

    With the help of the Harvard list of Oxalate foods, I was able to identify the culprits in my diet that may have contributed to creating stones for the first time at the age of 69+.
    Unfortunately, most of the plant based foods that are rich in calcium are also rich with oxalate. I’m in search of a list that will point me to PLANT BASED food that are low in Oxalate and rich in Calcium. Thanks.

    Reply
    • Fredric L Coe

      Hi Irit, Stone prevention is not ideally done quite this way. You assume your recent diet caused the stones, and that is not a bad idea, but you may have other factors at work. I would hope you get fully evaluated for cause – here is a good article on the subject. The kidney stone diet is like a house, the various parts – low sodium, high calcium, moderated protein, avoidance of very high oxalate foods, reduced sugars complement each other and the science is good. Plants have little calcium to offer, it being bound with oxalate. There are no foods that do what you describe. One uses milk products to provide calcium or else calcium supplements. Having stones late in life is a special issue, and this article may be of use. An emphasis on oxalate is usually not enough. Regards, Fred Coe

      Reply
  2. Bill Evans

    Hello Dr. Coe:

    I was wondering if there might be a weekly or monthly meal plan – menus – that might help to avoid kidney stones. I thinking of something along the lines of a schedule for breakfast, lunch, dinner and snacks maybe that suggests in detail some menus with the best foods. I’m thinking of the kind of thing that Atkins or Nutrisystem publishes only targeted explicitly to kidney stones instead of primarily weight loss. Thank you very much.

    Reply
    • Fredric L Coe

      Hi Bill, Making up a meal plan is hard work and expensive to produce. Do you think there is a market large enough? Atkins etc do well, but are very broad in their reach. Fred

      Reply
  3. Ginger

    I have just learned I have large Ca oxalate stones in left kidney; several small ones in right kidney. I am very confused about diet discrepancies amongst what most would consider reliable sources – like Kaiser Permanente, Cleveland Clinic, NIH etc. It would be helpful if lists would include specific portions or amounts when they say things like, “eat less protein”, “watch sodium intake”, “drink citrus based drinks, but don’t overdo Vitamin C”, “eat SOME dairy with each meal”, etc. And also when such amounts are given – that it is in a format that is useful. Most product labels list nutrition in a percent of a 2,000 calorie diet. I have no way of converting that percentage into a mg amount !!! These genial statements are just not helpful at all. Given the number of people who suffer from kidney stones, I am astounded that the medical field and food industries have not addressed this issue in a helpful, meaningful way.
    So please advise for an older woman how much of these per day ( in a useful format)…???
    Sodium
    Calcium
    Vitamin C
    Protein – and is this just for meat or does it include dairy protein too?
    Amount of calcium per amount of oxalate intake / per meal
    Total oxalates / per day
    Medications that are conducive to Ca oxalate stone formation

    Thanks you!

    Reply
    • Fredric L Coe

      Hi Ginger, The kidney stone diet is more complex than it seems. Here is the science behind it. For sodium, amounts are in mg and mEq; labels are all ini mg. For calcium, the ideal diet is taken as 1200 mg/d for an adult, so fractions refer to that. You have to convert percentage into amounts because the law has not yet forced producers to list amounts directly for calcium and they prefer vagueness. For you, as a woman, 1000 – 1200 mg of calcium is an ideal for US citizens. Using calcium foods with main meals reduced oxalate absorption, giving exact amounts is futile as people cannot be so exact while living their lives. I would suggest you read through the link, and that may help clarify the strategy and the science. As for discrepancies, sites vary. This one is rather detailed because I have the time to detail it. I think the people at Kaiser, Cleveland, NIH will not disagree with me most of the time. As for being genial, I am not. Here is your list: sodium – below 2000 mg/d, calcium 1000 – 1200 mg/d, vitamin C – the amount in a once a day vitamin, protein 1 gm/kg/day (shown as PCR on routine 24 hour urine reports), oxalate 200 mg/d or less. medications causing stones – too numerous and too vague a question. Warm regards, Fred Coe

      Reply
  4. Ginger

    I am not crazy about drinking a lot of water and have been looking for other CA oxalate stone appropriate drinks. Are cider vinegar drinks appropriate? I have found a brand in glass bottles (important non-plastic issue for me) that is made with various flavors – like cherry and cinnamon.

    Reply
    • Fredric L Coe

      Hi Ginger, I see no special issues with cider unless it contains a lot of sugar. Regards, Fred Coe

      Reply
  5. Jon Tilton

    I have had both Uric Acid and Oxalate stones, is there a comprehensive diet that easily prevents stone formation. Items on one diet that are verbotten are okay on another diet. At 72 years of age with co-morbidities of HTN, BPH, Type 2 diabetes and CLL it is very frustrating to follow a simple path.

    Reply
    • Fredric L Coe

      Hi Jon, Uric acid stones are not treated with diet but rather with alkali to raise urine pH above 6. Diabetes is a common cause of low urine pH and uric acid stones. Given the multiple additional diseases, I am sure your physicians will want to do 24 hour and serum testing appropriate for stone prevention. The uric acid component is – as I said – preventable with potassium citrate or – if potassium is not advisable for you – a sodium citrate or bicarbonate salt. The calcium component may have causes apparent on serum and 24 hour urine testing. The kidney stone diet is not itself organized for uric acid stones. Regards, Fred Coe

      Reply
  6. Guissou Sharifi

    My kidneys used to make urate stones. I am a hyperuricemia one that in a bad condition with memory loss. So I need to get more meat and fish and walnuts to touch borderline for good myelination my nerves and preventing AD. Today the lab report said both kidneys have stones about 3mm and one had hydronephrosis. What do you recommend to me?
    @diet_therapy_guissou_sharifi my address on Instagram.

    Reply
    • Fredric L Coe

      Hi Guissou, Given uric acid stones, the best treatment is to raise the pH of the urine with potassium citrate. In fact, it is the only reasonable treatment. One thing, though, you say urate stones, not uric acid stones. Urate stones must be with a counter ion – potassium urate, sodium urate, ammonium urate, and if you have been making one of more of these urate stones then treatment is far more complex. Your physician will know, and also knows that uric acid stones are easily prevented with potassium citrate. Ask him/her, and of course your physician is entirely responsible for your care. Never try to prevent stones without a physician supervision. Regards, Fred Coe

      Reply
  7. Sandra Bradsky

    Hi,
    I just found out I have calcium phosphate kidney stones and wondering what kind of diet I should follow?
    Thanks,
    Sandra

    Reply
  8. Randy Jones

    I was eating a very high oxalate diet and suffered from kidney stones. I am now very careful in what I eat. What confuses me is why am I seeing sardines on the list of high oxalate foods to avoid? I am guessing they are high in purines and should be avoided for people with certain stones but mine were calcium oxalate stones. I love sardines and they are a staple in my diet post kidney stones. I would think even if they have oxalates they are so high in calcium with the bones in them it would not be an issue anyway. Can you explain this?

    Reply
    • jharris

      Hi Randy,
      They have no oxalate as plant food only contains oxalate. They are very high in sodium.
      Best, Jill

      Reply
      • Randy Jones

        That is what I thought but it is listed on many lists as moderate levels. One showed them as 4 oxalates per 100 grams. Very confusing looking at all these lists!

        Reply
      • Randy Jones

        One list showed them as 4 oxalates per 100 grams. Very confusing!

        Reply
  9. Natalie Luna

    Hello Dr. Coe,

    I went to the doctor today and I’ve lost 3 more pounds since this began. Which isn’t good news for me. I’m down to 115 from 123. I’m sure some of it is from only drinking water these last few weeks and cutting out soda. But how can I stabilize and gain my weight back or at least, 5 pounds? I know I can’t drink Ensure anymore so I’m at a loss. Thank you for all you do.

    Reply
    • Fredric L Coe

      Hi Natalie, The kidney stone diet matches the US ideal diet, so your weight should stabilize if you have no underlying disease. But I do not know your medical condition, so you should discuss this with your personal physician who can help you decide if this is a normal loss of excess weight or a problem. I am too far from your real life to make any serious medical comment. Regards, Fred Coe

      Reply
  10. Judith

    When I do the formula for .8 to 1 gram protein per kg per day, I get only 2 to 3 ounces as my daily allowance (144 lb=65kg, 65g/28g = 2+ oz per day). How did you come up with 1/2 to 2/3 pound?

    Reply
    • Fredric L Coe

      Thanks, Judith, a very reasonable question. It is indeed 2.29 ounces of protein for you. There are about 7 gm of protein in one ounce of cooked meat – like chicken, so for your 65 gm of protein you would need 9.28 ounces of cooked meat, and given 16 ounces per pound that comes to 0.58 pound – or just under 6/10 pound cooked a day. Regards, Fred

      Reply

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