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. Rob

    I had a few stones in 2017. Been free since. I am now starting intermittant fasting and read it can cause stones.
    Is that true and how? If I drink my 3 litres of water daily and don’t eat oxalates how will it create stones?
    thank you you were so helpful when I had the stones AND DO NOT WANT THEM AGAIN!

    Reply
    • Fredric L Coe, MD

      Hi Rob, It will be alright if you drink a lot and avoid oxalates. But be sure the lot is 3 liters/d of fluids at least. Fred

      Reply
  2. RCB

    This article is great and exactly what I’ve been looking for in terms of all items in one place! I have Crohn’s Disease and follow the Specific Carbohydrate Diet (SCD) as well. For about a year, I’ve been looking to find a sweet spot of foods/amounts of food that fit between the 2. One question that i have regarding increased calcium intake along side of high oxalate foods. Is any ratio of calcium:oxalate that should be considered? Also, when making nut based bread, is their any value in adding calcium to the recipe? I have calcium citrate capsules (200mg) and was wondering if adding some of that to a recipe would have any benefit. Thanks and have a great day.

    Reply
    • Fredric L Coe, MD

      Hi RCB, No ratio. The diet calcium is best from food and should be present with meals apt to contain oxalate. Adding calcium to foods is fine, as it is an atom and therefore immortal. The idea of adding calcium to nut bread – high oxalate potential – is ingenious! Very original. Does it taste good? Regards, Fred Coe

      Reply
  3. Rae K

    I am confused about soy products. I do not eat meat (other than fish and sardines for calcium) but I do eat tofu for protein. I have soy milk a few times a week with cereal. I am wondering if in Asia where tofu, soybean pastes, sprouts are eaten daily and even several times daily, whether there is a high incidence of kidney stones? They also traditionally do not use dairy products and thus don’t get calcium from dairy. Thanks!

    Reply
    • jharris

      Hi Rae,
      Barley flour is more concentrated so will be higher in oxalate. You can have your barley, potion not perfection applies here and make sure to get your daily recommended amount of calcium.
      Best, Jill

      Reply
      • Rae

        ? Not sure about your response: I didn’t mention barley, just soy. Maybe you were answering another person’s question?

        Reply
        • jharris

          Hi (again) Rae,
          Sorry, must have answered the wrong question. Soy can be higher in oxalate. Find another non dairy milk like pea or flax unsweetened that you switch to so that you get your calcium needs met. Can you eat other non soy foods for your protein?
          Best, Jill

          Reply
  4. Will Kuhlman

    What is your thinking re vitamin/mineral supplements and pharmaceuticals as contributing factors in someone who has formed calcium oxalate stones?

    In particular, is there good clinical evidence that the use the of magnesium glycinate or the drug gabapentin should be avoided?

    Reply
    • Fredric L Coe, MD

      Hi Will, apart from excess vitamin C, I know of no special hazards. The two agents you mention are not known – to me – as causes of stones. Regards, Fred Coe

      Reply
      • Will Kuhlman

        Thank you for your response and for the wealth of information you’re providing on this site!

        Will

        Reply
  5. Mary Torti

    Hi Dr. Cole, I am really very naive when it come to this topic. I have presently having an issue that is making me feel I have kidney stone. Sometime last year I had lots of acid in my tommy and back pain. I went to the doctor and she had me checked and said I was ok. She did a scan and discovered my neck didn’t look alright and sent me for mri scan. After I did the scan she sent me to see a neurologist because I had some dislocated disc neck, middle and lower back. The neurologist sent me to physical therapy which I did for months and felt better. Fast forward to this year, sick with pain in my stomach, and a pain that seemed to radiate from my back, sides and circles around my stomach. Someone recommended I should see a gastroenterologist and after explaining he said it was acid reflux, gave me medications which didn’t help. Went back after some days explained that the pain seems to come from my back to my waist and sides and he said some stomach pain comes from the back he said I needed colonoscopy and endoscopy which I did February 2020 and the analysis showed I had erosive gastritis and unspecified colitis. I have been taking medications like food for months but the back and sides pain remain. But i noticed i always had pain below my tummy every morning which seems to relieve once I peed.one night in March after riding my bike I came back home went to the use the restroom, came out and immediately felt an urge to pee again and it was weird because I felt so strange in my and around my waist. I had just a drop and seconds later I went back and peed blood, very nervous with the experience I rush to hospital and after hours of waiting I was finally attended to and from the pee analysis they told me it was chronic uti gave me some iv and antibiotics which I took for 10days but instead of getting better the sides pain increased. I did a culture pee test but before test had Ciproflox DM 5 and after pee test showed bacteria resistant to Ciproflox doctor recommended another and although the pain dialed down a bit but the sides pain subsided and the came back couple days later. Went to see another doctor who asked for pee culture and gave me gentamicin injection 5 days which will end today 13/5/20. I am really stressed out and frustrated and I want to know does it take this long to treat UTI or is this a kidney stone. By the way I live in Mexico I do not know how to read the test because everything is in Spanish but it keeps mentioning staphylococcus. Please help, I am sorry my comment is too long

    Reply
  6. Jeff

    I had a 45 mm calcium stone that was removed in pieces through my back in 2017 and a 14 mm stone that was blasted by lithotropsy last year. The whole thing about how much calcium and how much sodium is confusing. After all, they’re calcium stones and I raise my calcium intake? And sodium seems to be nearly impossible to avoid.

    Reply
  7. Robert

    I apologize for posting the same questions twice. I did not notice the
    “being moderated” when I posted the first time and thought I had made a mistake. Feel free to keep the version you prefer. If possible, I would appreciate it if you do not use my last name when you respond.
    Robert

    Reply
    • Fredric L Coe

      Oh! I found this after the other two. Too late! Sorry. Fred

      Reply
  8. Robert Boire

    Hi,

    Thanks for the wealth of information. I have “elevated” pressure and am an occasional stone former. The last one was a year ago and before that about 8 years ago.

    I was hoping that you could “refine” the definition of refined sugar. In particular I was wondering if products like natural maple syrup, honey and “raw” sugar (the brown crystals) are considered to be refined sugars or if they could be considered as refined sugar substitutes.

    Robert

    Reply
    • Fredric L Coe

      Hi Robert, I believe I answered part of this, here is the rest. Brown sugar is the same dimer of glucose and fructose as white sugar. Honey is filled with fructose and maple syrup is 67% sugar. No hope. Fred

      Reply

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