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!

99 Responses to “THE KIDNEY STONE DIET”

  1. Mark

    I’ve had kidney stones 15 times. I’ve had litotripsy at least a dozen times and have had two stents. I’ve been told my stones are calcium oxalate. I’m 54 yrs old and overweight and have loss 30 lbs on a low carb diet and now feel I’m having another attack. Last summer I tried the same diet and when I got to the same amount of weight loss I developed a 10mm stone. The diet takes off the pounds so fast for me because I’m very active at work but the kidney stones are pushing me over the edge. I’ve been getting them since I was 17 and I use to blame it on dehydration because of my job but now I don’t know what to think. I’ll take any help I can get. Kidney stones have cost me a small fortune and so much pain. Thank you for any advise.

    Reply
  2. Delores Teller

    I am 66 and have had at least 10 stone episodes over past 10 years. No family history’, rest of health excellent. I have tried dietary and drink water all day long. I believe their is a link to allostatic load from high stress hormones from my work as a therapist. Think it’s related to listening to and managing trauma and cortisol dis ease

    Reply
    • Fredric Coe, MD

      Hi Delores, Stress may well matter but the proximate cause of crystals can only be supersaturations, and they can only arise from chemical alterations in urine. So a complete evaluation of blood and urine is the only way I know of to understand why stones form. Here is a nice plan for such work. Treatment without evaluation can lead to bad outcomes. Assuming diet is your main firsts step the article is a good guide. But your work and stress may indeed matter as they alter diet and fluid use. Regards, Fred Coe

      Reply
  3. Elizabeth Cornell

    According to Michael Greger, MD, Interventional studies support the population data that animal protein consumption appears to markedly increase the risk of kidney stones.

    Reply
  4. Dana

    After being in the hospital for a week following my urteroscopy I am trying to put together my kidney stone diet. I have not gotten my results back for what time of stone it is however the last stone I got tested was a Calcium Stone. I am having little to no meat, drinking 3-32oz bottles of water, drastically limiting my sodium intake and trying to cut out sugar. Is white Flour or starches like pasta off the table when you say no refined sugars?

    Reply
    • Fredric Coe, MD

      Hi Dana, The kidney stone diet is the ideal US diet – sodium below 2300 mg/day, calcium above 1000 mg/day, refined sugar (table sugar) less than 10% of calories, protein intake 0.8 to 1 gm/kg/day (not low actually). As for grains and starches they contain glucose that is released slowly with eating so they have no stone related problems. Refined sugar – cookies, cakes, pies, icecream etc – contain dextrose – glucose + fructose, and the fructose is a specific toxin with a lot of serious medical consequences we now know about. Be sure you have 24 hour urine and blood testing to exclude any special causes of stones, and followup 24 hour urine and bloods to be sure your diet treatment worked. Regards, Fred Coe

      Reply
  5. K Hunt

    I recently was diagnosed with two stones, approx. 2mm. I have very much overindulged in chocolate, sugar, colas, and nuts all of my life, especially the last year. Following this diagnosis, I am focusing on changing my diet. The pain is a good motivator. You recommend a high calcium diet. However, can that amount of calcium cause constipation? Also, I’ve read that several journal articles showed calcium SUPPLEMENTS can cause stones. Any thoughts?

    Reply
    • Fredric Coe, MD

      Hi K Hunt, Taken as food, the calcium will be less of a GI problem. Supplements are usually unnecessary. If they are, they need to be taken with the main meals, to avoid spikes of urine calcium that might indeed foment stones. The kidney stone diet is one thing – not its parts. If you do all of it you are eating as is recommended for the US population at large, so it will tend to reduce stones, bone disease, and high blood pressure. Regards, Fred Coe

      Reply

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