Recently we presented what we think of as The kidney stone diet, meaning a unitary diet platform suitable for idiopathic calcium stone formers in otherwise good health. The story of that diet and the implications it has for stone prevention deserve perhaps a bit more commentary than we allowed for in the original article.
The lovely image – Hendrick van Cleef, The Building of the Tower of Babel hangs in the Kröller-Müller Museum. He (1525 – 1589) is one of a family of famous painters and
The Narrow Winding Path
Over many decades, kidney stone researchers have gradually recognized what the ideal kidney stone diet might be. They did this mostly via normal science, the experimental testing of prevailing theory.
The way it happened, how our community gradually recognised the elements of a proper stone prevention diet, helps us understand where we are at today.
Here is a brief review sans references.
Calcium and Sodium
The very common idiopathic (genetic) hypercalciuria (IH) of calcium stone formers, only slowly gave up its secrets to three generations of excellent scientists. Early on, they recognized that intestinal calcium absorption was high. This led clinicians to try the effects of low calcium diet. The results were encouraging. Urine calcium excretion fell, and so did new stone formation. IH appeared to be a state of high calcium throughput from food into urine, easily and safely treated by low calcium diet.
But the bone disease of IH gradually became apparent. IH was not just a result of over-efficient calcium absorption but also of inefficient kidney calcium conservation, so bone mineral could be lost if diet calcium were not maintained. At first it appeared that IH might be of several kinds: Due to the intestine or due to the kidneys and intestine. We now know that intestine and kidney both play a role so one cannot safely reduce diet calcium as a treatment. A single trial of low calcium vs. ‘high’ calcium diet made the point very clear: Both lowered new stones but only the ‘high’ calcium diet did so lastingly over five years.
The secret was sodium restriction. With it, kidneys conserve calcium very well even in IH, so a ‘high’ calcium diet is safe. Eventually scientific and medical opinion came to favor a ‘high’ calcium – ‘low’ sodium diet.
The quotes are because we are in a time of change. The diets of many people even today hardly match contemporary recommendations, being lower in calcium and higher in sodium, so those recommendations can be viewed as high and low, respectively, compared to what is being done.
No one ever doubted the importance of urine oxalate in calcium oxalate stone formation or the benefit of lowering diet oxalate. But one group in particular pioneered in showing high calcium intake could permit a less stringent reduction in food oxalate yet keep urine oxalate within bounds This supported the benefits of high diet calcium although it did not at all diminish the importance of care about diet oxalate. Many think reciprocity between diet calcium and urine oxalate is a reason epidemiology has linked higher calcium intakes to a lower incidence of stones.
Diet protein in excess of that required for nitrogen balance raises urine calcium and decades of work concerned the mechanisms involved and whether or not high protein intake promotes bone mineral loss. This last issue remains unsettled as experts still joust with no clear winner. But the outcome for stone formers is neutral: Eating enough protein to maintain nitrogen balance is best for stone formers as for people in general.
Dr Jacob Lemann first showed the remarkable calciuric effects of simple sugars in normal people and that IH exaggerates the sugar effect. Sugars reduce kidney calcium conservation and so not only raise stone risk but could in principle deplete bone mineral. Even taken alone, his work is enough to warn stone formers with IH away from an excess of refined sugars.
The Royal Way
During our decades of labor those involved with the grand diseases of humankind were constructing their own final vision of what we should eat as a people.
To them, the need for diet calcium far in excess of normal behavior was glaring as they gazed on the massive burdens of osteoporosis.
Arguments of colossal scale and vituperation raged internationally over diet sodium as a cause of hypertension and over ‘low’ sodium vs. ‘normal’ sodium diets in treatment and prevention. Finally, much lower sodium than has been the norm won right of rule and the ponderous engines of government turned that way.
Sugar has been perhaps the last great battleground. The once ‘heart healthy’ high carbohydrate diet, tolerant of refined sugars as having little harm, has fallen into ignominy as a cause of rampant obesity and diabetes. Refined sugars now are shunned as unhealthy.
The Merging of the Choirs
And so it was as our small band fulfilled its quest for the right kidney stone diet, or, by way of metaphor, as we found the tune we wished to sing, we encountered not a passel of like sojourners but the massed choirs of the nations of the world, singing a like song in majestic chorale.
What we have called a ‘high’ calcium diet is not high now but merely proper. What we have called a ‘low’ sodium intake is not low, now, but merely proper. And sugar has become a demon in all eyes, dreadful to behold.
So, we stand among the ranks of the world’s anointed, and what we would say turns out to be what is said by all.
We Share the Kidney Stone Diet With the World
We have our kidney stone diet, which is more or less the right diet for healthy people, and it is our job to proliferate it as treatment for our patients.
The government and the societies have provided a richness of resources newly minted and our task now is to bring them into use for our patients.
Sums scarcely dreamed of in our world have been spent explicating for the American people the way to eat as we would want our patients to eat, and we need to help our patients use the resulting materials properly. Put another way, we have no reason as a community to await trials of low sodium intake, high calcium intake, low refined sugar intake, or low protein intakes: The prevailing relatively low calcium, high sodium, high sugar, and high protein diets are no longer viable alternatives for normal people and as physicians we must push against them with our kidney stone patients.
There is some exceptionalism about stone formers.
Response of IH to sodium and sugar is exaggerated, so the sodium intake of 1500 mg advised for high blood pressure may be better than the 2300 mg level advised as the upper limit for normal people. The need for enough calcium intake to prevent bone disease is perhaps more significant than in normal people because of IH.
Oxalate absorption may be abnormally high in some stone formers, which makes management of diet calcium and oxalate, and their timing with meals, unusually demanding.
Response of urine calcium to diet protein may be higher than in normals; this has not been tested well, but for the moment it means that very high protein intakes could be especially unwise.
So we need to promote the general ‘healthy people’ guidelines for treatment of our patients but with a few significant exceptions and points of special care.
Some of the Vast Resources
The FDA is the biggest. In it are massive amounts of diet information, portion sizes, meal plans, recipes, and materials for professionals. The DASH diet has long been advocated for higher calcium, lower sodium, and indirectly for less refined sugar. Being directed toward blood pressure management it has a large amount of nuts and seeds in it which may not always be ideal in relation to oxalate. The American Heart Association is another main source, albeit with a special emphasis. The American Diabetes Association can be mentioned although their site does not seem to emphasise diet calcium and sodium.
Many idiopathic calcium stone formers can and will use these resources and plan their diet calcium, sodium, protein, and sugar intakes with an understanding of the above mentioned special issues concerning stone formation.
But many will not be able to do this. It is no small matter to translate the mass of information into real change of eating habits.
Some may be enabled by sites like this one, or by handouts and perhaps books, and need nothing more.
Some may need additional education beyond what books and websites can provide.
Some may require one on one nursing or nutritional counseling to solve their specific problems.
A few will require that physicians themselves enter into the details of diet management.
How Will We Make Up the Difference?
Some physicians may use combinations of handouts with brief nursing or nutritionist time to provide basic educational support.
When one on one detailed nursing or nutritionist education is needed patients will usually have to expect additional out of pocket costs depending upon insurance carriers.
We who write this have vast experience with the problem of stone prevention, one as a physician the other during a decade of work at Litholink and years of private practice consultation. From our experience we believe a scalable approach will require that some in nursing and some nutrition practitioners take a special interest in understanding stone disease prevention and add to their professional qualifications requisite additional expertise.
Support group structures may be beneficial.
There is no longer any reason to wait concerning the right diet for kidney stone patients. We know the answer. It is time to do it.
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!