Causes of Kidney Stones

What causes kidney stones?  It was once thought dietary calcium was a major cause of kidney stones.  To prevent kidney stones patients were once advised by their doctors to limit dietary calcium.  Convincing research has proven the opposite is in fact true.  Normal dietary calcium intake, along with reduced salt and protein, is now advised for preventing kidney stones.¹

Based on the best information they had 15 years ago, doctors used to prescribe a low calcium diet for preventing kidney stones.  This approach makes little sense if you understand how calcium is managed in the body.  Calcium levels in the blood are kept steady by balancing the absorption of calcium from your diet and taking calcium from your bones when needed.  Changing the amount of calcium in your diet causes very little change in the blood level of calcium.  The kidney filters substances from the blood, so changing the dietary intake of calcium does not change the amount of calcium that is filtered by the kidneys. 

Kidney Stone Prevention

Therapy aimed at decreasing and preventing kidney stones, is now recommending a high calcium diet.  Calcium restriction in stone formers is not recommended because it can have adverse effects on bone and the incidence of stones.²

The recommended daily intake of calcium for adults is 1000 mg per day, but research shows the average American adult is getting 600 mg of calcium daily from their food.^3-4  Any nutritionist, doctor or text suggesting calcium reduction is in serious error.  It has been strongly suggested in recent scientific literature that low calcium may be a cause of kidney stones.⁵

There are some unscrupulous calcium suppliers that claim any calcium supplement which is not completely absorbed contributes to kidney stones - and of course, they are offering a "high absorption" calcium product.  The truth is that unabsorbed calcium binds to oxalate from digested food in the intestine and decreases the elimination of oxalate in the urine, which is how kidney stones form. 

To prevent kidney stones it is recommended to follow a calcium rich diet and avoid oxalates.  If calcium is present in the diet with oxalate, then calcium and oxalate bind in the intestine.  This way, less calcium and oxalate enter the blood so that oxalates are not available to bind with calcium in the kidney.

If you are not maintaining the recommended calcium in your diet you may need calcium supplementation.  To learn more about AlgaeCal calcium supplement please click here

References

1. Hall PM. Related Articles, Links Preventing kidney stones: calcium restriction not warranted. Cleve Clin J Med. 2002 Nov;69(11):885-8

2. Martini LA, Wood RJ. Related Articles, Links Should dietary calcium and protein be restricted in patients with nephrolithiasis? Nutr Rev. 2000 Apr;58(4):111-7

3. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington DC: The National Academies Press,1997.

4. US Department of Agriculture, Continuing Survey of Food Intakes of Individuals, 1994-96

5. L. H. Smith, et al, "Medical Evaluation of Urolithiasis" Urological Clinics of North America 1:2, 241-260, June 1974

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