Kidney Stones and Calcium
Are high-calcium diets related to the formation of kidney stones? No. People who suffer from kidney stones don’t need to eliminate milk products from their diet.
In fact, recent research indicates a beneficial effect of milk product consumption in preventing the formation of some types of kidney stones.1-5
In the past, people who experienced kidney stones were advised to reduce their intake of calcium-rich foods such as milk and cheese. This is likely due to some types of renal stones containing calcium and a high concentration of calcium in urine (hypercalciuria) is often observed in patients who suffer from kidney stones.6 A low-calcium diet, however, does not appear to decrease urinary calcium in this population.7 Research has also demonstrated that drinking milk may actually be a good strategy for preventing the formation of kidney stones.1-4 Calcium supplements do not appear to have the same protective effect and may actually increase the risk of stone formation; thus, calcium from dietary sources is recommended.2
Many people form kidney stones from oxalate, which is found in some fruits, vegetables, legumes and grains. Most often however, oxalate stones are due to mega-dose of vitamin C supplements. One of the ways dietary calcium decreases renal stone formation is that calcium helps limit the absorption of oxalates by binding to them.5 Consuming milk between meals is also recommended because some calcium is excreted with the oxalate and it is important to get enough dietary calcium to compensate for this loss.
In summary, calcium restriction is not recommended because it can have adverse effects on bone health7,8 and can actually increase the incidence of kidney stones.3,9,10
References
- Curhan GC. Dietary calcium, dietary protein, and kidney stone formation. Miner Electrolyte Metab, 1997. 23(3-6): p. 261-4.
- Curhan GC et al. Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women. Ann Intern Med, 1997. 26(7): p. 497-504.
- Curhan GC et al. A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. N Engl J Med, 1993. 328(12): p. 833-8.
- Massey LK and Kynast-Gales SA. Substituting milk for apple juice does not increase kidney stone risk in most normocalciuric adults who form calcium oxalate stones. J Am Diet Assoc, 1998. 98(3): p. 303-8.
- Liebman M and Chai W. Effect of dietary calcium on urinary oxalate excretion after oxalate loads. Am J Clin Nutr, 1997. 65(5): p. 1453-9.
- Krause’s Food, Nutrition & Diet Therapy. 11th Edition, Saunders ed. 2004, Philadelphia: Elsevier (USA).
- Trinchieri A et al. A study of dietary calcium and other nutrients in idiopathic renal calcium stone formers with low bone mineral content. J Urol, 1998. 159(3): p. 654-7.
- Lauderdale DS et al. Bone mineral density and fracture among prevalent kidney stone cases in the Third National Health and Nutrition Examination Survey. J Bone Miner Res, 2001. 16(10): p. 1893-8.
- Martini LA and Wood RJ. Should dietary calcium and protein be restricted in patients with nephrolithiasis? Nutr Rev, 2000. 58(4): p. 111-7.
- Martini LA and Heilberg IP. Stop dietary calcium restriction in kidney stoneforming patients. Nutr Rev, 2002. 60(7 Pt 1): p. 212-4.
Keywords: kidney stones
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