There are many mechanisms by which calcium oxalate kidney stones are formed. However, the common pathway includes an increase in the blood concentration of oxalate which eventually leads to an increase in the oxalate excreted in the urine. This is caused by an increase in the intake of oxalate-containing foods, an increase in the absorption of oxalate, and an increase in the metabolic production of oxalate, which could be acquired or genetic. Finally, an increase in the conditions that can cause crystallization of calcium oxalate is also needed.
Increased Oxalate Intake.
There are certain foods that are known to have increased oxalate content. Almost all of them are of vegetable origin. In order to know which foods are the ones that contain high oxalate amounts one has to refer to known sources of information such as websites, books, or your physician. A general rule is that spinach, rhubarb, nuts, chocolate and several types of tea contain high amount of oxalates.
How much is considered a an excessive or risky amount of oxalate? If someone is a known stone former, he or she should not consume more than 100 mg of oxalate in a day. We have to keep in mind that in normal circumstances usually up to 50% of the ingested oxalate comes from diet is absorbed and usually 4-12% of ingested oxalate is absorbed.
References
Lieske, John, William J.Tremaine, ClaudioDe Simone, Helen M.O’Connor, Xujian Li, Eric J. Bergstralh, David S.Goldfarb. “Diet, but not oral probiotics, effectively reduces urinary oxalate excretion and calcium oxalate supersaturation." Kidney International 78, no. 11 (2010): 1178-1185. https://doi.org/10.1038/ki.2010.310.
Kidney Stone Patient. “Oxalate (oxalic acid) content of 750+ foods, with numbers from university and government sources.” Accessed December 25, 2019. https://oxalate.org.
Holmes, Ross P, Harold O.Goodman, Dean G.Assimos. “Contribution of dietary oxalate to urinary oxalate excretion." Kidney International 59, no. 1 (2001): 270-276. https://doi.org/10.1046/j.1523-1755.2001.00488.x.
Voss, Suzanne, Albrecht Hesse , Diana J. Zimmermann , Tilman Sauerbruch , and Gerd E. von Unruh. “Intestinal Oxalate Absorption is Higher in Idiopathic Calcium Oxalate Stone Formers Than in Healthy Controls: Measurements With the [13C2]Oxalate Absorption Test." The Journal of Urology 175, no. 5 (2006): 1711-1715. https://www.auajournals.org/doi/10.1016/S0022-5347%2805%2901001-3.
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Introduction
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© 2019 Second Medical Opinions PLC. All rights reserved
