Oxalate
<p>Many metal ions form insoluble precipitates with oxalate, a prominent example being<a href="http://en.wikipedia.org/wiki/Calcium_oxalate" title="Calcium oxalate" >calcium oxalate</a>, the primary constituent of the most common kind of <a href="http://en.wikipedia.org/wiki/Kidney_stone" title="Kidney stone" >kidney stones</a>.</p>
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Oxalate occurs in many plants, where it is synthesized via the incomplete <a href="http://en.wikipedia.org/wiki/Oxidation" title="Oxidation" class="mw-redirect" >oxidation</a> of <a href="http://en.wikipedia.org/wiki/Carbohydrate" title="Carbohydrate" >carbohydrates</a>.</p>
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Oxalate-rich plants include <a href="http://en.wikipedia.org/wiki/Chenopodium_album" title="Chenopodium album" >fat hen</a> ("lamb's quarters"), <a href="http://en.wikipedia.org/wiki/Sorrel" title="Sorrel" >sorrel</a>, and several <i><a href="http://en.wikipedia.org/wiki/Oxalis" title="Oxalis" >Oxalis</a></i> species. The root and/or leaves of <a href="http://en.wikipedia.org/wiki/Rhubarb" title="Rhubarb" >rhubarb</a> and<a href="http://en.wikipedia.org/wiki/Buckwheat" title="Buckwheat" >buckwheat</a> are high in oxalic acid.<sup id="cite_ref-heathcock_6-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Oxalate#cite_note-heathcock-6" >[7]</a></sup> </p>
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Other edible plants that contain significant concentrations of oxalate include—in decreasing order—star fruit (<a href="http://en.wikipedia.org/wiki/Carambola" title="Carambola" >carambola</a>), <a href="http://en.wikipedia.org/wiki/Black_pepper" title="Black pepper" >black pepper</a>, <a href="http://en.wikipedia.org/wiki/Parsley" title="Parsley" >parsley</a>, <a href="http://en.wikipedia.org/wiki/Poppy" title="Poppy" >poppy</a> seed, <a href="http://en.wikipedia.org/wiki/Amaranth" title="Amaranth" >amaranth</a>, <a href="http://en.wikipedia.org/wiki/Spinach" title="Spinach" >spinach</a>, <a href="http://en.wikipedia.org/wiki/Chard" title="Chard" >chard</a>, <a href="http://en.wikipedia.org/wiki/Beet" title="Beet" >beets</a>, <a href="http://en.wikipedia.org/wiki/Cocoa_solids" title="Cocoa solids" >cocoa</a>, <a href="http://en.wikipedia.org/wiki/Chocolate" title="Chocolate" >chocolate</a>, most <a href="http://en.wikipedia.org/wiki/Nut_(fruit)" title="Nut (fruit)" >nuts</a>, most<a href="http://en.wikipedia.org/wiki/Berry" title="Berry" >berries</a>, <a href="http://en.wikipedia.org/wiki/Caryota" title="Caryota" >fishtail palms</a>, New Zealand spinach (<a href="http://en.wikipedia.org/wiki/Tetragonia_tetragonioides" title="Tetragonia tetragonioides" >Tetragonia tetragonioides</a>) and <a href="http://en.wikipedia.org/wiki/Bean" title="Bean" >beans</a>.<sup class="Template-Fact" >[<i><a href="http://en.wikipedia.org/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed" >citation needed</a></i>]</sup> </p>
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Leaves of the <a href="http://en.wikipedia.org/wiki/Tea" title="Tea" >tea</a> plant (<i><a href="http://en.wikipedia.org/wiki/Camellia_sinensis" title="Camellia sinensis" >Camellia sinensis</a></i>) contain among the greatest measured concentrations of oxalic acid relative to other plants. However the infusion beverage typically contains only low to moderate amounts of oxalic acid per serving, due to the small mass of leaves used for brewing.</p>
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Although unusual, consumption of oxalates (for example, the grazing of animals on oxalate-containing plants such as <a href="http://en.wikipedia.org/wiki/Greasewood" title="Greasewood" >greasewood</a> or human consumption of <a href="http://en.wikipedia.org/wiki/Wood_Sorrel" title="Wood Sorrel" class="mw-redirect" >sorrel</a>) may result in <a href="http://en.wikipedia.org/wiki/Kidney_disease" title="Kidney disease" class="mw-redirect" >kidney disease</a> or even <a href="http://en.wikipedia.org/wiki/Death" title="Death" >death</a> due to oxalate poisoning. </p>
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The presence of <i ><a href="http://en.wikipedia.org/wiki/Oxalobacter_formigenes" title="Oxalobacter formigenes" >Oxalobacter formigenes</a></i> in the <a href="http://en.wikipedia.org/wiki/Gut_flora" title="Gut flora" >gut flora</a> can prevent this. Cadmium catalyzes the transformation of vitamin C into oxalic acid and can result from smoking heavily, ingesting produce tainted with Cd or from industrial exposure to Cd.</p>
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