Holmes R P, Kennedy M
Department of Urology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Kidney Int. 2000 Apr;57(4):1662-7. doi: 10.1046/j.1523-1755.2000.00010.x.
The amount of oxalate ingested may be an important risk factor in the development of idiopathic calcium oxalate nephrolithiasis. Reliable food tables listing the oxalate content of foods are currently not available. The aim of this research was to develop an accurate and reliable method to measure the food content of oxalate.
Capillary electrophoresis (CE) and ion chromatography (IC) were compared as direct techniques for the estimation of the oxalate content of foods. Foods were thoroughly homogenized in acid, heat extracted, and clarified by centrifugation and filtration before dilution in water for analysis. Five individuals consuming self-selected diets maintained food records for three days to determine their mean daily oxalate intakes.
Both techniques were capable of adequately measuring the oxalate in foods with a significant oxalate content. With foods of very low oxalate content (<1.8 mg/100 g), IC was more reliable than CE. The mean daily intake of oxalate by the five individuals tested was 152 +/- 83 mg, ranging from 44 to 352 mg/day.
CE appears to be the method of choice over IC for estimating the oxalate content of foods with a medium (>10 mg/100 g) to high oxalate content due to a faster analysis time and lower running costs, whereas IC may be better suited for the analysis of foods with a low oxalate content. Accurate estimates of the oxalate content of foods should permit the role of dietary oxalate in urinary oxalate excretion and stone formation to be clarified. Other factors, apart from the amount of oxalate ingested, appear to exert a major influence over the amount of oxalate excreted in the urine.
草酸的摄入量可能是特发性草酸钙肾结石发病的一个重要风险因素。目前尚无列出食物草酸含量的可靠食物表。本研究的目的是开发一种准确可靠的方法来测量食物中的草酸含量。
比较了毛细管电泳（CE）和离子色谱（IC）作为估算食物草酸含量的直接技术。将食物在酸中充分匀浆，加热提取，经离心和过滤澄清后，再用水稀释进行分析。五名食用自选饮食的个体记录了三天的食物摄入情况，以确定他们的平均每日草酸摄入量。
两种技术都能够充分测量草酸含量较高的食物中的草酸。对于草酸含量极低（<1.8毫克/100克）的食物，离子色谱比毛细管电泳更可靠。接受测试的五名个体的平均每日草酸摄入量为152±83毫克，范围为44至352毫克/天。
由于分析时间更快且运行成本更低，在估算草酸含量中等（>10毫克/100克）至高的食物中的草酸含量时，毛细管电泳似乎是比离子色谱更好的选择，而离子色谱可能更适合分析草酸含量低的食物。准确估算食物中的草酸含量应有助于阐明饮食草酸在尿草酸排泄和结石形成中的作用。除了草酸摄入量外，其他因素似乎对尿中草酸排泄量也有重大影响。
