Kaup S M, Greger J L
Department of Nutritional Sciences, University of Wisconsin, Madison, WI 53706, USA.
J Nutr Biochem. 1990 Oct;1(10):542-8. doi: 10.1016/0955-2863(90)90040-r.
Only part of the effect of dietary protein on urinary calcium excretion can be ascribed to sulfur amino acids. We hypothesized that chloride, another factor often associated with isolated proteins, and another amino acid, lysine, affect utilization of calcium. The effects of supplemental dietary chloride, inorganic or organic, on calcium, phosphorus, and magnesium utilization were studied in two rat studies. Weanling Sprague-Dawley rats were fed semi-purified diets that contained moderate (1.8 mg Cl/g diet) or supplemental (15.5 mg Cl/g diet) chloride as sodium chloride, potassium chloride, or lysine monohydrochloride with or without calcium carbonate for 56 or 119 days. Rats fed supplemental sodium chloride or potassium chloride had higher urinary phosphorus excretion, more efficient phosphorus absorption, but unchanged tissue phosphorus levels after 7 and 16 weeks of dietary treatment as compared to rats fed moderate chloride. Rats fed supplemental sodium chloride or potassium chloride excreted more calcium in urine at 7 weeks and absorbed calcium less efficiently at 16 weeks. Tissue calcium concentrations were unaffected, but total tibia magnesium and plasma magnesium concentrations were lower in rats fed supplemental sodium chloride or potassium chloride than those fed moderate chloride. Lysine chloride with or without additional calcium elevated urinary calcium excretion even more than sodium chloride and potassium chloride ingestion. Rats fed lysine chloride with supplemental calcium had smaller apparent absorption and urinary losses of phosphorus and magnesium after 16 weeks and lower tibia and plasma magnesium concentrations than rats fed lysine chloride.
膳食蛋白质对尿钙排泄的影响只有部分可归因于含硫氨基酸。我们推测，另一个常与单一蛋白质相关的因素——氯，以及另一种氨基酸——赖氨酸，会影响钙的利用。在两项大鼠研究中，我们研究了补充无机或有机氯化物对钙、磷和镁利用的影响。将断乳的斯普拉格-道利大鼠喂食半纯化日粮，日粮中含有适量（1.8毫克氯/克日粮）或补充量（15.5毫克氯/克日粮）的氯化物，分别以氯化钠、氯化钾或赖氨酸盐酸盐的形式存在，添加或不添加碳酸钙，持续56天或119天。与喂食适量氯化物的大鼠相比，喂食补充量氯化钠或氯化钾的大鼠在经过7周和16周的膳食处理后，尿磷排泄量更高，磷吸收更有效，但组织磷水平未变。喂食补充量氯化钠或氯化钾的大鼠在7周时尿钙排泄更多，在16周时钙吸收效率更低。组织钙浓度未受影响，但喂食补充量氯化钠或氯化钾的大鼠胫骨总镁和血浆镁浓度低于喂食适量氯化物的大鼠。无论有无额外添加钙，赖氨酸盐酸盐都会使尿钙排泄量比摄入氯化钠和氯化钾时增加得更多。与喂食赖氨酸盐酸盐的大鼠相比，喂食添加补充钙的赖氨酸盐酸盐的大鼠在16周后磷和镁的表观吸收和尿流失量更小，胫骨和血浆镁浓度更低。
