Whiting S J, Anderson D J, Weeks S J
College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada.
Am J Clin Nutr. 1997 May;65(5):1465-72. doi: 10.1093/ajcn/65.5.1465.
An acute load test was used to test the influence of dietary factors on urinary calcium excretion. In study 1, 10 fasting premenopausal women consumed test meals providing a moderate amount of protein (MP; 23 g), MP plus 23 mmol KHCO3 (MP+K), MP plus 23 mmol NaCl (MP+Na), and a high amount of protein (HP; 53 g), HP plus 70 mmol KHCO3 (HP+K), and HP plus 70 mmol NaCl (HP+Na). Protein was casein:lactalbumin (80:20), except for the treatments with added sodium chloride, to which only casein was added. In study 2, the effects of HP and HP plus 50 mmol KHCO3 (HP+K) were compared with those of MP or MP plus 7.5 mmol phosphate (MP+Pi), equaling the additional phosphate of HP, in 10 adult men. Subjects completed all treatments in random order. In study 1, the peak of calcium excretion was at 3 h for all treatments, except for HP+K, which indicated an acute hypocalciuric effect of potassium. Unexpectedly, there was no hypercalciuric effect of adding sodium chloride, nor was urine sodium increased. In study 2, calcium excretion was significantly higher with HP than with MP+Pi but not with MP at 3 h, indicating an acute hypercalciuric effect of protein alone. A hypocalciuric effect of potassium (HP+K compared with HP) but not of phosphate (MP compared with MP+Pi) was seen. An acute load test measuring changes 3 h postload was appropriate for examining the calciuric effects of protein and potassium bicarbonate, but not those of sodium chloride or phosphate in adults.
采用急性负荷试验来测试饮食因素对尿钙排泄的影响。在研究1中，10名空腹的绝经前女性食用了测试餐，这些测试餐分别提供适量蛋白质（MP；23克）、MP加23毫摩尔碳酸氢钾（MP + K）、MP加23毫摩尔氯化钠（MP + Na）、大量蛋白质（HP；53克）、HP加70毫摩尔碳酸氢钾（HP + K）以及HP加70毫摩尔氯化钠（HP + Na）。蛋白质为酪蛋白：乳白蛋白（80:20），添加氯化钠的处理组除外，该组仅添加了酪蛋白。在研究2中，比较了10名成年男性中HP以及HP加50毫摩尔碳酸氢钾（HP + K）与MP或MP加7.5毫摩尔磷酸盐（MP + Pi）（等同于HP额外添加的磷酸盐量）的效果。受试者以随机顺序完成所有处理。在研究1中，除HP + K外，所有处理的钙排泄峰值均出现在3小时，这表明钾具有急性降低尿钙的作用。出乎意料的是，添加氯化钠并没有导致高钙尿效应，尿钠也没有增加。在研究2中，3小时时HP组的钙排泄量显著高于MP + Pi组，但与MP组无显著差异，这表明单独蛋白质具有急性高钙尿效应。观察到钾（HP + K与HP相比）具有降低尿钙的作用，而磷酸盐（MP与MP + Pi相比）则没有。一项测量负荷后3小时变化的急性负荷试验适用于检测蛋白质和碳酸氢钾对尿钙的影响，但不适用于检测成年人中氯化钠或磷酸盐对尿钙的影响。
