Charlton Karen E, Steyn Krisela, Levitt Naomi S, Zulu Jabulisiwe V, Jonathan Deborah, Veldman Frederick J, Nel Johanna H
Chronic Diseases of Lifestyle Programme, Medical Research Council, Tygerberg, South Africa.
Eur J Cardiovasc Prev Rehabil. 2005 Aug;12(4):355-62. doi: 10.1097/01.hjr.0000170265.22938.d1.
To determine any differences in the urinary excretion and dietary intake of sodium, potassium, magnesium and calcium intake in three South African ethnic groups, and to assess whether the blood pressure-cation association varies according to ethnic status.
A cross-sectional study of 325 black, white and mixed-ancestry men and women, conveniently sampled in Cape Town. Twenty-four-hour urine samples were collected on three separate occasions for assessment of urinary electrolytes, and three 24-h dietary recalls for the corresponding urine collection times were administered by two trained fieldworkers. Para-amino benzoic acid was used as a marker of the completeness of urine collection.
Mean urinary sodium values equate to a daily salt (sodium chloride) intake of 7.8, 8.5 and 9.5 g in black, mixed-ancestry and white individuals, respectively. In normotensive individuals, black and mixed-ancestry subjects had significantly lower median urinary sodium concentrations than white subjects, but these differences were not evident between black and white hypertensive subjects. No ethnic differences were found for urinary potassium, except for mixed-ancestry normotensive individuals having a lower excretion than white normotensive individuals. Urinary magnesium excretion did not differ across ethnic groups. In both normotensive and hypertensive individuals, urinary calcium concentrations differed between all three groups, with black subjects having the lowest values, approximately less than half those of white subjects.
White normotensive subjects in Cape Town have higher habitual intakes of sodium, but also higher calcium intakes than their black and mixed-ancestry counterparts. Dietary differences may contribute to ethnic-related differences in blood pressure.
确定南非三个种族群体钠、钾、镁和钙的尿排泄量及饮食摄入量的差异，并评估血压与阳离子的关联是否因种族状况而异。
对开普敦325名黑人、白人和混血男女进行横断面研究，采用方便抽样。在三个不同时间收集24小时尿液样本以评估尿电解质，并由两名经过培训的现场工作人员对与相应尿液收集时间对应的三次24小时饮食回忆进行调查。对氨基苯甲酸用作尿液收集完整性的标志物。
黑人、混血和白人个体的尿钠平均值分别相当于每日盐（氯化钠）摄入量7.8、8.5和9.5克。在血压正常的个体中，黑人和混血受试者的尿钠中位数浓度显著低于白人受试者，但在黑人和白人高血压受试者之间这些差异不明显。除了混血血压正常个体的排泄量低于白人血压正常个体外，尿钾在种族间未发现差异。尿镁排泄量在各民族间无差异。在血压正常和高血压个体中，三组的尿钙浓度均有差异，黑人受试者的值最低，约为白人受试者的一半以下。
开普敦的白人血压正常受试者钠的习惯性摄入量较高，但钙摄入量也高于黑人和混血受试者。饮食差异可能导致血压的种族相关差异。
