Department of Public Health, Ghent University, Belgium.
Int J Obes (Lond). 2011 Apr;35 Suppl 1:S69-78. doi: 10.1038/ijo.2011.37.
Measuring dietary intake in children is notoriously difficult. Therefore, it is crucial to evaluate the performance of dietary intake assessment methods in children. Given the important contribution of milk consumption to calcium (Ca) and potassium (K) intakes, urinary calcium (UCa) and potassium (UK) excretions in spot urine samples could be used for estimating correlations with milk consumption frequencies.
The aim of this study was to evaluate the assessment of milk consumption frequencies derived from the Food Frequency Questionnaire section of the Children's Eating Habits Questionnaire (CEHQ-FFQ) used in the IDEFICS (Identification and prevention of dietary- and lifestyle induced health effects in children and infants) study by comparing with UCa and UK excretions in spot urine samples.
This study was conducted as a setting-based community-oriented intervention study and results from the first cross-sectional survey have been included in the analysis.
A total of 10,309 children aged 2-10 years from eight European countries are included in this analysis.
UCa and UK excretions were measured in morning spot urine samples. Calcium and potassium urine concentrations were standardised for urinary creatinine (Cr) excretion. Ratios of UCa/Cr and UK/Cr were used for multivariate regression analyses after logarithmic transformation to obtain normal distributions of data. Milk consumption frequencies were obtained from the CEHQ-FFQ. Multivariate regression analyses were used to investigate the effect of milk consumption frequencies on UCa and UK concentrations, adjusting for age, gender, study centre, soft drink consumption and frequency of main meals consumed at home.
A significant positive correlation was found between milk consumption frequencies and ratios of UK/Cr and a weaker but still significant positive correlation with ratios of UCa/Cr, when using crude or partial Spearman's correlations. Multivariate regression analyses showed that milk consumption frequencies were predictive of UCa/Cr and UK/Cr ratios, when adjusted for age, gender, study centre, soft drink consumption and frequency of main meals consumed at home. Mean ratios of UK/Cr for increasing milk consumption frequency tertiles showed a progressive increase in UK/Cr. Children consuming at least two milk servings per day had significantly higher mean UCa/Cr and UK/Cr ratios than children who did not. Large differences in correlations between milk consumption frequencies and ratios of UCa/Cr and UK/Cr were found between the different study centres.
Higher milk consumption frequencies resulted in a progressive increase in UK/Cr and UCa/Cr ratios, reflecting the higher Ca and K intakes that coincide with increasing milk consumption, which constitutes a major K and Ca source in children's diet.
儿童的膳食摄入量很难准确测量。因此，评估膳食摄入量评估方法在儿童中的表现至关重要。鉴于牛奶消费对钙（Ca）和钾（K）摄入量的重要贡献，可通过测定单次尿样中的尿钙（UCa）和尿钾（UK）排泄量来估计与牛奶消费频率的相关性。
本研究旨在通过比较 IDEFICS（儿童和婴儿饮食和生活方式诱导的健康影响的识别和预防）研究中儿童饮食习惯问卷（CEHQ-FFQ）的食物频率问卷部分得出的牛奶消费频率与单次尿样中的 UCa 和 UK 排泄量，评估该方法的准确性。
本研究为基于社区的定向干预研究，分析中纳入了首次横断面调查的结果。
共有来自 8 个欧洲国家的 10309 名 2-10 岁儿童参与了此项研究。
清晨采集单次尿样，测定 UCa 和 UK 排泄量。尿肌酐（Cr）排泄量对钙和钾尿浓度进行标准化。对数转换后，采用 UCa/Cr 和 UK/Cr 比值进行多元回归分析，以获得数据的正态分布。牛奶消费频率来自 CEHQ-FFQ。多元回归分析用于研究牛奶消费频率对 UCa 和 UK 浓度的影响，同时调整年龄、性别、研究中心、软饮料消费和在家中食用主餐的频率。
在使用未校正或部分 Spearman 相关系数时，牛奶消费频率与 UK/Cr 比值呈显著正相关，与 UCa/Cr 比值呈较弱但仍有显著正相关。多元回归分析表明，在校正年龄、性别、研究中心、软饮料消费和在家中食用主餐频率后，牛奶消费频率可预测 UCa/Cr 和 UK/Cr 比值。随着牛奶消费频率递增的 tertiles，UK/Cr 比值呈递增趋势。每天至少摄入两份牛奶的儿童的 UCa/Cr 和 UK/Cr 比值显著高于不摄入牛奶的儿童。不同研究中心之间，牛奶消费频率与 UCa/Cr 和 UK/Cr 比值的相关性差异较大。
牛奶消费频率的增加与 UK/Cr 和 UCa/Cr 比值的增加呈正相关，这反映了与牛奶消费频率增加相对应的更高的 Ca 和 K 摄入量，而牛奶是儿童饮食中 K 和 Ca 的主要来源。
