Correlations between estimated and true dietary intakes: using two instrumental variables

PURPOSE: We describe a new application of the method of triads that allows an estimate of the correlation between a dietary questionnaire measure (Q) and true intake (T). METHODS: Three surrogate variables Q, M, and P are observed where M and P are both instrumental (often biological) variables. A reference dietary method (R) is not required. The variables M and P may be concentration rather than recovery biomarkers. Estimating equations produce Corr(Q,T), Corr(M,T), Corr(P,T), conditional on assumptions about error correlations. Correlations between errors in both Q and a reference dietary measure can also be estimated if R is available. A small validation study of California Seventh-day Adventists provided food frequency, repeated 24-hour dietary recalls (R), and biological data (blood, overnight urines, and subcutaneous fat). RESULTS: Values of Corr(Q,T) ranged between 0.40 and 0.66. Values of Corr(R,T) were higher, between 0.48 and 0.83. Estimated correlations between errors in R and Q were all positive. CONCLUSIONS: When carefully chosen, M and P, rather than M and R, should better satisfy assumptions about error correlations. Food frequency data and repeated 24-hour recalls both provide estimates of T, but the latter has greater validity. Standard errors suggest that for good precision Corr(Q,T) requires large validation studies (2000-3000 subjects).     

Comparison of estimated nutrient intakes by food frequency and dietary records in adults

Sixteen days of dietary recall and records collected over 1 year for 228 respondents were compared with an estimate of "usual" diet based on a 116-item food frequency questionnaire (FFQ) for the study year. Respondents were white and black men and women aged 24 to 51. Mean energy values for the total group were 2,111 kcal for the recall/records and 2,766 kcal for the FFQ, a 31% difference. The mean food energy and nutrient values obtained by the FFQ were consistently and significantly higher than the mean recall/record values for all four race-sex groups, although the degree of difference varied by nutrient, food group, and demographic characteristics of the respondents. For the nutrients compared, the smallest difference between methods was for protein--27% for the total group. The greatest difference was for vitamin A--123% for the total sample. Sex-race specific correlation coefficients between methods were relatively high for calcium, vitamin C, and iron.     

A comparison of dietary fibre intakes in South Wales estimated from a questionnaire and weighed dietary records

Intakes of dietary fibre in a random sample of 102 women living in a large South Wales village were measured by a four-day weighed dietary record and by questionnaire. The mean weekly intake of total dietary fibre calculated from the weighed records was 105.8g and that computed from questionnaires was 101.8g. The two methods indicated good agreement (r=0.51). Mean weekly cereal fibre intakes from weighed records and questionnaires were 46.6g and 46.4g respectively (r=0.69), and mean weekly fruit and vegetable fibre intakes were 59.2g and 55.4g respectively (r=0.34). The correlations were also good among a smaller group of 38 ‘health food shoppers’, consuming a high fibre diet. The questionnaire may therefore be used to obtain reliable data on dietary fibre intakes in free-living populations.     

学龄期儿童膳食多样化与微量营养素摄入量的关联性分析

目的 探究学龄期儿童膳食多样化与微量营养素摄入量的关系,为指导儿童科学饮食促进儿童健康提供科学依据。方法 课题组于2009年在江苏省射阳县建立关于儿童生长发育研究的出生队列,选取随访的442名6~7岁儿童作为研究对象。采用24 h膳食回顾调查评估儿童膳食状况,根据《中国食物成分表》估算微量营养素的摄入量并计算儿童膳食多样化评分(DDS和DDS₁₀)和食物多样性评分(FVS);同时评估儿童体格发育指标,应用多变量回归模型分析膳食多样化和微量营养素摄入量与儿童肥胖的关系。结果 研究地区儿童膳食微量营养素摄入量低于该年龄组的中国居民膳食营养素参考摄入量。三种儿童膳食多样化评分均值低于国内其他研究(DDS:6.69±1.59; DDS₁₀:4.94±1.51;FVS:16.79±7.53)。儿童膳食多样化评分与大部分微量营养素摄入状况均呈显著性正相关 (DDS:β=0.14~1.28; DDS₁₀:β=0.17~1.58 ; FVS:β=0.04~0.25,P<0.05),但膳食多样化评分与儿童肥胖无显著相关性(P>0.05)。结论 膳食多样化评分能从一定程度反映儿童微量营养素摄入的状况。倡导饮食多样化的膳食模式对促进儿童健康成长具有重要意义。     

Correlations between urinary concentrations and dietary intakes of flavonols in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

In this study, we aimed to study the correlation between acute and habitual intakes of flavonols, their main food sources and their 24-h urinary concentrat     

钙、奶及奶制品摄入量与超重肥胖的关系

目的调查成都市龙泉驿区7~15岁儿童青少年膳食钙、奶及奶制品摄入情况及超重肥胖现状,并探讨两者间的关系。方法采用分层整群随机抽样法,获1738例有效样本。利用24小时膳食问卷及食物频率问卷(FFQ)收集膳食信息,同时测量身高、体重及腰围,计算体质指数(BMI)、腰围身高比(WHtR),并进一步计算体质指数分数(BMI SDS)。根据中国肥胖问题工作组(WGOC)标准评价超重肥胖。将钙、奶及奶制品摄入量分成3组,分析超重肥胖指标与钙、奶及奶制品之间的关系。结果男生的超重率与肥胖率分别为11.92%、7.04%,女生为8.40%、6.30%。女生钙、奶及奶制品摄入量均高于男生(P0.0001)。7~9岁男生的BMI SDS与奶及奶制品摄入量成正比(P=0.01);10~12岁男生钙摄入量较低时,其超重率较高(P=0.03)。不同年龄组女生中,钙、奶及奶制品摄入情况与超重肥胖指标间的差异均无统计学意义。结论男生的钙、奶及奶制品摄入量可能与超重肥胖相关,但在不同年龄组中表现不同;女生中未发现钙、奶及奶制品与超重肥胖的关系。     

Associations between dietary intakes and blood cholesterol concentrations at 31 months

OBJECTIVE: The initial stages of atherosclerosis have been shown to occur in children as young as 3. Elevated total and LDL cholesterol concentrations and low HDL concentrations are a well-established risk factor for atherosclerosis. The objective of this study was to investigate the dietary determinants of blood lipid concentrations at 31 months of age. SUBJECTS: A randomly selected group of children (214 boys, 175 girls) in south-west England forming part of the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC) cohort. DESIGN: Three-day dietary records were obtained at 18 months. At 31 months a non-fasting blood sample was taken and analysed for total and HDL cholesterol and triglyceride, and measures of height and weight were taken. RESULTS: Among boys, total cholesterol concentrations were positively associated with the intake of total fat (r=0.209, P=0.002) and saturated fatty acids (r=0.211, P=0.002). Among girls, HDLC was positively associated with energy intake (r=0.204, P=0.018), and negatively associated with intakes of polyunsaturated fat, saturated fat and sugar in multivariate analysis. There were no associations between the intakes of non-starch polysaccharides (fibre) or dietary cholesterol and total or HDL cholesterol concentrations in either sex. Among boys, higher intakes of breakfast cereals were associated with lower total cholesterol (r=-0.187, P=0.008). Among girls, higher intakes of biscuits and meat and meat products were associated with higher HDLC concentrations. CONCLUSIONS: These data suggest that the dietary determinants of blood lipid concentrations differ between boys and girls. Reducing saturated fat intake in boys would be likely to lead to an improvement in blood lipid profiles. In this study there is no evidence to suggest that an increase in the intake of polyunsaturated fat by pre-school children would result in improved blood lipid profiles.     

糖尿病病人膳食生糖效应与膳食纤维摄入的关系研究

目的通过对膳食血糖指数(DGI)和膳食血糖负荷(DGL)的评估,研究膳食生糖效应与膳食纤维的关系。方法采用食物称重记账法调查105名2型糖尿病病人的2个3日膳食摄入状况,根据食物血糖指数和膳食碳水化合物摄入量计算DGI和DGL,采用酶-重量法测定食物中总膳食纤维(TDF)、不可溶性膳食纤维(IDF)和可溶性膳食纤维(SDF)含量。结果调查对象的DGI值是62.9±6.8,DGL值是142.4±39.8,TDF、IDF和SDF的摄入量分别是(22.5±6.7)g/d,(16.1±5.5)g/d,(6.4±2.0)g/d。DGI与TDF的相关系数是-0.407(P<0.01)。与DGI最低五分位组的调查对象相比,DGI最高五分位组的调查对象蔬菜类食物摄入量减少了221.9g(P<0.01),TDF、IDF和SDF摄入量分别减少了6.5g、5.0g和1.4g(P值均<0.01),其中由蔬菜提供的膳食纤维减少量最多,谷类摄入量增加了68.0g(P<0.01)。结论DGI与膳食纤维摄入量呈负相关。富含蔬菜和膳食纤维的膳食可降低膳食生糖效应。     

Relationship between calculated dietary and crude fiber intakes of 200 college students

Two hundred college students recorded dietary intakes for 2 consecutive days. Records were analyzed for 12 nutrients, and crude (CF) and dietary fiber (DF). Means of the 2 days were calculated to represent the daily intake of each student. The crude and dietary fiber provided by cereals and legumes, vegetables, fruits, and miscellaneous sources were determined for a subpopulation of 50 students. Mean (+/-SD) daily CF intake of the population was 4.07 +/- 2.17 g, of DF, 15.36 +/- 7.96 g. When related to energy intake, women (n = 143) consumed significantly more CF and DF than the men (n = 57). Only the cereal and legume group provided appreciably more DF than CF, 32.4 versus 18.8%, of the total daily intake of the subpopulation. The mean DF: CF ratio for the population was 3.9 +/- 1.0 and intakes of the two measures of fiber were highly correlated, r = 0.86. Intakes of CF/1000 kcal and the number of servings of cereal products may indicate when the daily DF intake is less than or equal to 3 or greater than or equal to 5 times the daily CF intake. These data suggest that for the majority of the college-aged population we studied, who consumed a wide variety of foods, a daily DF intake ranged from 3 to 5 times the daily CF intake.     

Agreement of estimated values with measured values in dietary intakes of minerals: A validation study in Japan

This study was initiated to examine the validity of newly published food composition tables (FCT) as a tool for estimation of mineral intakes in Japan. For this purpose, 24-hour food duplicate samples were collected from residents in two areas. In practice, 24 adult women in one area and 17 adults (men and women) in the other offered complete samples (i.e. the samples with which the energy intakes were ≧1.2 times basal metabolic rates). The concentrations of nine minerals (Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) in the duplicates were estimated by use of FCT, and compared with the values measured by flame atomic absorption spectrometry or inductively-coupled plasma atomic emission spectrometry. Close agreement was observed between the estimated values (E) and the measured values (M) on a group basis; the E/M ratios were in a range of 0.92–1.26. Lower limits of the 95% confidence interval of the ratio were, however, low, i.e. 0.42 for Ca, 0.54 for Na and 0.59 for Fe. The risk of over-estimation was highest for Mg (by +26%), Fe (by +22%) and Mn (by +22%). Thus, it appeared prudent to conclude that FCT-based estimation is reliable on a group basis for the minerals studied, and that care should be practiced, however, when application is made on an individual basis, especially for Ca, Fe and Na.     

2000年中国总膳食研究—膳食砷摄入量

目的了解和评价2000年中国不同地区膳食中总砷及无机砷的含量和成年男子人均膳食摄入量。方法采用总膳食研究方法,通过膳食调查、统计不同地区人群各种食物的消费量、按照所得的食物消费量数据烹调加工并混合成可食的各种食物类别。膳食样品中总砷含量采用氢化物发生原子吸收光谱法,无机砷含量采用氢化物发生原子荧光法测定,并按成年男子各种食品的消费量与实测膳食中砷的含量相乘得到不同地区总砷及无机砷的实际摄入量。采用世界卫生组织推荐的无机砷每周可耐受摄入量(PTWI)值评价我国4个大区成年男子膳食中无机砷摄入的安全性。结果某些地区的个别食物样品超过我国的食品卫生中砷的限量标准。我国4个大区(北方一区,北方二区,南方一区,南方二区)和中国标准人膳食中总砷和无机砷摄入量(占PTWI百分率)分别为:0.220mg,0.094mg(69.3%);0.254mg,0.098mg(72.2%);0.296mg,0.048mg(35.6%);0.335mg,0.077mg(57.3%)和0.276mg,0.079mg(58.6%)。结论本研究首次运用总膳食的方法得到我国4个大区成年男子和中国标准人膳食中总砷及无机砷摄入量数据。结果显示我国人群膳食中总砷及无机砷摄入量是安全的。     

Changes in dietary intakes with age

The aim of this study was to describe changes in dietary intakes with age in subjects aging normally within the Toulouse study. Daily caloric intakes were constant in both sexes and in the three age classes considered. Energy distributions among the meals were rather clearly modified in men: the contribution of breakfast and afternoon snacks increased while those of lunch and dinner decreased. Observations among women were less consistent but the contribution of dinner also decreased with age (from 33.3 to 30.7%). This decreased contribution from dinner was due to a change in its nutrient composition (fewer lipids and more carbohydrates) which change the nutrient constitution of the entire daily diet, and also from a change in structure (reduced contribution by the main dish and increased role of desserts). These results pose questions concerning the reasons behind this change (loss of appetite, more pronounced taste for sweets?) and requires additional study.     

Use of nutritional supplements among Mexican women and the estimated impact on dietary intakes below the EAR and above the UL

OBJECTIVE: To describe supplement use practices among non-pregnant, non-lactating Mexican women (12-49 y) and estimate their impact on the proportion of women with intakes below the Estimated Average Requirement (EAR) and above the Upper Limit (UL) using data from a national probabilistic nutrition survey in Mexico (1999). METHODS: Information was collected by questionnaire on the frequency and duration of supplement use in the previous 6 months (n = 17,794). Dietary intakes by 24-hour recall were determined in a representative sub-sample (n = 2,599). Frequency of use and available information on the nutrient content of supplements was used to estimate daily equivalent intakes. RESULTS: 17.6% of women reported to have used supplements. The majority of these took supplements once daily (71%) and for < or =2 months (75%). While nutrient intakes from diet alone did not differ between users and non-users, the proportion with intakes of Vitamins A, B(6), B(12), and C, folate, iron, and zinc < EAR were significantly greater among the supplement non-users when intakes from supplements were also considered. The proportion of women with intakes > UL was greater among supplement users than non-users for iron, folate and Vitamin B(6). CONCLUSION: Supplement use contributes to the adequacy of nutrient intakes but may also increase the possible risk of toxic intakes of some nutrients among Mexican women.     

Associations between eating patterns, dietary intakes and eating behaviors in premenopausal overweight women

The regulation of energy intake is complex and many biological, psychosocial and environmental influences have been identified. To our knowledge, no study has yet investigated how eating patterns could mediate associations between eating behaviors and self-reported energy intake in premenopausal overweight women. Therefore, objectives of this study were to examine associations between eating behaviors and eating patterns in premenopausal overweight women and to test if eating patterns could mediate the associations between eating behaviors and self-reported energy intake. Women completed a 3-day food record and the Three-Factor Eating Questionnaire was used to assess eating behaviors (dietary restraint, disinhibition, hunger). In the total sample of women, flexible restraint was negatively (r=-0.18; p=0.03) and binge eating severity was positively (r=0.24; p=0.004) associated with self-reported energy intake. Moreover, flexible restraint was positively associated with the proportion of energy intake at breakfast (r=0.24; p=0.004), whereas disinhibition and binge eating severity were positively associated with the proportion of energy intake from snacks consumed after 5:00 pm (r=0.22, p=0.007 and r=0.22, p=0.01, respectively). In addition, mediational analyses showed that proportion of energy intake from snacks consumed after 5:00 pm explained 24.1% of the association between binge eating severity and self-reported energy intake. In conclusion, these results suggest that eating patterns are important factors to consider in order to explain the associations between eating behaviors and self-reported energy intake.