Underreporting of energy, protein and potassium intake in relation to body mass index.
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BACKGROUND: Differential underreporting of dietary intake by subgroups of body mass index (BMI) will confound associations between dietary intake and BMI-related diseases. We estimated the magnitude of BMI-related underreporting for energy, protein, and potassium intake for the Dutch cohorts of the European Prospective Investigation into Cancer and Nutrition (EPIC). METHODS: The study population consisted of 134 Dutch men and women, aged 21-71 years, who participated in a pilot of EPIC. Ratios of reported dietary intakes to biomarkers were used as measures for underreporting. Dietary intake was assessed by a food frequency questionnaire (FFQ) and repeated 24-hour dietary recalls. Biomarker for energy intake was calculated basal metabolic rate; for protein and potassium intake the biomarker was 24-hour urinary nitrogen and potassium excretion, respectively. The measures of underreporting were linearly regressed on BMI (in kg/m2). RESULTS: Significant negative regression coefficients were observed when regressing energy ratio on BMI with adjustment for physical activity (FFQ: beta = -0.04 for men, beta = -0.02 for women; 24-hour recalls: beta = -0.03 for men, beta = -0.04 for women). In men, a significant negative regression coefficient (beta = -0.03) was observed when regressing protein ratio on BMI; for the recalls however only after adjustment for age and education (beta = -0.02). In women, negative regression coefficients were also obtained, but for the FFQ only after exclusion of dieting women (both FFQ and 24-hour recalls: beta = -0.02). According to the recalls, but not the FFQ, a significant negative regression coefficient (beta = -0.02) was observed among women when regressing potassium ratio on BMI. CONCLUSIONS: In this Dutch population, BMI-dependent underreporting of 20-25% over the observed range of BMI is present for protein and energy, Further study on BMI-dependent underreporting of dietary intake in EPIC cohorts is warranted. (+info)
alpha-1-Microglobulin: epidemiological indicator for tubular dysfunction induced by cadmium?
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OBJECTIVES: To evaluate the suitability of alpha-1-microglobulin as a marker for cadmium induced renal dysfunction. METHODS: alpha-1-Microglobulin was studied in a cross sectional survey in relation to the body burden of cadmium. Concentrations of alpha-1-microglobulin in 24 h urine of 831 people aged 2-87 years were analysed in association with urinary cadmium excretion, cadmium blood concentration, age, sex, occupational and smoking history, and estimated creatinine clearance. Participants came from a population residentially exposed to cadmium and from two control populations matched for socioeconomic status. RESULTS: The excretion of alpha-1-microglobulin/24 h ranged from 0.1 mg to 176.3 mg and 44.4% of samples showed concentrations near the detection limit. Ordinal logistic regression analysis of people of all ages identified a high risk only for males compared with females (odds ratio (OR) 2.14; 95% confidence interval (95% CI) 1.56 to 2.94), age group, and duration of living on contaminated soil (OR 1.03/year; 95% CI 1.02 to 1.04), but not urinary cadmium excretion (OR 1.30; 95% CI 0.96 to 1.77) as significant predictors. For people < or = 50 years of age a weaker effect of sex (OR 1.76; 95% CI 1.13 to 2.73) and age group and an effect of similar magnitude for the duration of soil exposure (OR 1.03; 95% CI 1.01 to 1.04) were found. Also, the urinary cadmium excretion (OR 2.26; 95% CI 1.38 to 3.70) and occupational exposure (OR 1.71; 95% CI 1.03 to 2.83) were found to be significant in this younger age group. The estimated creatinine clearance had no significant impact on the alpha-1-microglobulin excretion. CONCLUSION: alpha-1-Microglobulin is a suitable marker for early tubular changes only for people < or = 50 years. It may not be sufficiently specific for cadmium, and therefore not a suitable surrogate for cadmium exposure in epidemiological studies. (+info)