Serum transferrin receptor concentration indicates increased erythropoiesis in Kenyan children with asymptomatic malaria.

BACKGROUND: Serum transferrin receptor concentrations indicate both erythropoietic activity and the deficit of functional iron in the erythron. In contrast with serum ferritin concentrations, serum transferrin receptor concentrations are not or are only marginally influenced by the inflammatory response to infection. OBJECTIVE: We assessed iron status and examined the relation between serum transferrin receptor concentrations and malaria in children aged 2-36 mo who were asymptomatic for malaria. DESIGN: This was a community-based cluster survey (n = 318). RESULTS: Prevalences of malaria, anemia (hemoglobin concentration <110 g/L), iron deficiency (serum ferritin concentration <12 microg/L), and iron deficiency anemia were 18%, 69%, 53%, and 46%, respectively. Malaria was associated with lower mean hemoglobin concentrations (92.7 compared with 104.1 g/L; P = 0.0001) and higher geometric mean serum concentrations of transferrin receptor (11.4 compared with 7.8 mg/L; P = 0.005), ferritin (21.6 compared with 11.9 microg/L; P = 0.05), and C-reactive protein (12.5 compared with 6.8 mg/L; P = 0.004). There was no evidence for an association between serum concentrations of C-reactive protein and transferrin receptor. Children with malaria had higher serum transferrin receptor concentrations than expected for the degree of anemia, even after adjustment for inflammation indicated by serum C-reactive protein concentration quartiles (P = 0.02). CONCLUSIONS: Our findings are consistent with the notion that malaria-induced hemolysis is accompanied by increased erythropoiesis. Serum transferrin receptor concentration is not useful for detecting iron deficiency in individuals with malaria. Individuals with high concentrations of serum C-reactive protein or similar acute phase reactants should be excluded from analysis if serum ferritin concentrations <12 microg/L are to be used to measure iron deficiency in malaria-endemic areas.

Nutritional status of breastfed infants in rural Zambia: comparison of the National Center for Health Statistics growth reference versus the WHO 12-month breastfed pooled data set.

Cross-sectional data for breastfed infants in rural Zambia were used to evaluate the effect of applying two different data sets as a reference, i.e. the WHO 12-month breastfed pooled data set and the National Center for Health Statistics (NCHS) growth reference in terms of prevalence of malnutrition (stunting, underweight, and wasting). A total of 518 infants who were attending mother-and-child health clinics were included. Age, weight and length were recorded. Anthropometric Z-scores were calculated in two ways: by applying the NCHS growth reference and by using the WHO breastfed data set. Anthropometric Z-scores calculated using the breastfed data set were lower during the first 6-7 months of life compared with those calculated by applying the NCHS growth reference. This resulted in a higher proportion of children aged 0-6 months being classified as stunted and underweight using the breastfed data set versus the NCHS growth reference. After the age of 7 months, similar prevalences of stunting or underweight were observed. Relatively few infants were classified as wasted. In order to adequately assess the prevalence of stunting and underweight in breastfed infants, it is recommended that a new growth reference be developed, as has been initiated by WHO.

Effect of dialysate temperature on energy balance during hemodialysis: quantification of extracorporeal energy transfer.

An impaired vascular response is implicated in the pathogenesis of dialysis-induced hypotension, which is at least partly related to changes in extracorporeal blood temperature (Temp). However, little is known about changes in core Temp and differences in energy balance between standard and cool dialysis. In this study, core Temp and energy transfer between extracorporeal circuit and patient, as well as the blood pressure response, were assessed during dialysis with standard (37.5 degrees C) and cool (35.5 degrees C) Temp of the dialysate. Nine patients (4 men, 5 women; mean age, 69 +/-10 [SD] years) were studied during low- and standard-Temp dialysis, each serving as his or her own control. Bicarbonate dialysis and hemophane membranes were used. Energy transfer was assessed by continuous measurement of Temp in the arterial (Tart) and venous side (Tven) of the extracorporeal system according to the formula: c. rho.Qb*(Tven - Tart)*t, where c = specific thermal capacity (3.64 kJ/kg* degrees C), Qb = extracorporeal blood flow, rho = density of blood (1,052 kg/m3), and t = dialysis time (hours). Core Temp was also measured by Blood Temperature Monitoring (BTM; Fresenius, Bad Homburg, Germany). Core Temp increased during standard-Temp dialysis (36.7 degrees C +/- 0.3 degrees C to 37.2 degrees C +/- 0.2 degrees C; P < 0.05) despite a small negative energy balance (-85 +/- 43 kJ) from the patient to the extracorporeal circuit. During cool dialysis, energy loss was much more pronounced (-286 +/- 73 kJ; P < 0.05). However, mean core Temp remained stable (36.4 degrees C +/- 0.6 degrees C to 36.4 degrees C +/- 0.3 degrees C; P = not significant), and even increased in some patients with a low predialytic core Temp. Both during standard and cool dialysis, the increase in core Temp during dialysis was significantly related to predialytic core Temp (r = 0.88 and r = 0.77; P < 0.05). Systolic blood pressure (RR) decreased to a greater degree during standard-Temp dialysis compared with cool dialysis (43 +/- 21 v 22 +/- 26 mm Hg; P < 0.05), whereas diastolic RR tended to decrease more (15 +/- 10 v 0 +/- 19 mm Hg; P = 0.07). Core Temp increased in all patients during standard-Temp dialysis despite a small net energy transfer from the patient to the extracorporeal system. Concluding, Core Temp remained generally stable during cool dialysis despite significant energy loss from the patient to the extracorporeal circuit, and even increased in some patients with a low predialytic core Temp. The change in core Temp during standard and cool dialysis was significantly related to the predialytic blood Temp of the patient, both during cool- and standard-Temp dialysis. The results suggest that the hemodialysis procedure itself affects core Temp regulation, which may have important consequences for the vascular response during hypovolemia. The removal of heat by the extracorporeal circuit and/or the activation of autoregulatory mechanisms attempting to preserve core Temp might be responsible for the beneficial hemodynamic effects of cool dialysis.

The SENECA study: potentials and problems in assessing dietary changes over time.

In 1988 a European multicenter study, named SENECA, was initiated. Nine of the original 19 participating towns in 12 European countries decided to continue the longitudinal study by conducting a second survey in 1993. The aim of the longitudinal part of the SENECA study was to provide measurements of diet, lifestyle, health and performance as such at two points in time and to analyze the direction of changes and possible interrelationships between the factors studied. For the present paper the experience with the SENECA study has been used to illustrate the problems related to nutritional longitudinal studies in different stages of dietary research. In the examples we have focused on results relating changes in body weight to energy intake and changes in total cholesterol to intakes of fat and fatty acids of participants from four SENECA sites. To examine dietary habits a modified dietary history was chosen consisting of two parts: an estimated record and a checklist of foods. The results demonstrate that the special design of the study and adaptation of methods made it possible to deal with several problems encountered in nutritional longitudinal studies in elderly people. Nevertheless the changes in diet are most likely underestimated. Consequently in the interpretation of data and further analysis we have to consider this problem as well as other remaining problems.

Errors in the interpretation of dietary assessments.

Two years ago, I reviewed the analytic effect of error in the estimation of dietary intake, describing the emphasis on the "random" day-to-day variation in reported intake. Interest in this area is increasing and there are signs of progress in analytic strategies. This paper focuses on two concerns about the use of dietary data in analyses. The effect of different methods of adjusting analyses of fat and a health outcome for energy is illustrated through an exploration of the association between fat intake and high body mass index in data sets from the US Department of Agriculture and a Dutch national survey. Both a shift in the analytic question and a change in the error structure occur as analysis strategies are changed, leading to confusion in interpretation. The paper also addresses the growing concern about bias in the estimation of intake and the possibility that differential bias moves with stratification variables of analytic interest. The increasing use of doubly labeled water estimates of energy expenditure as a gold standard for checking on overall bias in reporting is commendable. There will always be error in dietary assessments. The challenge is to understand, estimate, and make use of the error structure during analysis.

Experts' subjective assessment of pesticide exposure in fruit growing.

OBJECTIVES: Exposure to pesticides in fruit growing was estimated by pesticide experts, occupational hygienists, and fruit growing experts to determine whether valid subjective assessments can be made by experts. The study objectives were (i) validation of exposure assessment by experts using different sources of information, (ii) assessment of interrater agreement, (iii) measurement of agreement between experts' assessments and actual quantitative exposure data. METHODS: Three groups with different expertise made four ratings. Three of the ratings were made in three phases in which exposure information was provided. RESULTS: The intraclass correlation was high for each subgroup of experts when tasks in fruit growing were relatively ranked by increasing exposure level. In general, the interrater agreement on factors influencing the internal dose decreased when more information on exposure was provided. Experts correctly considered dermal exposure as the prominent contributor to internal dose. Results were comparable for the three pesticides under study. The ranking of 15 specific sprayings with a fungicide clearly showed differences between raters according to their expertise. The pesticide experts and occupational hygienists were able to rank daily exposure levels during pesticide spraying in a meaningful way. CONCLUSIONS: Experts seem to recognize the most important determinants of external exposure and therefore should be able pay a role in evaluating the effectiveness of control measures taken to reduce external exposure and to determine exposure groups in epidemiologic studies. The expert panel should not be too small, and consensus or average estimates should be used because differences within expert groups can be considerable.

Calcium does not protect against colorectal neoplasia.

Calcium could decrease risk of colorectal neoplasia by binding bowel-irritating compounds and diminishing mucosal proliferation. This study quantitatively summarizes epidemiologic studies addressing this hypothesis and aims to explain heterogeneity between studies. Twenty-four articles reported 43 measures of relative risks (RRs). The weighted mean, according to a random effects model, did not indicate substantial protection by calcium [RR = 0.89; 95% confidence interval (CI) = 0.79-1.01]. Results from different studies showed substantial heterogeneity, with the "true" underlying RRs ranging from about 0.50 to 1.60. Summary RRs for cohort and case-control studies were 0.90 and 0.88, respectively. For adenomas and carcinomas, RRs were 1.13 (95% CI = 0.91-1.39) and 0.86 (95% CI = 0.74-0.98), respectively, both falling within the range of between study heterogeneity. With respect to subsites, lower RRs were observed for estimates that included proximal colon as one of the subsites (RR = 0.67), whereas the RR was close to 1.0 for distal (RR = 0.97) and rectal subsites (RR = 0.99). Stratification on study characteristics and weighted regression analysis yielded RRs slightly below 1.0, with considerable heterogeneity. These results do not support the hypothesis that calcium prevents colorectal neoplasia.

Assessment of bias in the SENECA study.

OBJECTIVE: To assess manifest bias in ageing effects, i.e. longitudinal changes due to unintended time effects or to selection. DESIGN: Mixed-longitudinal study in birth cohorts 1913-1918, with baseline measurements taken in 1988/1989 and repeated in 1993, including a short questionnaire in non-responders. SETTING: Full baseline and follow-up data were collected in nine towns in eight European countries including Belgium, Denmark, France, Italy, The Netherlands, Portugal, Spain and Switzerland. Incomplete data were available from towns in Portugal, Poland, Northern Ireland and Connecticut, USA. SUBJECTS: Using standardized methodologies data were collected from a random age-stratified sample of elderly men and women, including a total of 1221 re-invited subjects from nine towns and 210 newly-invited subjects from three towns in 1993. RESULTS: An overall retrieval of 50-74% of the former participants could be reached in towns that had previously participated (apart from one exception of 41%), where estimates of mortality varied from 10% to 18%. There was a tendency for healthy and active persons to have a higher participation rate than others, as was the case for high educated newly-invited subjects compared to lower educational classes. For most of the variables used in the analysis of period effects, no evidence of any undesirable period effect was found. In those instances that period effects showed up to be statistically significant, coinciding implausible cohort effects gave the impression that these were due to instability of the estimation procedure. CONCLUSIONS: Non-participants may be less healthy and active than the participants. Only very limited unconvincing evidence to suggest unintended time effects was observed. This confirms the high standards of the methodology and of measurements.

Evaluation of the dietary history method used in the SENECA Study.

OBJECTIVE: To evaluate a modified dietary history method applied in elderly people aged 74-79 y. SETTING AND SUBJECTS: A total of 387 men and 420 women from seven European towns participated in an observational study. METHODS: Dietary intake was assessed with a modified dietary history and compared with a 3-day estimated record. RESULTS: The modified dietary history provided consistently higher intakes of energy and nutrients than the estimated record. For most nutrients this difference was between 10% and 20%. However, in some towns differences were much larger. Physical activity ratios calculated as reported energy intake divided by estimated basal metabolic rate (BMR) showed values less than 1.5 for data obtained with the estimated record, suggesting underreporting of energy intake. Pearson correlation coefficients between estimates by the two methods of the intakes of energy and almost all nutrients ranged from approximately 0.5 to 0.75. CONCLUSION: The size of the overall correlation coefficients indicates an acceptable agreement between the dietary history and record method in ranking individuals according to their intakes. For two towns, this agreement was not that good. Results indicate that the estimated record might not be a good reference method for older adults.

Survival beyond age 70 in relation to diet.

Overall survival was studied in men and women over 70 years of age in relation to the Greek variant of the traditional Mediterranean diet. According to a dietary score based on eight characteristics, a significant 17% reduction in overall mortality was observed with each unit increase in diet score. The results suggest that closer adherence to the traditional Greek diet favorably affects life expectancy among elderly people.

Psychophysical and psychohedonic functions of four common food flavours in elderly subjects.

This study was designed to determine the cause of potential differences in optimal preferred flavour concentrations in four common food items between young and elderly subjects. The main objective was to investigate whether the differences in concentration-pleasantness functions could be attributed to differences in concentration-intensity (psychophysical) functions, or to differences in intensity-pleasantness (psychohedonic) functions. Groups of elderly subjects (n = 31) and young subjects (n = 25) judged four series of food items (bouillon, tomato soup, chocolate custard and orange lemonade), each with five geometrically spaced flavour concentration levels. In addition, all participants judged a series of grey surfaces as a reference series. Stimuli were judged on a 10-point scale with respect to perceived intensity and pleasantness. The results showed that the responses to the various stimuli in the series of grey surfaces were almost equivalent for young and elderly subjects. The older subjects had higher optimal flavour concentrations than young subjects for each of the four food items. The differences could be attributed to differences in both psychophysical and psychohedonic functions for all four flavours. However, changes in psychohedonic functions were less pronounced for the savoury flavours than for the sweet flavours. The higher optimal preferred flavour concentration level for the elderly could be partly explained by the phenomenon that the elderly need higher concentration levels than young subjects in order to obtain a similar perceived intensity level.

Nutrition knowledge and attitudes towards high-fat foods and low-fat alternatives in three generations of women.

OBJECTIVES: To assess family resemblance in food habits in three generations of maternally related family members. DESIGN AND SUBJECTS: Ninety-seven adult women, their mothers and grandmothers were asked about nutrition knowledge, attitudes and fat intake. Nutrition knowledge and attitudes were determined by means of a self-administered questionnaire. A food frequency questionnaire was used to assess fat intake. RESULTS: Mean percentage energy derived from fat was 39% for the younger generation, and 40% for their mothers and grandmothers. Generations differed in their nutrition knowledge score (P <0.0001), the grandmothers having a lower nutrition knowledge than the other generations. Correlations of nutrition knowledge scores were 0.30 (95% confidence limits (c.l.) 0.10 and 0.48) between the younger and middle generations, 0.35 (95% c.l. 0.16 and 0.52) between the middle and older generations, and 0.14 (95% c.l. -0.06 and 0.34) between the younger generation and their grandmothers. For attitudes towards high-fat foods and their low-fat alternatives these figures were 0.27 (95% c.l. 0.07 and 0.45), 0.22 (95% c.l. 0.01 and 0.41), and 0.17 (95% c.l. - 0.03 and 0.36), respectively, while for energy percentage of fat intake the correlations were only 0.19 (95% c.l. -0.01 and 0.37), -0.02 (95% c.l. -0.22 and 0.18), and 0.12 (95% c.l. limits - 0.08 and 0.31), respectively. Within generations the correlations between attitudes and nutrition knowledge or percentage energy derived from fat were found to be higher in the middle generation than in other generations. No statistically significant correlations were found between nutrition knowledge and percentage energy derived from fat. CONCLUSIONS: From this study it can be concluded that mothers and their adult daughters resemble each other in nutrition knowledge and attitudes.

Family resemblance in beliefs, attitudes and intentions towards consumption of 20 foods; a study among three generations of women.

Family resemblance in beliefs, attitudes and intentions towards the consumption of 20 foods that contribute to the fat intake was investigated in 97 adult women, their mothers and their grandmothers. Mean correlation for elements from the Fishbein and Ajzen theory of reasoned action between younger and middle generations ranged from 0.09 to 0.17 and between middle and older generations from 0.12 to 0.17. All significant correlations were positive. More statistically significant correlations were found for liking attitudes between the younger and middle generations (p < 0.05 for ten out of 20 correlations) than for other pairs. Between the older and younger generation the number of significant correlations could be due to chance alone. From the relative importance of liking and good/bad attitude on intention it appeared that liking contributed the most to the variance in intention scores. Health related beliefs and attitudes became of increasing importance in the older generations. From this study it can be concluded that mothers and their adult daughters resemble each other in beliefs, food preferences, attitudes and intentions, although resemblance is poor.

Reproducibility of a semiquantitative food frequency questionnaire to assess the intake of fats and cholesterol in The Netherlands.

The reproducibility of a 104 item semiquantitative food frequency questionnaire to estimate the intake of energy, fat, fatty acids and cholesterol was assessed in a group of 93 men and women in the Netherlands. The questionnaire was administered by trained interviewers. Subjects were asked to recall the consumption of 104 items during the past month. A second interview was conducted 8 weeks later. The mean difference in nutrient intake between the two assessments was very small, with a maximum of 5% for cholesterol intake, but the variance of individual differences was considerable. Pearson correlation coefficients between two assessments 8 weeks apart ranged from 0.71 for polyunsaturated fatty acids intake (when expressed as percentage of energy intake) up to 0.91 for energy intake. The reproducibility was found to be similar in males and females. Reproducibility was assessed for separate food items as well as for 20 food groups. Items consumed were often highly reproducible and rarely had a poor reproducibility. This food frequency questionnaire is considered to be a suitable tool to estimate and monitor the intake of fat, fatty acids and cholesterol in the Netherlands.

Validity of food intake measurement of adult Turkish immigrants in The Netherlands.

OBJECTIVE: To study the validity of the reported food intake in a study which was designed to assess exposure to dioxins from food sources. DESIGN: Repeated diet recalls were used to collect food intake data within a period of four months. Data on energy intake were related to computed basal metabolic rate (BMR). SETTING AND SUBJECTS: A group of 69 Turkish immigrants (30 men and 39 women aged 18-59 years) from two municipalities in the Eastern part of the Netherlands, whose selected basic socio-demographic characteristics reflect those of adult Turkish living in the Netherlands. RESULTS AND CONCLUSIONS: A mean energy intake (EI) to BMR ratio of 1.32 for women (mean EI = 8.1 MJ/day) and 1.36 for men (mean EI = 10.6 MJ/day) was found. Subjects in the lower and upper tertile of EI/BMR ratio differed only in body mass index (BMI: kg/m2). Pearson's correlation coefficient between EI/BMR and BMI was -0.39 (P < 0.05). The observed high prevalence of obesity in adult Turkish people complicates, as in other cultures, an accurate assessment of food intake.