Between- and within-subject variation in nutrient intake from infancy to old age: estimating the number of days required to rank dietary intakes with desired precision

Teaching subjects with type 2 diabetes how to incorporate sugar choices into their daily meal plan promotes dietary compliance and does not deteriorate metabolic profile

OBJECTIVE

To determine whether teaching free-living subjects with type 2 diabetes how to incorporate added sugars or sweets into their daily meal plan results in a greater consumption of calories (fat or sugar) and deteriorates their glycemic or lipid profiles but improves their perceived quality of life.

RESEARCH DESIGN AND METHODS

In an 8-month randomized controlled trial, 48 free-living subjects with type 2 diabetes were taught either a conventional (C) meal plan (no concentrated sweets) or one permitting as much as 10% of total energy as added sugars or sweets (S). Mean individual nutrient intake was determined using the average of six 24-h telephone recalls per 4 months. Metabolic control and quality of life were evaluated every 2 months. Quality of life was assessed using the Medical Outcome Survey and the Diabetes Quality of Life questionnaire.

RESULTS

The S group did not consume more calories (fat or sugar) and in fact ate significantly less carbohydrate (-15 vs. 10 g) and less starch (-7 vs. 8 g) and had a tendency to eat fewer calories (-77 vs. 81 kcal) than the C group. Weight remained stable, and there was no evidence that consuming more sugar worsened metabolic profile or improved their perceived quality of life.

CONCLUSIONS

Giving individuals with type 2 diabetes the freedom to include sugar in their daily meal plan had no negative impact on dietary habits or metabolic control. Health professionals can be reassured and encouraged to teach the new "sugar guidelines," because doing so may result in a more conscientious carbohydrate consumption.

Critical evaluation of energy intake using the Goldberg cut-off for energy intake:basal metabolic rate. A practical guide to its calculation, use and limitations

OBJECTIVES

To re-state the principles underlying the Goldberg cut-off for identifying under-reporters of energy intake, re-examine the physiological principles and update the values to be substituted into the equation for calculating the cut-off, and to examine its use and limitations.

RESULTS

New values are suggested for each element of the Goldberg equation. The physical activity level (PAL) for comparison with energy intake:basal metabolic rate (EI:BMR) should be selected to reflect the population under study; the PAL value of 1.55 x BMR is not necessarily the value of choice. The suggested value for average within-subject variation in energy intake is 23% (unchanged), but other sources of variation are increased in the light of new data. For within-subject variation in measured and estimated BMR, 4% and 8.5% respectively are suggested (previously 2.5% and 8%), and for total between-subject variation in PAL, the suggested value is 15% (previously 12.5%). The effect of these changes is to widen the confidence limits and reduce the sensitivity of the cut-off.

CONCLUSIONS

The Goldberg cut-off can be used to evaluate the mean population bias in reported energy intake, but information on the activity or lifestyle of the population is needed to choose a suitable PAL energy requirement for comparison. Sensitivity for identifying under-reporters at the individual level is limited. In epidemiological studies information on home, leisure and occupational activity is essential in order to assign subjects to low, medium or high PAL levels before calculating the cut-offs. In small studies, it is desirable to measure energy expenditure, or to calculate individual energy requirements, and to compare energy intake directly with energy expenditure.

Probabilistic modelling: theory and practice

Probabilistic modelling techniques allow much more realistic estimates of exposure and risk by computing the use of the full range of potential exposures rather than single 'worst case' exposures. However, these techniques require additional considerations regarding the appropriate data and models. This article reviews the theoretical aspects of probabilistic modelling and also considers some of the practical applications. The most common method, called Monte Carlo analysis, is discussed in some detail. The practical application of Monte Carlo to risk assessments is presented along with an evaluation of the input parameters. Topics also discussed include considerations of the requirements for precision and procedures for validation of assessments.

Adult female hip bone density reflects teenage sports-exercise patterns but not teenage calcium intake

OBJECTIVE

To examine how cumulative teenage sports histories and time-averaged teenage calcium intake are related to total body bone mineral gain between ages 12 and 18 years and to proximal femur bone mineral density (BMD) at age 18 years. Design. Longitudinal. Setting. University Hospital and local suburban community in Central Pennsylvania.

STUDY PARTICIPANTS

Eighty-one white females in the ongoing Penn State Young Women's Health Study.

OUTCOME MEASURES

Total body and proximal femur (hip) bone measurements by dual energy radiograph absorptiometry; nutrient intakes, including calcium, from 33 days of prospective food records collected at regular intervals between ages 12 and 18 years; and self-reported sports-exercise scores between ages 12 and 18 years.

RESULTS

Cumulative sports-exercise scores between ages 12 and 18 years were associated with hip BMD at age 18 years (r = .42) but were not related to total body bone mineral gain. Time-averaged daily calcium intake, which ranged from 500 to 1500 mg/day in this cohort was not associated with hip BMD at age 18 years, or with total body bone mineral gain at age 12 through 18 years.

CONCLUSIONS

The amount of physical activity that distinguishes a primarily sedentary teenager from one who engages in some form of exercise on a nearly daily basis is related to a significant increase in peak hip BMD.

Dietary intakes and nutrient status of vegetarian preschool children from a British national survey

BACKGROUND: Dietary intakes and nutrient status were compared in meat-eaters and non-meat-eaters from the National Diet and Nutrition Survey of children aged 1.5-4.5 years. METHODS: Children (n = 1351) were categorized as 'omnivores' or 'vegetarians', according to whether they consumed meat or meat products during a 4-day dietary record. Blood samples were also obtained for analysis of haematological and biochemical nutrient status. RESULTS: Three per cent of children were 'vegetarian'. They consumed higher proportions of milk and milk products, although this was significant only in older children (P = 0.007), owing to high consumption by the high proportion of Asian children. In vegetarians, energy intakes tended to be lower in both age groups. Percentage energy from protein and fat were lower, while that from carbohydrate was higher compared with omnivores. Cholesterol intakes were lower, significantly so for younger children (P < 0.001). Intakes of micronutrients were either higher (vitamins C and E, potassium) or lower (niacin and sodium) in younger vegetarians compared with omnivores. Energy-adjusted intakes of iron and zinc did not differ significantly from those of omnivores, although both intakes were low in many children (6-20% < LRNI), particularly in the younger group. Haematological and biochemical nutrient status indices showed few differences. Serum ferritin was lower in vegetarians, significantly so in younger children (P = 0.002). Antioxidant vitamin (A, C and E) status tended to be higher in vegetarians, while vitamin B12 intakes and status were more than adequate. Apart from poorer vitamin D intake and status in older Asian vegetarians, very few ethnic differences were observed. CONCLUSIONS: Nutrient intakes and status were generally adequate in preschool children who did not eat meat. Although serum ferritin levels were inferior (particularly in vegetarians under 3 years old), the lower intakes of fat, cholesterol and sodium, and higher antioxidant vitamin intakes and status indices were potentially beneficial. Given a balanced diet, adequate nutrient intakes and status can be maintained without consuming meat.

Validity of rapid estimates of household wealth and income for health surveys in rural Africa

STUDY OBJECTIVE

To test the validity of proxy measures of household wealth and income that can be readily implemented in health surveys in rural Africa.

DESIGN

Data are drawn from four different integrated household surveys. The assumptions underlying the choice of wealth proxy are described, and correlations with the true value are assessed in two different settings. The expenditure proxy is developed and then tested for replicability in two independent datasets representing the same population.

SETTING

Rural areas of Mali, Malawi, and Côte d'Ivoire (two national surveys).

PARTICIPANTS

Random sample of rural households in each setting (n=275, 707, 910, and 856, respectively).

MAIN RESULTS

In both Mali and Malawi, the wealth proxy correlated highly (r>/=0.74) with the more complex monetary value method. For rural areas of Côte d'Ivoire, it was possible to generate a list of just 10 expenditure items, the values of which when summed correlated highly with expenditures on all items combined (r=0.74, development dataset, r=0. 72, validation dataset). Total household expenditure is an accepted alternative to household income in developing country settings.

CONCLUSIONS

It is feasible to approximate both household wealth and expenditures in rural African settings without dramatically lengthening questionnaires that have a primary focus on health outcomes.

Measurement of dietary intake in children

When children and adolescents are the target population in dietary surveys many different respondent and observer considerations surface. The cognitive abilities required to self-report food intake include an adequately developed concept of time, a good memory and attention span, and a knowledge of the names of foods. From the age of 8 years there is a rapid increase in the ability of children to self-report food intake. However, while cognitive abilities should be fully developed by adolescence, issues of motivation and body image may hinder willingness to report. Ten validation studies of energy intake data have demonstrated that mis-reporting, usually in the direction of under-reporting, is likely. Patterns of under-reporting vary with age, and are influenced by weight status and the dietary survey method used. Furthermore, evidence for the existence of subject-specific responding in dietary assessment challenges the assumption that repeated measurements of dietary intake will eventually obtain valid data. Unfortunately, the ability to detect mis-reporters, by comparison with presumed energy requirements, is limited unless detailed activity information is available to allow the energy intake of each subject to be evaluated individually. In addition, high variability in nutrient intakes implies that, if intakes are valid, prolonged dietary recording will be required to rank children correctly for distribution analysis. Future research should focus on refining dietary survey methods to make them more sensitive to different ages and cognitive abilities. The development of improved techniques for identification of mis-reporters and investigation of the issue of differential reporting of foods should also be given priority.

Relationship between nutritional status and the glomerular filtration rate: results from the MDRD study

BACKGROUND

The relationship between the protein-energy nutritional status and renal function was assessed in 1785 clinically stable patients with moderate to advanced chronic renal failure who were evaluated during the baseline phase of the Modification of Diet in Renal Disease Study. Their mean +/- SD glomerular filtration rate (GFR) was 39.8 +/- 21.1 mL/min/1.73 m2.

METHODS

The GFR was determined by 121I-iothalamate clearance and was correlated with dietary and nutritional parameters estimated from diet records, biochemistry measurements, and anthropometry.

RESULTS

The following parameters correlated directly with the GFR in both men and women: dietary protein intake estimated from the urea nitrogen appearance, dietary protein and energy intake estimated from dietary diaries, serum albumin, transferrin, percentage body fat, skinfold thickness, and urine creatinine excretion. Serum total cholesterol, actual and relative body weights, body mass index, and arm muscle area also correlated with the GFR in men. The relationships generally persisted after statistically controlling for reported efforts to restrict diets. Compared with patients with GFR > 37 mL/min/1.73 m2, the means of several nutritional parameters were significantly lower for GFR between 21 and 37 mL/min/1.73 m2, and lower still for GFRs under 21 mL/min/1.73 m2. In multivariable regression analyses, the association of GFR with several of the anthropometric and biochemical nutritional parameters was either attenuated or eliminated completely after controlling for protein and energy intakes, which were themselves strongly associated with many of the nutritional parameters. On the other hand, few patients showed evidence for actual protein-energy malnutrition.

CONCLUSIONS

These cross-sectional findings suggest that in patients with chronic renal disease, dietary protein and energy intakes and serum and anthropometric measures of protein-energy nutritional status progressively decline as the GFR decreases. The reduced protein and energy intakes, as GFR falls, may contribute to the decline in many of the nutritional measures.

Estimation of population distributions of habitual nutrient intake based on a short-run weighed food diary

There have been many attempts to characterize day-to-day variation in nutrient intake. This variation has a fixed component, associated with particular days of the week, and a random component. Both components were studied for a range of nutrients, using 4 d weighed diary data from a large, nationally representative survey of people aged 65 years or over. Since day-to-day variation may distort the characterization of the population distribution of habitual nutrient intakes, especially when diets are studied over only a small number of days, a statistical method was developed to correct for this distortion. Results suggested that population distributions of habitual nutrient intake could be accurately constructed from 4 d weighed diary data and that the method might be successfully applied to studies based on as little as 2 d of observation. The method is particularly valuable for correcting estimates of extreme nutrient intakes for biases induced by uneven representation of days of the week and by within-person variation.

Dietary assessment of an educated young Spanish population using a self-administered meal-based food frequency questionnaire

In this study a self-administered meal-based semi-quantitative food frequency questionnaire was developed, whose main aim was to classify individuals by their intake of food groups and nutrients. The respondents (205 final participants) from the target population were recruited from students and staff of the Faculty of Chemistry of the University of Castilla-La Mancha in Ciudad Real (Spain). The validity of the questionnaire was assessed in comparison with a four-day weighed diet record on a subset group of participants (n = 38). Results of the calibration study were similar to those reported in the literature, showing a reasonable correlation between the two methods. To improve dietary habits of the target population, an effective nutritional education programme should stress the importance of increasing consumption of food groups rich in starch and reducing those containing high level of proteins, sugars, fat and cholesterol.

[Development of a quantitative questionnaire of food intake in japanese immigrants and their descendants residents in Sao Paulo, Brazil]

The present study describes the development of a questionnaire to assess usual frequency and quantity of food and nutrient intake by people of Japanese descent living in São Paulo, Brazil. Both the food list and appropriate serving sizes for food items from the Food Frequency Questionnaire (FFQ) were selected from a cross-sectional assessment of diet in a random sample of Japanese immigrants living in the city of São Paulo (first- and second-generations, n = 166), aged 45-70 years, using self-administered three-day food records. We used the food records to select food items on the basis of their contribution to total population intake of relevant foods and nutrients. Criteria for grouping separate foods included similarity in nutrient content per usual serving and the importance of a particular food (e.g., typical Japanese foods). Four portion sizes were presented: small, medium, large, and extra-large. We examined the frequency distribution of equivalent-gram weights of each selected food and identified the four serving sizes in the distribution. The quantitative FFQ was designed with 129 food groups and exact frequencies of intake. Instructions for self-reporting and applications of the method for epidemiological use are discussed.

Modeling the effects of maternal nutritional status and socioeconomic variables on the anthropometric and psychological indicators of Kenyan infants from age 0-6 months

This paper presents a comprehensive empirical analysis of the factors affecting growth and psychological development of over 100 infants from birth to age 6 months in the Embu region of Kenya. The analysis was divided into four parts. First, infants' birth weight, and length and head circumference as measured few days after birth, were modeled using multiple regression models. Maternal prepregnancy body mass index (BMI), gestation period, and parity were associated with infants' anthropometric measurements (P < 0.05). Second, the scores on seven clusters of the Brazelton Neonatal Behavioral Assessment Scale were explained by health and socioeconomic indicators. While the models had poor predictive power, the scores were comparable to those reported in the literature for Puerto Rican and African American infants. The third part of the analysis modeled infant growth between 1-6 months by analyzing longitudinal data on length, head circumference, and weight. Dynamic models were postulated for the effects of nutritional, socioeconomic, and environmental factors and morbidity on anthropometric variables. The results showed that infants' calcium intakes were positively associated with length (P < 0.05). Maternal BMI and hemoglobin concentration were positively associated with infant weight (P < 0. 05); infant morbidity was negatively associated with weight (P < 0. 05). Lastly, the infants' scores at 6 months on the Bayley Motor Scale and on eight items from the Bayley Infant Behavior Record were explained using anthropometric, socioeconomic, and psychological variables. The infants' arm circumference and intake of protein were significant predictors of scores on the Bayley Motor Scale. In addition, time spent by the mother talking to the infant was positively associated with the scores on the Bayley Infant Behavior Record. The empirical results have implications for identifying vulnerable children in developing countries.

Dependence of dietary intake estimates on the time frame of assessment

Food chemical risk management needs, among other things, assessment of exposure. For dietary intake food consumption surveys are the data source to be used. One complicating factor in the usage of these data is the dependence of dietary intake estimates on the time frame of assessment. Central to this time dependence is the within-subject variation regarding the usage of food products and, as a consequence, the intake of chemicals. Within-subject variation is mostly as large as or larger than between-subject variation. Expressed per kilogram body weight, average (total) variation in intake variables depends on the age group, with variation usually being greater at younger age, most likely as a result of the higher intake levels at that age. Combination of age groups results in an increase in between-subject variation, and correction based on the figures for the total population will be too small. Ideally, exposure data for all days of one's life should be available to assess lifetime exposure. Since information on all these days is not an attainable and practical option, and not an option to strive for either, the most recent available data should be used that can be extended with simulation studies to anticipate future developments. The present food consumption surveys available in European countries are based on data that vary from 1 day (24-h recall and dietary record) to habitual intake (dietary history and food frequency). The data of a survey based on 1 day refer to 0.004% of an average lifetime of 70 years. Based on the demographic picture of the population, a reasonable approximation of lifetime intake can be obtained. The proportion of users and the consumption level among users depend on the time frame of assessment, especially for irregularly consumed products. Usage of the concept of "users only" overestimates lifetime exposure of the population, the extent of overestimation depending on the duration of the survey. The likelihood that all consumers have been exposed to a chemical once during a lifetime period is realistic in the sense of the best approximation of reality. As a result of this assumption all exposure assessments will have a similar point of departure and the dependence of the results on the food consumption method will be reduced.

Reproducibility and validity of a food frequency questionnaire among fourth to seventh grade inner-city school children: implications of age and day-to-day variation in dietary intake

OBJECTIVE

To assess the reproducibility and validity of a semiquantitative food frequency questionnaire (FFQ) to classify children and adolescents in terms of daily servings of fruits and vegetables and intake of calories, protein, fat, carbohydrate, dietary fibre, vitamin C, phosphorous, calcium and iron.

DESIGN

FFQs were collected in the autumn of 1993 and 1994. Four 24-hour diet recalls were collected during the same 1-year period and their mean was compared to the FFQ diet estimates.

SETTING

Low income, inner-city state schools.

SUBJECTS

A sample of 109 inner-city fourth to seventh grade students.

RESULTS

The 1-year reproducibility of the FFQ, assessed with Spearman correlations, was lower among the fourth and fifth (range: r=-0.26 to 0.40) than the sixth and seventh grade students (range: r=0.18-0.47). After adjusting for day-to-day variation in dietary intake, for most nutrients and foods the correlations between the FFQ and the 24-hour recalls remained greater among the junior high school students (fourth to fifth grade range: r=0.0-0.42; sixth to seventh grade range: r=0.07-0.76).

CONCLUSIONS

Inner-city sixth and seventh grade students demonstrated the ability to provide valid estimates of intake of calories, carbohydrate, calcium, phosphorous, iron and vitamin C over the past year. However, children in the fourth and fifth grades experienced some difficulty in completing the FFQ. Our results suggest that, before using this instrument with fourth and fifth grade children, investigators should assess whether study participants can think abstractly and are familiar with the concept of 'average intake'.

Validity and reproducibility of a food frequency interview in a Multi-Cultural Epidemiology Study

PURPOSE

There is limited support for the validity and reproducibility of dietary assessment in culturally diverse populations. The goal of this study was to evaluate the comparative validity and reproducibility of a Food Frequency Questionnaire (FFQ) used in the observational, multi-cultural Insulin Resistance Atherosclerosis Study (IRAS).

METHODS

Women (n = 186) were approximately equally distributed by ethnicity from one urban center (African Americans and non-Hispanic whites) and one rural center (Hispanics and non-Hispanic whites). The IRAS FFQ was modified from the National Cancer Institute Health Habits and History Questionnaire to include ethnic and regional foods. Validity was assessed by comparing dietary values, including supplements, obtained from the FFQ to the average intake estimated from a series of 8 24-hour dietary recalls collected by telephone over the same 1-year period. Reproducibility was assessed among women who reported no change in their usual diet (n = 133) by comparing data from the original IRAS FFQ (in-person) with the FFQ administered for the validity study (two to four years later, by telephone).

RESULTS

Correlation coefficients for validity were statistically significant for most nutrients (mean r = 0.62 urban non-Hispanic white, 0.61 rural non-Hispanic whites, 0.50 African American, 0.41 Hispanic) and did not differ among subgroups of obesity or diabetes status. The median correlation coefficient for the total sample was 0.49. Correlations were lower for women with less than 12 years of education (mean r = 0.30; median r = 0.25). The lower correlations among Hispanics was largely explained by the lower educational attainment in that sample. For reproducibility, the mean correlation for nutrients evaluated was r = 0.62 (median r = 0.63) and did not differ for subgroups.

CONCLUSIONS

Although educational attainment must be considered, the IRAS FFQ appears to be reasonably valid and reliable in a diverse cohort.

Preventive nutritional factors in epidemiology: interaction between sodium and calcium

1. It is generally believed, though difficult to prove, that diet plays a role in the risk of various diseases. Components of difficulties include several issues such as dietary assessment method, regression dilution bias, multicolinearity and interaction among nutrients. 2. The present study focuses on colinearity and interaction between sodium and calcium, which should be cautiously examined in nutritional epidemiological studies in relation to blood pressure and bone mineral density. 3. The World Health Organization's International Cooperative Cardiovascular Diseases and Alimentary Comparison study showed significant multicolinearity among urinary sodium, calcium and urea nitrogen as well as urinary calcium and magnesium. Urinary sodium and calcium had significant correlation (r = 0.438, P < 0.05, n = 48) by cross-centre analysis. 4. Interaction between sodium and calcium on bone mineral density is studied using the data set from bone mineral density screening for 1658 females, aged 20-40 years, in Yokohama, Japan. Among those who have lower calcium intake (< 600 mg/day), higher calcium intake (%) from small fish, which is likely to be associated with a high salt diet, related to significantly lower mineral bone density. 5. Interaction between sodium and calcium on bone mineral density among young Japanese females is suggested. Moderate sodium restriction is needed for prevention of not only cardiovascular diseases but also osteoporosis.

Areas of fat loss in overweight young females following an 8-week period of energy intake reduction

In order to investigate the main areas of fat loss after an 8-week period of energy intake reduction, the distribution of body fat was assessed on 14 females (BMI 27.3+/-0.83 kgm(-2)) (mean +/- SEM), aged 18-22 years. Total body fat was determined by hydrostatic weighing and subcutaneous fat mass and distribution were assessed using ultrasound and waist-hip circumference ratios prior to, and following, an 8-week period during which subjects attempted to reduce their energy intake by about 4.2 MJ day(-1). Subjects lost an average of 2.99+/-0.34 kg (p < 0.001), with greater loss (p < 0.001) of internal fat (1.5+/-0.2 kg) than of subcutaneous fat (0.7+/-0.1). Subjects reduced their waist-hip ratio from 0.771+/-0.01 to 0.762+/-0.01 (p < 0.01), their waist circumference from 807+/-24 to 790+/-23 mm (p < 0.001) and their hip circumference from 1047+/-29 to 1037+/-29 mm (p < 0.001). Those with an android distribution of fat (n = 5) lost more weight than those with gynoid distribution (n = 9) (3.80+/-0.38 kg vs 2.54+/-0.14 kg, p < 0.05); they also showed a greater decrease in waist circumference (27+/-5 vs 14+/-4 mm, p < 0.05) and a greater loss from internal fat stores (2.1+/-0.3 kg vs 1.1+/-0.2 kg, p < 0.05). The findings suggest that individuals are prone to lose internal fat during a short period of reduced energy intake. As the visceral fat store is the largest internal fat depot in the body, this suggests that individuals are indeed losing fat that could predispose to upper body obesity.

The prevalence of diabetes and associated coronary risk factors in urban and rural older Mexican populations

OBJECTIVE

To determine the prevalence of diabetes and examine its association with food intake, anthropometric and metabolic variables, and other coronary risk factors in urban and rural older Mexican populations.

DESIGN

A cross-sectional study.

SETTING

Three Mexican communities (urban areas of medium and low income and a rural area).

PARTICIPANTS

A total of 121 men and 223 women aged 60 years and older and 93 men and 180 women aged 35 to 59 years were selected randomly for inclusion in the survey, which was derived from the CRONOS study (Cross-Cultural Research on Nutrition in the Older Adult Study Group) promoted by the European Economic Community.

MEASUREMENTS

A personal interview assessed demographic information, personal medical history, and functional status, and a 24-hour diet recall was obtained. A physical examination included anthropometric and blood pressure measurements. A fasting blood sample was obtained for measurements of lipids, insulin, and glucose.

RESULTS

Diabetes prevalence was higher in men than in women for all age groups: 16.7% versus 9.5% in younger adults and 30.8% versus 22.8% in older adults. For all age groups, diabetes was more highly prevalent in urban communities. Using a multivariate stepwise logistic regression, variables associated independently with diabetes in older individuals were: gender (male sex: OR = 2.1; P < .009); diminished carbohydrate intake in the diet (OR = 0.77; P < .03); central distribution of adiposity (OR = 1.9; P < .03); and functional disability (OR = 2.3; P < .01). This relationship was not observed with living area, income, education, fiber and alcohol intake, body mass index, or age. Individuals 80 years and older had a diminished atherogenic risk profile. Diabetes in older people was associated significantly with hypertriglyceridemia, impaired functional status, and an increased prevalence of ischemic heart disease; in younger adults diabetes was associated with low density lipoprotein (LDL) hypercholesterolemia, hypertriglyceridemia, and a proportionally higher fat intake.

CONCLUSION

This survey confirms the high prevalence of diabetes in the older Mexican population - particularly in men and in individuals living in urban areas - associated with an increased prevalence of other coronary risk factors. Diabetes was associated with higher fat, low carbohydrate, low fiber diets and increased prevalence of central distribution of adiposity. In the older subjects, diabetes was associated significantly with hypertriglyceridemia, impaired functional status, and increased prevalence of ischemic heart disease. A bias produced by early mortality and a survivorship effect must be considered in studies of older individuals. The health situation in the older Mexican population presents a complex problem that needs correct diagnosis and better strategies to benefit those segments of the population at increased risk.

Nutritional factors in cancer prevention

Current epidemiologic and laboratory evidence suggests that nutritional factors may play an important role in chemoprevention, although the relative importance of that role for the various micronutrients and dietary constituents is still unclear. The complexity of this area of investigation and practice clearly requires knowledge of the relevant measurement tools, chemistry, biology, and food science, and also the limitations that must be considered in the interpretation of nutritional data. Despite the challenges encountered in translation to clinical research and practice, nutrition remains a promising area of chemoprevention, likely to yield important information and strategies with a large public health impact.

Magnitude, determinants and impact of under-reporting of energy intake in a cohort study in Greece

OBJECTIVES

To investigate the frequency and the determinants of under-reporting in a semi-quantitative food frequency questionnaire used in the Greek segment of the European Prospective Study on Nutrition, Cancer and Health (EPIC study).

DESIGN

A food frequency questionnaire was completed by 9262 adult men and women. The questions included in this questionnaire covered the average intake of approximately 150 food items and beverages over 1 year. Evaluation of under-reporting was conducted on an individual basis taking into account the expected daily variation of nutritional intakes during the time period of recording. Individuals whose energy intake was lower than 1.14*BMR (basal metabolic rate) were defined as under-reporters.

SETTING

Urban and rural population of Greece.

RESULTS

The data indicated underestimation of energy intake by 11.8% of individuals enrolled. Results from a logistic regression model indicated that body mass index (BMI), gender, age and educational level were significant predictors of under-reporting. The proportion of overweight participants (BMI >30) who tend to under-report energy intake was more than twice that of normal-weight individuals. Men were significantly more prone to under-reporting compared to women, while low education individuals under-report more often than others. Exclusion of under-reporters generated, as expected, mean nutrient values that were significantly higher (by about 6%) than those derived from the total number of participants. When the nutrient values were energy-adjusted, however, or were expressed as percentages of energy intake for macronutrients or as nutrient densities for micronutrients, the emerging differences were minimal and generally statistically not significant.

CONCLUSIONS

Under-reporting does exist and it is more extensive among men, those with low education levels and the overweight participants. Adjustment for energy intake minimizes the bias generated by under-reporting with respect to particular nutrients and their association with various disease outcomes in the cohort.

Demographic and socioeconomic determinants of variation in food and nutrient intake in an Andean community

Understanding the sources of variation in a community's diet is vital for development work, as well as being a source of anthropological and cultural insights. Previous surveys in the South American Andes suggest that nutrient deficiencies may be widespread; however, such interpretations have remained tentative since variance in Andean populations' diet has not been thoroughly examined. In this paper we consider the variation in diet due to variation in age, sex, and socioeconomic status and variation attributed to inter- and intraindividual variation in the diet. One to six days of dietary data (mean = 3.1) were collected via 24 h recalls from 221 residents of a small, rural community in highland Ecuador. The contribution of various food groups to the diet varied with land holdings and age but not sex. For example, animal-derived foods contribute more and tubers contribute less to the diet of the households with > or = 5 Ha, and sweets contribute more to the diet of children. The interindividual variation in energy and nutrient intake was low and the intraindividual variation high relative to developed countries. The consequence are twofold. First, because interindividual variability is low, group mean intake can be estimated relatively easily, facilitating group comparisons. Second, because intraindividual variation is high, individual nutrient intake cannot be easily estimated, which will decrease the ability to detect associations between nutrient intake and health measures. This knowledge of the sources of dietary variation can lead to better study and survey designs in the rural Andes and elsewhere in the developing world.

Reproducibility and validity of a food frequency questionnaire in European and Polynesian New Zealanders

The reproducibility and validity of a self-administered 142-item food-frequency questionnaire (FFQ) was assessed in a population comprising 124 European and 52 Polynesian (17 Maori and 35 Pacific Island) New Zealanders aged 40-65 years. Reproducibility correlation coefficients, determined by administration of the same questionnaire on two occasions 3 years apart, were higher in European than Maori and Pacific Island participants, ranging from 0.47 to 0.87 in Europeans (median 0.66) and from 0.41 to 0.79 in Maori and Pacific Island people (median 0.44). In general, there were no significant differences in mean nutrient intakes calculated from the two FFQs by Europeans or Maori and Pacific Island participants despite their cultural and language differences. When the FFQ was compared with a 3-day food diary in a subsample of 101 Europeans, 15 Maori and 22 Pacific Islanders, the validity was good for most nutrients, with overestimation of a few nutrients in each ethnic group. Correlation coefficients between the 3-day food diary and FFQ ranged from 0.41 to 0.81 in Europeans (median 0.48) and from 0.36 to 0.56 in Maori and Pacific Island people (median 0.55). Ratios of energy intake to resting metabolic rate suggested that Maori and Pacific Island people were more likely to underestimate their habitual energy intake by the 3-day diet diary method compared to Europeans, but that Europeans were more likely to underestimate total energy intake by the food frequency method and Pacific Island participants to overestimate it. Obese Europeans and Maori were more likely to under-report dietary intakes by the 3-day diary method. We conclude that our FFQ performed better in European than Maori and Pacific Island participants.

Antioxidant status and lipid peroxidation in diabetic pregnancy

Pregnancy in insulin-dependent diabetes mellitus is associated with a greater incidence of fetal abnormality. Animal studies suggest that increased free-radical production and antioxidant depletion may contribute to this risk. The aim of the present study was, therefore, to assess nutritional antioxidant status and lipid peroxidation in diabetic mothers in comparison with a control group. A 7 d dietary history and a food-frequency questionnaire were performed and venous blood collected for biochemical analyses from thirty-eight diabetic mothers and matched control subjects before 12 weeks gestation. Protein intake was significantly greater in diabetic patients (81.4 (SE 14.8) v. 72.7 (SE 15.8) g/d, P = 0.015), while total sugar intake was less (79.5 (SE 13.2) v. 104.8 (SE 28.8) g/d, P < 0.001). There were no significant differences in the intake of the major antioxidant vitamins (retinol, vitamin C or vitamin E) or beta-carotene. However, intakes of a number of other micronutrients (including Se, Zn, Mg, Mn, riboflavin, thiamin, niacin and folate) were greater in diabetic patients. Among the nutritional chain-breaking antioxidants, serum levels of alpha-tocopherol (21.6 (SE 5.7) v. 17.3 (SE 4.7) mumol/, P = 0.0013), beta-carotene (0.27 (SE 0.18) v. 0.14 (SE 0.11) mumol/l, P = 0.003) and lycopene (0.23 (SE 0.17) v. 0.16 (SE 0.13) mumol/l, P = 0.03) were greater in diabetic patients. There was no evidence of greater lipid peroxidation in diabetic patients, and total antioxidant capacity was similar in the two groups. Overall, these results indicate that nutritional antioxidant status is better in this group of diabetic mothers than in control pregnant non-diabetic subjects attending the same maternity hospital.

Variability in PAH-DNA adduct measurements in peripheral mononuclear cells: implications for quantitative cancer risk assessment

Biomarkers such as DNA adducts have significant potential to improve quantitative risk assessment by characterizing individual differences in metabolism of genotoxins and DNA repair and accounting for some of the factors that could affect interindividual variation in cancer risk. Inherent uncertainty in laboratory measurements and within-person variability of DNA adduct levels over time are putatively unrelated to cancer risk and should be subtracted from observed variation to better estimate interindividual variability of response to carcinogen exposure. A total of 41 volunteers, both smokers and nonsmokers, were asked to provide a peripheral blood sample every 3 weeks for several months in order to specifically assess intraindividual variability of polycyclic aromatic hydrocarbon (PAH)-DNA adduct levels. The intraindividual variance in PAH-DNA adduct levels, together with measurement uncertainty (laboratory variability and unaccounted for differences in exposure), constituted roughly 30% of the overall variance. An estimated 70% of the total variance was contributed by interindividual variability and is probably representative of the true biologic variability of response to carcinogenic exposure in lymphocytes. The estimated interindividual variability in DNA damage after subtracting intraindividual variability and measurement uncertainty was 24-fold. Inter-individual variance was higher (52-fold) in persons who constitutively lack the Glutathione S-Transferase M1 (GSTM1) gene which is important in the detoxification pathway of PAH. Risk assessment models that do not consider the variability of susceptibility to DNA damage following carcinogen exposure may underestimate risks to the general population, especially for those people who are most vulnerable.

Interpreting epidemiologic studies of diet-disease relationships

The purpose of this paper is to examine key issues in the interpretation of nutritional epidemiologic study results when the focus is on major chronic degenerative diseases of multifactorial etiology. The estimation of disease risk associated with a particular dietary factor is influenced by the presence of other risk factors within the study population, complicating the interpretation of relative risk and odds ratio estimates in this context. Identifying the precise role(s) that dietary factors play in the onset or progression of chronic diseases is further complicated by the intercorrelation of dietary components and by the correlation of dietary patterns with other behavioral and environmental factors which may also impart or exacerbate risk of disease. Issues of study design and measurement make it difficult to identify relationships in nutritional epidemiology, but also thwart the rejection of hypotheses regarding diet-disease relationships when studies fail to yield significant associations. In drawing causal inferences from epidemiologic findings, it is important to examine evidence from a variety of sources and to look for congruence between epidemiologic, clinical and laboratory research findings.

Development and testing of a seven-day dietary recall. Dietary Assessment Working Group of the Worcester Area Trial for Counseling in Hyperlipidemia (WATCH)

Using multiple 24-hr recalls (24HR) we tested the Seven Day Dietary Recall (7DDR) developed to assess nutrient exposures, especially lipids, in dietary interventions and other clinical trials requiring measurement of effect over moderate time periods. A total of 261 individuals in three studies completed a 7DDR at the end of a 3- to 5-week period during which 3 to 7 24HR were telephone-administered on randomly selected days. One of these studies and data from one additional study (total n = 678) allowed us to test the ability of the 7DDR to predict serum lipid changes in an intervention setting. In correlation and linear regression analyses, high levels of agreement between 7DDR and 24HR were obtained. For total energy: r = 0.67 and b = 0.69, and for total fat intake (g/day): r = 0.67 and b = 0.80. When 7 days of 24HR were available agreement tended to be higher. For total energy: r = 0.69 and b = 0.95, and for total fat (g/day): r = 0.71 and b = 1.04. Data derived from the 7DDR and fit to the Keys and Hegsted equations closely predicted actual changes in total serum cholesterol (within 15% and 10%, respectively). The 7DDR is a relatively easily administered, sensitive method to assess short-term changes in dietary fat consumption in individuals.

Magnesium, calcium and phosphorus contents in daily food rations in primary school children: questionnaire and analytic studies

Aims of the performed studies included working out a technique of determining representative rations on the basis of questionnaire studies on school children in Wielkopolska west region of Poland. The reconstructed representative daily food rations provided grounds for analytic studies. The studies were performed in the four seasons of the year. The studied food rations failed to cover the recommended daily intake of Mg and Ca. On the other hand, the daily intake of P transgressed the food norms. The inadequate Ca to Mg and Ca to P ratios were interpreted as deserving special concern when confronted with the market situation in Poland and as creating particular health hazards for the studied school children. The employed statistical analysis demonstrated that the suggested technique of determining representative rations may be employed in evaluation of Mg, Ca and P intake.

Nutrient density estimates from an average of food frequency and food records correlate well with serum concentration of vitamins E and the carotenoids in free-living adults

Dietary intakes are usually estimated by either a food frequency test, or by food records. We hypothesized that dietary intake estimates for fat soluble vitamins might be more accurate if information from both food frequency tests and food records were used. We estimated dietary intakes in 10 healthy adults by 4 food frequency questionnaires and ten 3-day food records collected over a year. Serum antioxidant nutrient concentrations (vitamins A, E, and the carotenoids) were measured by HPLC throughout the year. Few changes in intake occurred over the year. Estimates of nutrient densities correlated more often than estimates of nutrient intakes to serum nutrient concentrations. Nutrient density estimates derived from the average of food frequency and food record estimates were significantly correlated with serum nutrient concentrations more often than dietary estimates derived from either food frequency or food records alone. We suggest that nutrient density estimates derived from a combination of food frequency and food records may be useful for studies of free-living individuals.

Physical activity levels from a meta-analysis of doubly labeled water studies for validating energy intake as measured by dietary assessment

Studies using doubly labeled water have identified underreporting of food intake as a problem of dietary surveys. However, reported energy intakes may be evaluated by comparison with energy requirements expressed as multiples of the basal metabolic rate, and a formula for calculating the value below which reported intake cannot be either a valid measure of habitual intake or a true low intake obtained by chance is presented. The energy requirements of different age-sex groups needed for the comparison with energy intakes have been obtained from a meta-analysis of doubly labeled water data.

Evaluation of the effect of the use of vitamin supplements on vitamin A intake among (potentially) pregnant women in relation to the consumption of liver and liver products

OBJECTIVE

To assess the distribution of dietary vitamin A intake among Dutch women aged 16-50 and among pregnant women, and to evaluate the effect of the use of a vitamin A (1200 RE) containing multivitamin supplement in terms of nutritional and teratogenic risk.

STUDY DESIGN

Data from the 2nd Dutch national food consumption survey (1992) were used for calculation of the vitamin A intake among 1725 16-50 year old women and 58 pregnant women. Calculations were performed with and without simulation of the use of a supplement containing 1200 RE vitamin A.

RESULTS

Average vitamin A intake, based on a two-day dietary record method, compared quite well with recommended intake levels: 850 RE for the 16-50 year old non-pregnant (NP) women (RDA: 800 RE), and 990 RE for the pregnant (P) women (RDA: 1000 RE), respectively. The use of liver on one of the days under survey resulted in high intakes: 60% of the women in this subgroup exceeded the 'safe upper intake limit' of 3000 RE, while in 23% of the cases intakes were > 7500 RE. Those not consuming liver or liver products on the days under survey had relatively low average intakes [NP (n = 1472): 540 RE; P (n = 46): 720 RE]; about 70% of the non-liver users had intakes below the RDA. Including the daily use of a vitamin A containing multivitamin supplement with 1200 RE resulted in intakes > RDA, while only in 2% (NP), respectively 3% (P) of the cases the 'total' intake exceeded the 3000 RE level, but remained in all cases below 7500 RE/day. serving per day.

CONCLUSION

The use of a vitamin A containing (maximum 1200 RE) multivitamin supplement can contribute to a controlled and adequate vitamin A intake and be considered as safe for pregnant women or women who wish to become pregnant, if the consumption of liver is completely avoided and the consumption of liver products is limited to maximum one.

Possible use of food consumption surveys to estimate exposure to additives

Several methods can be and are being used to assess individual food consumption. Four types, namely 24-h recall, dietary records, food frequency and dietary history are discussed. For assessing the exposure to additives it is concluded that the dietary history method is probably the best choice since this method is oriented towards a quantification of habitual food consumption. Dietary records and 24-h recall can be used as long as their short-term nature is accounted for. High intake levels obtained by those methods are in a way a worst-case analysis, especially when the calculations are based on users only. Since children have, on average, a higher consumption per kg of body weight and acceptable daily intakes (ADIs) are based on body weight, this group must be of special importance in risk assessment regarding additives. However, a relatively high intake among (young) children is an age effect and ADIs refer to lifetime exposure. Both food consumption and additive use in food products are changing over time, so that existing databases are prone to becoming outdated relatively fast. At the end of this paper an overview is given of existing databanks in the EU in relation to the estimation of exposure to additives.

Reproducibility and validity of a food frequency questionnaire in a case-control study on breast cancer

A 110-item food frequency questionnaire was tested among 152 community controls of the Kuopio Breast Cancer Study. They completed the questionnaire twice and kept two 7-day diet records at 3-month intervals. The intraclass correlations for nutrients varied from 0.49 (thiamine with supplements) to 0.81 (lactose), and for foods from 0.52 (poultry) to 0.84 (alcoholic drinks). The Pearson correlations between the first food frequency questionnaire and the 14-day diet records, after adjustment for energy, varied for nutrients from 0.18 (thiamine without supplements) to 0.80 (alcohol), and for foods from 0.30 (inner organs) to 0.90 (coffee). Comparison of quintile classification between the two methods is reasonably accurate when observed restrictions concerning some nutrients and foods are taken into account. A low association (r = 0.12) was observed between toenail selenium and dietary selenium intake, indicating the difficulty of estimating selenium intake in the Finnish diet.

The tracking of nutrient intake in young children: the Framingham Children's Study

OBJECTIVES

This study compared the nutrient intake of children at 3 through 4 years of age with that in subsequent years to determine whether nutrient intake tracked over time.

METHODS

Intakes of 10 nutrients were estimated by means of multiple days of food diaries collected over a span of up to 6 years of follow-up for 95 children in the Framingham Children's Study. All diaries collected during each of three age periods (age 3 through 4, age 5 through 6, and age 7 through 8) were averaged. Nutrient density intakes at each age period were compared.

RESULTS

Nutrient-specific correlations ranged from .37 to .63 between nutrient density intakes at age 3-4 and age 5-6. Correlations between intakes at age 3-4 and age 7-8 ranged from .35 to .62. Consistency of classification was strong; 35.7% to 57.1% of children in the highest quintile of intake at age 3-4 remained in that quintile at age 5-6, and 57.1% to 85.7% remained in the top two quintiles. At age 7-8, 40.0% to 66.7% of those with the highest intake at baseline were still in the top quintile, and 60.0% to 93.3% remained in the top two quintiles. Results were similar in the lowest quintile of intake. Extreme misclassification was rare.

CONCLUSIONS

This study suggests that tracking of nutrient intake begins as young as 3-4 years of age.

Nutrient intake and biochemical status of non-instutionalized elderly subjects in Norwich: comparison with younger adults and adolescents from the same general community

The Department of Health (1992) has recently stated that 'Nutritional reviews concerning elderly people are especially constrained by lack of data', and that much of the emphasis in the nutritional literature has been placed on the study of institutionalized, and often chronically ill, elderly subjects rather than the non-institutionalized elderly who form the majority of this population. The present study presents information on the dietary intake and biochemical status of non-institutionalized elderly subjects (68-73 and 74-90 years) and compares such data with those obtained for adult (20-64 years) and adolescent (13-14 years) populations living within the same community. Nutrient intakes and appropriate biochemical measurements of nutrient status, performed on fasting blood samples, were statistically examined and have been discussed in relation to potential age-related influences. The nutrient intake of elderly subjects was on a par with adolescents of corresponding sex but generally lower than that of adult counterparts. There were several significant differences in biochemical measurements of nutrient status between age groups. In general these did not suggest progressive age-related trends. However, there were significant suggestions of age-related increases in whole-blood glutathione peroxidase (EC 1.11.1.9) activity, serum ferritin, plasma cholesterol, LDL and triacylglycerol concentrations and decreases in plasma HDL and ascorbic acid concentrations. The significance of these differences is discussed. An age-related difference (suggestive of a decline) in vitamin C status together with a difference (suggestive of an increase) in glutathione peroxidase activity may indicate an imbalance in the regulation of O2-derived free-radicals with ageing. These observations are worthy of a further study in the light of current thinking which relates the induction of a number of diseases to oxidative damage.

Comparison between fat intake assessed by a 3-day food record and phospholipid fatty acid composition of red blood cells: results from the Monitoring of Cardiovascular Disease-Lille Study

We investigated the relationship between assessment of fatty acid intake by a 3-day food record and by capillary gas chromatography of erythrocyte phospholipid fatty acid. The study was performed in a sample of 244 men aged 45 to 66 years from the general population who were participating in the Monitoring of Cardiovascular Disease (MONICA)-Lille survey. The relationship between each nutrient and food item and erythrocyte phospholipid fatty acid was investigated by a regression model on proportion including each food item and nutrient as a dependent variable and percentage of fatty acid and covariables (nonalcoholic energy intake, age, alcohol intake, and smoking) as independent variables. Polyunsaturated fat and linoleic acid intake were positively correlated with linoleic acid content of erythrocytes (beta = 0.641 and 0.604, respectively, P < .001). Monounsaturated and saturated fat intake were correlated with oleic acid (beta = 0.375 and 0.373, respectively, P < .01). Fish intake correlated positively with docosahexaenoic acid (DHA) (beta = 0.383, P < .001) and negatively with arachidonic acid (beta = -0.509, P < .01). These data confirm, on a group level, a good relationship between assessment of polyunsaturated fat intake by a 3-day record and linoleic acid content of erythrocyte membranes. These data suggest that erythrocyte oleic acid content is a marker of both saturated and monounsaturated fat intake.

Reproducibility and validity of a food-frequency questionnaire designed for use in girls age 7 to 12 years

This study focused on a food-frequency questionnaire (FFQ) designed to measure nutrient intake in girls aged 7 to 12 years, inclusive. The instrument's reproducibility and validity were assessed using food records (FRs) as gold standards of measurement. Log-transformed nutrient intake estimates were compared from two FFQs and between FFQs and FRs. Intraclass correlation coefficients measuring the reproducibility of the FFQ ranged from 0.11 (starch) to 0.69 (fiber). Intraclass correlation coefficients measuring agreement between FFQ and 14l-day FR data varied between 0.15 (starch) and 0.68 (vitamin B2) for the first, and between 0.06 (starch) and 0.95 (vitamin B1) for the second FFQ. FFQs were in the best agreement with FRs for the following nutrients: fiber, vitamin B1, vitamin B2, vitamin C, and beta-carotene. Joint classifications revealed that overall, 36% of subjects were similarly categorized by FFQ and FR, and 70% of those in the lowest or highest FR quartiles were were found in the lowest or highest FR quartiles were found in the lowest or highest two FFQ quartiles, respectively.

Predictors of dietary intake in a functionally dependent elderly population in the community

OBJECTIVES

The aim of this study was to describe dietary intake and identify predictors of energy and protein intake in a group of high-risk elderly people.

METHODS

All elderly persons receiving publicly financed home care services in the area of Sherbrooke, Quebec, Canada, were eligible. Subjects (n = 145) 60 to 94 years of age from three home care programs were interviewed to measure sociodemographic, health, and food-related behavior variables. Three nonconsecutive 24-hour recalls were used to describe usual dietary intake. Independent predictors of energy and protein intake were derived from multiple regression analyses.

RESULTS

Very low mean energy intakes were observed in this functionally dependent population. More than 50% of the study subjects did not meet the recommended levels of daily protein intake (0.8 g/kg body weight). Significant independent determinants of intake were burden of disease, stress, poor appetite, and vision.

CONCLUSIONS

Results suggest that community-living elderly people with loss of autonomy may have more nutritional problems than healthy elderly individuals. Surveillance of predictors of dietary intake may enable early detection and prevention of nutritional deficits.

Dietary assessment of a group of elderly Spanish people

The dietary patterns of 60 elderly from Spain (37 women and 23 men) were examined by analysis of the food, energy and nutrient intake during 5 days. The caloric profile was somewhat unbalanced, since the percentage of total energy intake from proteins and lipids was above the recommended limit whereas the proportion of energy derived from carbohydrates was slightly deficient. The degree of underreporting derived by subtracting predicted total daily energy expenditure from self-reported energy intake obtained from a diet control during 5 days is 120 kcal/day in men and 334 kcal/day in women. More than 50% of the population showed intakes of pyridoxine, folates, vitamin A (only in men), vitamin D, vitamin E. zinc, magnesium and iron (only in women) lower than those recommended. Although it is likely that the real intakes of these micronutrients are higher than the levels measured considering the underreporting, the obtained results show the existence of a risk of deficiency of several nutrients. An increase in the energy intake of the group with a parallel increase in physical activity with a view to avoiding weight gain may be of use in improving the nutritional status of the group. This measure, together with increased consumption of vegetables and milk products especially, may lead to a striking reduction in illness, a finding that is of considerable clinical and public health importance.

Determination of intra- and inter-individual variability and its effect on the number of days required to assess the usual intake of a 1-year-old infant population

Diet variability influences the accuracy of the assessment of the relationship between nutrient intake and disease. The present study investigates intra- and inter-individual variability in an infant population at 12 months. The mothers of 79 infants completed a 7-day weighted food record. No significant difference in nutrient intake was observed between males and females. For some nutrients an intra-/inter-individual variability ratio > 1 was found. Adjustment for total calorie intake slightly altered the intra-/inter-individual variability ratio of many nutrients. An error margin of 10% or less for calories can be expected within an 18-day study. Most nutrients however would need to be studied for over 30 days to give an error margin < or = 10%. For dietary cholesterol, vitamins A, B6, C, and E, bracketing the error within the 10% margin would require an unrealistic time frame. Adjustments for calorie intake reduced the number of days in the dietary record for some nutrients. A lower intra/inter-individual variability ratio was seen when data for adults and older infants were compared.

Walking at work and bone mineral density of premenopausal women

The objective of this cross-sectional study was to determine whether habitual physical activity such as daily walking at work affects bone mineral density (BMD) in healthy premenopausal women. Thirty-one letter or newspaper carriers and 30 sedentary (non-exercising) office workers were screened out from 167 subjects working in the public post office and a private newspaper publishing company. BMD was measured with a dual-energy X-ray densitometer at the lumbar spine (L2-4), femoral neck, distal femur, patella, proximal tibia, calcaneus and distal radius. In addition, maximal isometric strength, cardiorespiratory fitness, anthropometry, 4-day dietary record and daily occupational work load were assessed. During one work shift the carriers' mean walking distance was 5926 m, with 68 flights of stairs walked, and their mean heart rate was 105 beats/min (114 beats/min during the delivery). The corresponding figures for the office workers were significantly lower: 1895 m, 10 flights and 82 beats/min, respectively. Neither the BMD values adjusted for body mass index (kg/m2) and calcium intake nor the indices of physical performance capacity showed significant differences between the groups. Consequently, habitual daily walking and stair climbing by healthy premenopausal women appeared to be insufficient exercise stimulus to increase considerably the BMD or aerobic and muscular fitness above the values found in a comparable group of sedentary office workers.

Total energy expenditure and energy intake in the pre-school child: a comparison

In a cohort (n 81) of healthy children aged 1.5-4.5 years, measurements of energy intake and energy expenditure were compared. Energy intake was calculated following a 4 d weighed record completed by the mother or guardian of the child. Total energy expenditure was measured using the doubly-labelled water technique. Mean energy intake and expenditure in the cohort were 4773 kJ/d and 4928 kJ/d respectively. The mean relative bias between the techniques was 154 kJ/d. In the older children (3.5-4.5 years) the mean relative bias was only 37 kJ/d. At the population level the measurements of energy intake and energy expenditure were extremely close, and the study has provided sufficient confidence in weighed intake methodology for it to be used in a major nationwide study of dietary intake and nutritional status of children aged 1.5-4.5 years.

Evaluation of the dietary intake of homebound elderly and the feasibility of dietary supplementation

OBJECTIVE

The dietary intake of elderly subjects receiving home care services (n = 145) was studied to assess the adequacy of their intake, and their ability to maintain normal body weight. In a second part of the study, the feasibility of providing nutrient supplements to underweight subjects or those with important recent weight loss was evaluated.

METHOD

For the survey, three 24-hour recalls, height, weight and lifestyle habits were evaluated in a home interview and two follow-up telephone contacts. The effects of dietary supplementation of 14 subjects at risk of malnutrition (underweight or with substantial weight loss) over 12 weeks were evaluated.

RESULTS

Mean energy intake for the entire group was low (males 1546 kcal; females 1152 kcal) and on average barely covered estimated resting energy expenditure. Recent weight loss was negatively correlated with energy intake among underweight subjects (R = -0.64; p < 0.001). Dietary supplementation resulted in an average increase in daily intake of 390 kcal with an average weight gain of 1.27 kg over the 12-week period. Weight change was directly associated with measures of functional status; hand-grip strength (r = 0.75; p = 0.002) and general well-being score (r = 0.46; p = 0.095).

CONCLUSION

Homebound elderly were at high risk of inadequate protein and energy intake. Dietary supplementation in high risk individuals was well tolerated and led to modest weight gain and improvements in general well-being.

A semiquantitative dietary history questionnaire for Chinese Americans

An 84-item, semiquantitative dietary history questionnaire was developed for epidemiologic studies of diet and diseases in Chinese Americans. The questionnaire is a 30-minute, face-to-face administered instrument designed especially for assessing mixed dishes; it consists of a food list and requires information on frequency of consumption and portion estimation. A nutrient database was compiled from many sources, but mostly from US Department of Agriculture publications. The relative validity of this food frequency questionnaire was tested among 74 Chinese women between the ages of 30 and 60 years living in the San Francisco Bay area against a 1-day recall deemed a typical day's diet. Correlation coefficients of nutrients from both methods ranged from 0.2 for total fat to 0.7 for calcium and were all statistically significant at less than the 0.001 level. Agreement between these two methods was assessed by the percentage of misclassification of quartile distributions. Around 10% were grossly misclassified and 50% were correct estimates of intake in the same highest quartile, while 73% were correctly placed in the two highest quartiles. This food frequency questionnaire can reasonably estimate the usual dietary intakes among Chinese Americans for epidemiologic studies, but further validation would be needed.

Effects of micronutrients and antioxidants on lipid peroxidation in human plasma and in cell culture

Plasma levels of triglycerides, retinol, cholesterol, lipid-phase antioxidants (alpha-, gamma-tocopherols, beta-carotene, alpha-carotene, lycopene, beta-cryptoxanthin and lutein/zeaxanthin), and thiobarbituric acid-reactive substances (TBA-RS), as an indicator of lipid peroxidation, were repeatedly determined in nine individuals over a 3-month period. Levels of TBA-RS were positively correlated with plasma triglycerides and gamma-tocopherol, and negatively correlated with plasma carotenoids. These results were consistent with in vitro cell culture studies which showed increased TBA-RS for cells supplemented with linolenic acid and decreased levels when treated with beta-carotene. We conclude that TBA-RS measurements in plasma accurately reflect the level of peroxidizable substrate as modified by the presence of a variety of dietary antioxidants, particularly carotenoids. Although the inter- and intra-individual variabilities for TBA-RS are comparable with the micronutrients and antioxidants measured in this study, high interassay variability and the strong association with the more commonly measured plasma triglycerides suggest the TBA-RS assay to be of limited use in epidemiologic studies. However, this assay does appear to be useful in cell culture studies where experimental conditions can be better controlled. Low ratios of inter- to intra-individual variability in some of the plasma micronutrient and lipid-phase antioxidants measured suggest that multiple samples may be required to characterize individuals in studies evaluating the relation between these plasma constituents and disease incidence.