Evaluation of under- and overreporting of energy intake in the 24-hour diet recalls in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVE

To evaluate under- and overreporting and their determinants in the EPIC 24-hour diet recall (24-HDR) measurements collected in the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN

Cross-sectional analysis. 24-HDR measurements were obtained by means of a standardised computerised interview program (EPIC-SOFT). The ratio of reported energy intake (EI) to estimated basal metabolic rate (BMR) was used to ascertain the magnitude, impact and determinants of misreporting. Goldberg's cut-off points were used to identify participants with physiologically extreme low or high energy intake. At the aggregate level the value of 1.55 for physical activity level (PAL) was chosen as reference. At the individual level we used multivariate statistical techniques to identify factors that could explain EI/BMR variability. Analyses were performed by adjusting for weight, height, age at recall, special diet, smoking status, day of recall (weekday vs. weekend day) and physical activity.

SETTING

Twenty-seven redefined centres in the 10 countries participating in the EPIC project.

SUBJECTS

In total, 35 955 men and women, aged 35-74 years, participating in the nested EPIC calibration sub-studies.

RESULTS

While overreporting has only a minor impact, the percentage of subjects identified as extreme underreporters was 13.8% and 10.3% in women and men, respectively. Mean EI/BMR values in men and women were 1.44 and 1.36 including all subjects, and 1.50 and 1.44 after exclusion of misreporters. After exclusion of misreporters, adjusted EI/BMR means were consistently less than 10% different from the expected value of 1.55 for PAL (except for women in Greece and in the UK), with overall differences equal to 4.0% and 7.4% for men and women, respectively. We modelled the probability of being an underreporter in association with several individual characteristics. After adjustment for age, height, special diet, smoking status, day of recall and physical activity at work, logistic regression analyses resulted in an odds ratio (OR) of being an underreporter for the highest vs. the lowest quartile of body mass index (BMI) of 3.52 (95% confidence interval (CI) 2.91-4.26) in men and 4.80 (95% CI 4.11-5.61) in women, indicating that overweight subjects are significantly more likely to underestimate energy intake than subjects in the bottom BMI category. Older people were less likely to underestimate energy intake: ORs were 0.58 (95% CI 0.45-0.77) and 0.74 (95% CI 0.63-0.88) for age (> or =65 years vs. <50 years). Special diet and day of the week showed strong effects.

CONCLUSION

EI tends to be underestimated in the vast majority of the EPIC centres, although to varying degrees; at the aggregate level most centres were below the expected reference value of 1.55. Underreporting seems to be more prevalent among women than men in the EPIC calibration sample. The hypothesis that BMI (or weight) and age are causally related to underreporting seems to be confirmed in the present work. This introduces further complexity in the within-group (centre or country) and between-group calibration of dietary questionnaire measurements to deattenuate the diet-disease relationship.

Variability of fish consumption within the 10 European countries participating in the European Investigation into Cancer and Nutrition (EPIC) study

OBJECTIVE

To describe and compare the consumption of total fish (marine foods) and the fish sub-groups - white fish, fatty fish, very fatty fish, fish products and crustacea, in participants from the European Investigation into Cancer and Nutrition (EPIC) study.

DESIGN

Cross-sectional analysis of dietary intake using a computerised standardised 24-hour recall interview. Crude means, means and standard errors adjusted by age, season and day of the week were calculated, stratified by centre and gender.

SETTING

Twenty-seven redefined centres in the 10 European countries participating in the EPIC study.

SUBJECTS

In total, 35 955 subjects (13 031 men and 22 924 women), aged 35-74 years, selected from the main EPIC cohort.

RESULTS

A six- to sevenfold variation in total fish consumption exists in women and men, between the lowest consumption in Germany and the highest in Spain. Overall, white fish represented 49% and 45% of the intake of total fish in women and men, respectively, with the greatest consumption in centres in Spain and Greece and the least in the German and Dutch centres. Consumption of fatty fish reflected that of total fish. However, the greatest intake of very fatty fish was in the coastal areas of northern Europe (Denmark, Sweden and Norway) and in Germany. Consumption of fish products was greater in northern than in southern Europe, with white fish products predominating in centres in France, Italy, Spain, The Netherlands and Norway. Intake of roe and roe products was low. The highest consumption of crustacea was found in the French, Spanish and Italian centres. The number of fish types consumed was greater in southern than in northern Europe. The greatest variability in consumption by day of the week was found in the countries with the lowest fish intake.

CONCLUSIONS

Throughout Europe, substantial geographic variation exists in total fish intake, fish sub-groups and the number of types consumed. Day-to-day variability in consumption is also high.

Diversity of dietary patterns observed in the European Prospective Investigation into Cancer and Nutrition (EPIC) project

OBJECTIVE

To describe the diversity in dietary patterns existing across centres/regions participating in the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN AND SETTING

Single 24-hour dietary recall measurements were obtained by means of standardised face-to-face interviews using the EPIC-SOFT software. These have been used to present a graphic multi-dimensional comparison of the adjusted mean consumption of 22 food groups.

SUBJECTS

In total, 35 955 men and women, aged 35-74 years, participating in the EPIC nested calibration study.

RESULTS

Although wide differences were observed across centres, the countries participating in EPIC are characterised by specific dietary patterns. Overall, Italy and Greece have a dietary pattern characterised by plant foods (except potatoes) and a lower consumption of animal and processed foods, compared with the other EPIC countries. France and particularly Spain have more heterogeneous dietary patterns, with a relatively high consumption of both plant foods and animal products. Apart from characteristics specific to vegetarian groups, the UK 'health-conscious' group shares with the UK general population a relatively high consumption of tea, sauces, cakes, soft drinks (women), margarine and butter. In contrast, the diet in the Nordic countries, The Netherlands, Germany and the UK general population is relatively high in potatoes and animal, processed and sweetened/refined foods, with proportions varying across countries/centres. In these countries, consumption of vegetables and fruit is similar to, or below, the overall EPIC means, and is low for legumes and vegetable oils. Overall, dietary patterns were similar for men and women, although there were large gender differences for certain food groups.

CONCLUSIONS

There are considerable differences in food group consumption and dietary patterns among the EPIC study populations. This large heterogeneity should be an advantage when investigating the relationship between diet and cancer and formulating new aetiological hypotheses related to dietary patterns and disease.

Consumption of dairy products in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort: data from 35 955 24-hour dietary recalls in 10 European countries

OBJECTIVES

To describe and compare the consumption of dairy products in cohorts included in the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

Data from single 24-hour dietary recall interviews collected through a highly standardised computer-based program (EPIC-SOFT) in 27 redefined centres in 10 European countries between 1995 and 2000. From a total random sample of 36 900, 22 924 women and 13 031 men were selected after exclusion of subjects under 35 and over 74 years of age.

RESULTS

A high total consumption of dairy products was reported in most of the centres in Spain and in the UK cohort sampled from the general population, as well as in the Dutch, Swedish and Danish centres. A somewhat low consumption was reported in the Greek centre and in some of the Italian centres (Ragusa and Turin). In all centres and for both sexes, milk constituted the dairy sub-group with the largest proportion (in grams) of total dairy consumption, followed by yoghurt and other fermented milk products, and cheese. Still, there was a wide range in the contributions of the different dairy sub-groups between centres. The Spanish and Nordic centres generally reported a high consumption of milk, the Swedish and Dutch centres reported a high consumption of yoghurt and other fermented milk products, whereas the highest consumption of cheese was reported in the French centres.

CONCLUSION

The results demonstrate both quantitative and qualitative disparities in dairy product consumption among the EPIC centres. This offers a sound starting point for analyses of associations between dairy intake and chronic diseases such as cancer.

Meat consumption in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohorts: results from 24-hour dietary recalls

OBJECTIVE

To evaluate meat intake patterns in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohorts.

DESIGN AND SETTING

24-Hour dietary recalls were assessed within the framework of a prospective cohort study in 27 centres across 10 European countries by means of standardised computer-assisted interviews.

SUBJECTS

In total, 22 924 women and 13 031 men aged 35-74 years.

RESULTS

Mean total meat intake was lowest in the 'health-conscious' cohort in the UK (15 and 21 g day-1 in women and men, respectively) and highest in the north of Spain, especially in San Sebastian (124 and 234 g day-1, respectively). In the southern Spanish centres and in Naples (Italy), meat consumption was distinctly lower than in the north of these countries. Central and northern European centres/countries showed rather similar meat consumption patterns, except for the British and French cohorts. Differences in the intake of meat sub-groups (e.g. red meat, processed meat) across EPIC were even higher than found for total meat intake. With a few exceptions, the Mediterranean EPIC centres revealed a higher proportion of beef/veal and poultry and less pork or processed meat than observed in central or northern European centres. The highest sausage consumption was observed for the German EPIC participants, followed by the Norwegians, Swedish, Danish and Dutch.

CONCLUSIONS

The results demonstrate distinct differences in meat consumption patterns between EPIC centres across Europe. This is an important prerequisite for obtaining further insight into the relationship between meat intake and the development of chronic diseases.

Consumption of added fats and oils in the European Prospective Investigation into Cancer and Nutrition (EPIC) centres across 10 European countries as assessed by 24-hour dietary recalls

OBJECTIVE

To evaluate the consumption of added fats and oils across the European centres and countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN AND SETTING

24-Hour dietary recalls were collected by means of standardised computer-guided interviews in 27 redefined EPIC centres across 10 European countries.

SUBJECTS

From an initial number of 36 900 subjects, single dietary recalls from 22 924 women and 13 031 men in the age range of 35-74 years were included.

RESULTS

Mean daily intake of added fats and oils varied between 16.2 g (Varese, Italy) and 41.1 g (Malmö, Sweden) in women and between 24.7 g (Ragusa, Italy) and 66.0 g (Potsdam, Germany) in men. Total mean lipid intake by consumption of added fats and oils, including those used for sauce preparation, ranged between 18.3 (Norway) and 37.2 g day-1 (Greece) in women and 28.4 (Heidelberg, Germany) and 51.2 g day-1 (Greece) in men. The Mediterranean EPIC centres with high olive oil consumption combined with low animal fat intake contrasted with the central and northern European centres where fewer vegetable oils, more animal fats and a high proportion of margarine were consumed. The consumption of added fats and oils of animal origin was highest in the German EPIC centres, followed by the French. The contribution of added fats and oils to total energy intake ranged from 8% in Norway to 22% in Greece.

CONCLUSIONS

The results demonstrate a high variation in dietary intake of added fats and oils in EPIC, providing a good opportunity to elucidate the role of dietary fats in cancer aetiology.

Patterns of alcohol consumption in 10 European countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC) project

OBJECTIVE

The aim of this study was to compare the quantities of alcohol and types of alcoholic beverages consumed, and the timing of consumption, in centres participating in the European Prospective Investigation into Cancer and Nutrition (EPIC). These centres, in 10 European countries, are characterised by widely differing drinking habits and frequencies of alcohol-related diseases.

METHODS

We collected a single standardised 24-hour dietary recall per subject from a random sample of the EPIC cohort (36 900 persons initially and 35 955 after exclusion of subjects under 35 and over 74 years of age). This provided detailed information on the distribution of alcohol consumption during the day in relation to main meals, and was used to determine weekly consumption patterns. The crude and adjusted (by age, day of week and season) means of total ethanol consumption and consumption according to type of beverage were stratified by centre and sex.

RESULTS

Sex was a strong determinant of drinking patterns in all 10 countries. The highest total alcohol consumption was observed in the Spanish centres (San Sebastian, 41.4 g day-1) for men and in Danish centres (Copenhagen, 20.9 g day-1) for women. The lowest total alcohol intake was in the Swedish centres (Umeå, 10.2 g day-1) in men and in Greek women (3.4 g day-1). Among men, the main contributor to total alcohol intake was wine in Mediterranean countries and beer in the Dutch, German, Swedish and Danish centres. In most centres, the main source of alcohol for women was wine except for Murcia (Spain), where it was beer. Alcohol consumption, particularly by women, increased markedly during the weekend in nearly all centres. The German, Dutch, UK (general population) and Danish centres were characterised by the highest percentages of alcohol consumption outside mealtimes.

CONCLUSIONS

The large variation in drinking patterns among the EPIC centres provides an opportunity to better understand the relationship between alcohol and alcohol-related diseases.

Consumption of vegetables, fruit and other plant foods in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohorts from 10 European countries

OBJECTIVE

To describe and compare the consumption of the main groups and sub-groups of vegetables and fruits (V&F) in men and women from the centres participating in the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN

Cross-sectional analysis. Dietary intake was assessed by means of a 24-hour dietary recall using computerised interview software and standardised procedures. Crude and adjusted means were computed for the main groups and sub-groups of V&F by centre, separately for men and women. Adjusted means by season, day of the week and age were estimated using weights and covariance analysis.

SETTING

Twenty-seven centres in 10 European countries participating in the EPIC project.

SUBJECTS

In total, 35 955 subjects (13 031 men and 22 924 women), aged 35-74 years, randomly selected from each EPIC cohort.

RESULTS

The centres from southern countries had the highest consumption of V&F, while the lowest intake was seen in The Netherlands and Scandinavia for both genders. These differences were more evident for fruits, particularly citrus. However, slightly different patterns arose for some sub-groups of vegetables, such as root vegetables and cabbage. Adjustment for body mass index, physical activity, smoking habits and education did not substantially modify the mean intakes of vegetables and fruits.

CONCLUSIONS

Total vegetable and fruit intake follows a south-north gradient in both genders, whereas for several sub-groups of vegetables a different geographic distribution exists. Differences in mean intake of V&F by centre were not explained by lifestyle factors associated with V&F intake.

alpha-Linolenic acid intake is not beneficially associated with 10-y risk of coronary artery disease incidence: the Zutphen Elderly Study

BACKGROUND

Data on the relation between alpha-linolenic acid intake and coronary artery disease (CAD) are limited. Other dietary components appear to modify the reported relation between alpha-linolenic acid intake and CAD.

OBJECTIVE

We examined whether dietary alpha-linolenic acid intake was inversely associated with risk of CAD.

DESIGN

We prospectively studied 667 men aged 64-84 y from the Zutphen Elderly Study who were free of CAD at baseline. Dietary intake was assessed by using a cross-check dietary history method.

RESULTS

During the 10-y follow-up, we documented 98 cases of CAD. After adjustment for age, standard coronary risk factors, and intake of trans fatty acids and other nutrients, alpha-linolenic acid intake was not significantly associated with CAD risk. The relative risk of CAD for the highest compared with the lowest tertile of alpha-linolenic acid intake was 1.68 (95% CI: 0.86, 3.29). alpha-Linolenic acid intake from sources containing trans fatty acids was also nonsignificantly, yet positively, associated with CAD risk. alpha-Linolenic acid intake from foods that did not contain trans fatty acids was not associated with CAD risk, the relative risk of CAD for the highest compared with the lowest tertile was 1.15 (95% CI: 0.63, 2.11).

CONCLUSION

We did not observe a beneficial effect of dietary alpha-linolenic acid intake on the risk of 10-y CAD incidence. Investigating this hypothesis was complicated by the association between intakes of alpha-linolenic acid and trans fatty acids. Given the results of current prospective studies, a protective cardiac effect of alpha-linolenic acid is questionable.

Diet and chronic obstructive pulmonary disease: independent beneficial effects of fruits, whole grains, and alcohol (the MORGEN study)

BACKGROUND

In recent years antioxidants, foods rich in antioxidants (e.g. fruits, vegetables) and fish have been suggested to protect against chronic obstructive pulmonary disease (COPD). There are also indications for a protective effect of whole grain intake and of consuming moderate amounts of alcohol. It is, however, not clear whether the effects of the different dietary factors on COPD are independent of each other and if so, whether their effects are additive.

OBJECTIVE

To gain more insight into the potential protective effect of diet on COPD, we studied fruit, vegetable, fish, alcohol and whole grain consumption simultaneously in relation to pulmonary function and COPD symptoms.

METHODS

Analysed were cross-sectional data collected in 13 651 men and women aged 20-59 years participating between 1994 and 1997 in the MORGEN study (monitoring project on risk factors and health in The Netherlands). Regression models were adjusted for age, gender, height (for pulmonary function only), smoking, BMI and energy intake.

RESULTS

Fruit and whole grain intake showed independent beneficial associations with COPD (P-trend < 0.001). Furthermore, in subjects with low alcohol consumption (1-30 g/day) the forced expiratory volume in 1 s (FEV1) was higher and the prevalence of COPD symptoms lower than in non-drinkers (P < 0.001). The effects of a favourable intake of fruits (> 180 g/day), whole grains (> 45 g/day) and alcohol (1-30 g/day) were largely additive. In the 2998 subjects with a favourable intake of the three foods, the FEV1 was 139 mL higher and the prevalence of COPD symptoms lower (odds ratio (OR) = 0.44) than in subjects (n = 1406) with unfavourable intakes of fruits, whole grains and alcohol (P < 0.001). A similar effect was observed in those who had never smoked. Fish and vegetable intake did not show independent beneficial associations with COPD.

CONCLUSIONS

Our results suggest independent beneficial effects of fruits, whole grains and alcohol on COPD that are largely additive and cannot be explained by smoking habits.

Association between trans fatty acid intake and 10-year risk of coronary heart disease in the Zutphen Elderly Study: a prospective population-based study

BACKGROUND

Evidence on the relation between trans fatty acid intake and coronary heart disease is limited. We investigated this relation in a Dutch population with a fairly high trans fatty acid intake, including trans fatty acids from partly hydrogenated fish oils.

METHODS

We prospectively studied 667 men of the Zutphen Elderly Study aged 64-84 years and free of coronary heart disease at baseline. We used dietary surveys to establish the participants' food consumption patterns. Information on risk factors and diet was obtained in 1985, 1990, and 1995. After 10 years of follow-up from 1985-95, there were 98 cases of fatal or non-fatal coronary heart disease.

FINDINGS

Between 1985 and 1995, average trans fatty acid intake decreased from 4.3% to 1.9% of energy. After adjustment for age, body mass index, smoking, and dietary covariates, trans fatty acid intake at baseline was positively associated with the 10-year risk of coronary heart disease. The relative risk for a difference of 2% of energy in trans fatty acid intake at baseline was 1.28 (95% CI 1.01-1.61).

INTERPRETATION

A high intake of trans fatty acids (all types of isomers) contributes to the risk of coronary heart disease. The substantial decrease in trans fatty acid intake, mainly due to industrial lowering of trans contents in Dutch edible fats, could therefore have had a large public-health impact.

Standardization of the 24-hour diet recall calibration method used in the european prospective investigation into cancer and nutrition (EPIC): general concepts and preliminary results

OBJECTIVES

Despite increasing interest in the concept of calibration in dietary surveys, there is still little experience in the use and standardization of a common reference dietary method, especially in international studies. In this paper, we present the general theoretical framework and the approaches developed to standardize the computer-assisted 24 h diet recall method (EPIC-SOFT) used to collect about 37 000 24-h dietary recall measurements (24-HDR) from the 10 countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC). In addition, an analysis of variance was performed to examine the level of standardization of EPIC-SOFT across the 90 interviewers involved in the study.

METHODS

The analysis of variance used a random effects model in which mean energy intake per interviewer was used as the dependent variable, while age, body mass index (BMI), energy requirement, week day, season, special diet, special day, physical activity and the EPIC-SOFT version were used as independent variables. The analysis was performed separately for men and women.

RESULTS

The results show no statistical difference between interviewers in all countries for men and five out of eight countries for women, after adjustment for physical activity and the EPIC-SOFT program version used, and the exclusion of one interviewer in Germany (for men), and one in Denmark (for women). These results showed an interviewer effect in certain countries and a significant difference between gender, suggesting an underlying respondent's effect due to the higher under-reporting among women that was consistently observed in EPIC. However, the actual difference between interviewer and country mean energy intakes is about 10%. Furthermore, no statistical differences in mean energy intakes were observed across centres from the same country, except in Italy and Germany for men, and France and Spain for women, where the populations were recruited from areas scattered throughout the countries.

CONCLUSION

Despite these encouraging results and the efforts to standardize the 24-HDR interview method, conscious or unconscious behaviour of respondents and/or interviewer bias cannot be prevented entirely. Further evaluation of the reliability of EPIC-SOFT measurements will be conducted through validation against independent biological markers (nitrogen, potassium).

Structure of the standardized computerized 24-h diet recall interview used as reference method in the 22 centers participating in the EPIC project. European Prospective Investigation into Cancer and Nutrition

A computerized 24-h diet recall interview program (EPIC-SOFT) was developed for use in a large European multi-center study, namely the European Prospective Investigation into Cancer and Nutrition (EPIC). This program, which was adapted for each participating country and translated into nine languages, was developed to standardize interviews between the 22 EPIC centers. Common rules were pre-entered into the system to describe, quantify and probe approximately 1500-2200 foods and 150-350 recipes. Common methods used to classify and export the EPIC-SOFT dietary data facilitate their exchange, comparison and analysis. So far, EPIC-SOFT is the only available computerized 24-h diet recall system developed to provide comparable food consumption data between several European countries.

Determinants of obesity-related underreporting of energy intake

Data from an ongoing Dutch health examination monitoring project carried out in 1995 (n = 2,079 men and 2,467 women, aged 20-65 years) were used to study whether various determinants of underreporting of energy intake influenced the association between underreporting and body mass index. Further, the authors examined whether these determinants were mutually independent predictors of underreporting. As a measure for the degree of underreporting, they calculated energy ratios of reported daily energy intake divided by the estimated basal metabolic rate. They observed that underreporting occurred more with increasing degrees of overweight in men and women. Each increase in body mass index by 1 kg/m2 was associated with a decrease in reported energy intake/basal metabolic rate (in men, beta = -0.0364; standard error, 0.0024; in women, beta = -0.0262; standard error, 0.0018). After adjustment for age, education, smoking habits, physical activity, dieting behavior, and dieting frequency during the last year, the slopes were reduced by 29% in men and 17% in women but remained negative and highly statistically significant. Adjustment for current dieting behavior particularly decreased the association between body mass index and underreporting. Age was another independent determinant of underreporting in men and women and, in men only, so were smoking habits and education level. In conclusion, overweight individuals give biased dietary information, and this may distort the relations between self-reported dietary intake and diseases related to body mass index.

Underreporting of energy, protein and potassium intake in relation to body mass index

BACKGROUND

Differential underreporting of dietary intake by subgroups of body mass index (BMI) will confound associations between dietary intake and BMI-related diseases. We estimated the magnitude of BMI-related underreporting for energy, protein, and potassium intake for the Dutch cohorts of the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

The study population consisted of 134 Dutch men and women, aged 21-71 years, who participated in a pilot of EPIC. Ratios of reported dietary intakes to biomarkers were used as measures for underreporting. Dietary intake was assessed by a food frequency questionnaire (FFQ) and repeated 24-hour dietary recalls. Biomarker for energy intake was calculated basal metabolic rate; for protein and potassium intake the biomarker was 24-hour urinary nitrogen and potassium excretion, respectively. The measures of underreporting were linearly regressed on BMI (in kg/m2).

RESULTS

Significant negative regression coefficients were observed when regressing energy ratio on BMI with adjustment for physical activity (FFQ: beta = -0.04 for men, beta = -0.02 for women; 24-hour recalls: beta = -0.03 for men, beta = -0.04 for women). In men, a significant negative regression coefficient (beta = -0.03) was observed when regressing protein ratio on BMI; for the recalls however only after adjustment for age and education (beta = -0.02). In women, negative regression coefficients were also obtained, but for the FFQ only after exclusion of dieting women (both FFQ and 24-hour recalls: beta = -0.02). According to the recalls, but not the FFQ, a significant negative regression coefficient (beta = -0.02) was observed among women when regressing potassium ratio on BMI.

CONCLUSIONS

In this Dutch population, BMI-dependent underreporting of 20-25% over the observed range of BMI is present for protein and energy, Further study on BMI-dependent underreporting of dietary intake in EPIC cohorts is warranted.

Adherence to the European Code Against Cancer in relation to long-term cancer mortality: intercohort comparisons from the Seven Countries Study

Within the Seven Countries Study, we investigated whether population differences in 25-year cancer mortality and mortality due to cancer of the lung, stomach, and colorectum could be explained by population differences in adherence to the European Code Against Cancer. Baseline surveys were carried out around 1960 on 12,763 middle-aged men constituting 16 cohorts in seven countries; small samples of the cohorts kept dietary records. In 1987, food equivalent composites representing the average food intake of each cohort at baseline were collected locally and analyzed in one central laboratory. The vital status of all participants was verified after 25 years of follow-up. Overall adherence to the first four recommendations of the European Code Against Cancer was inversely related to 25-year total cancer mortality but not to all-cause mortality. The association with cancer mortality was essentially due to the inverse association for adherence to the guideline on smoking only. Each decrease in the percentage of smokers of 3.4% (10% of range) was associated with a relative risk of 0.93 of dying from cancer. Adherence to the recommendation on consumption of vegetables, fruits, and fiber-rich cereals was inversely related to stomach cancer mortality, whereas adherence to the recommendation on body weight, physical activity, and intake of fat was associated with higher stomach cancer mortality.

Dietary intake of antioxidant (pro)-vitamins, respiratory symptoms and pulmonary function: the MORGEN study

BACKGROUND

A study was undertaken to investigate the relationships between the intake of the antioxidant (pro)-vitamins C, E and beta-carotene and the presence of respiratory symptoms and lung function.

METHODS

Complete data were collected in a cross sectional study in a random sample of the Dutch population on 6555 adults during 1994 and 1995. Antioxidant intake was assessed by a semi-quantitative food frequency questionnaire and respiratory symptoms (cough, phlegm, productive cough, wheeze, shortness of breath) were assessed by a self-administered questionnaire. Prevalence odds ratios for symptoms were calculated using logistic regression analysis. Linear regression analysis was used for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). The results are presented as a comparison between the 90th and 10th percentiles of antioxidant intake.

RESULTS

Vitamin C intake was not associated with most symptoms but was inversely related with cough. Subjects with a high intake of vitamin C had a 53 ml (95% CI 23 to 83) higher FEV1 and 79 ml (95% CI 42 to 116) higher FVC than those with a low vitamin C intake. Vitamin E intake showed no association with most symptoms and lung function, but had a positive association with productive cough. The intake of beta-carotene was not associated with most symptoms but had a positive association with wheeze. However, subjects with a high intake of beta-carotene had a 60 ml (95% CI 31 to 89) higher FEV1 and 75 ml (95% CI 40 to 110) higher FVC than those with a low intake of beta-carotene.

CONCLUSIONS

The results of this study suggest that a high intake of vitamin C or beta-carotene is protective for FEV1 and FVC compared with a low intake, but not for respiratory symptoms.

Biochemical markers as additional measurements in dietary validity studies: application of the method of triads with examples from the European Prospective Investigation into Cancer and Nutrition

The validity coefficient of dietary questionnaire measurements can be estimated from a triangular comparison between questionnaire, reference, and biochemical marker measurements with the method of triads. The method assumes that the measurements are linearly related to true intake and have independent random errors. We applied the method of triads to examples from the European Prospective Investigation into Cancer and Nutrition. In some examples, Heywood cases occurred, ie, the estimated validity coefficients were > 1 or the validity coefficients were not estimable. Such results are caused by random sampling fluctuations or violation of the model assumptions. One possible violation is a positive correlation between the random errors of questionnaire and reference measurements. We used a bootstrap method to estimate CIs for the validity coefficients. Validity studies with several hundred subjects, more accurate biochemical indicators of dietary intake, or both, are needed to estimate validity coefficients precisely and avoid complications with the bootstrap method.

Plasma deoxycholic acid is related to deoxycholic acid in faecal water

Bile acids are considered as a risk factor for colorectal carcinogenesis. They were analysed in samples of faecal water and plasma of fasting heparine blood from 23 urolithiasis patients. Linear regression showed that the highest percentage of variance (52%) was explained by the model: plasma deoxycholic acid (micromol/l) = -3.11 + 0.96(+/-0.25*) 10log deoxycholic acid in faecal water (micromol/l) + 0.35(+/-0.15*) pH of faecal water -0.41(+/-0.19#) defacation frequency (number of stools/day); *P < 0.05, #P = 0.055. In future studies, analysing blood levels of unconjugated deoxycholic acid may substitute faecal measurements.

Repeated measurements of vegetables, fruits, beta-carotene, and vitamins C and E in relation to lung cancer. The Zutphen Study

The authors studied the intake of vegetables, fruits, beta-carotene, and vitamins C and E in relation to the incidence of lung cancer. For 561 men from the town of Zutphen, the Netherlands, dietary history information was obtained in 1960, 1965, and 1970. During 1971-1990, 54 new cases of lung cancer were identified. The data were analyzed using Cox proportional hazard analyses, adjusting for age, pack-years of cigarettes, and energy intake. No relation between intake of vitamin E and lung cancer risk was seen. For vitamin C intake, the results pointed to an inverse association, although not entirely consistently. Furthermore, it was observed that participants with low stable intakes (i.e., low in 1960, 1965, and 1970) of vegetables, fruits, and beta-carotene experienced more than twofold increased relative risks of lung cancer than those with high stable intakes. For participants with low average intakes, relative risks were much lower and not statistically significant. The authors conclude that there is no apparent relation of vitamin E to lung cancer risk; however, for beta-carotene, vitamin C, vegetables, and fruit, most studies, including the present one, suggest weak inverse associations. The use of repeated intake measurements to select subgroups with stable, highly contrasting intakes may be a promising approach for studying diet-cancer relations.

The Dutch EPIC food frequency questionnaire. I. Description of the questionnaire, and relative validity and reproducibility for food groups

BACKGROUND

A self-administered food frequency questionnaire was developed for the Dutch cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC). Habitual consumption of 178 food items can be calculated from the questionnaire data.

METHODS

Reproducibility and relative validity for food group intake were investigated in a population of 121 Dutch men and Women. The questionnaire was administered three times at 6-month intervals in order to determine the reproducibility. To assess the relative validity 12 monthly 24-hour recalls served as the reference method.

RESULTS

Spearman rank order correlation coefficients between estimates of food group intake assessed by repeated questionnaires ranged from 0.45 to 0.92. For men, Spearman correlation coefficients between estimates of food group intake based on the questionnaire and those based on 24-hour recalls ranged from 0.21 for cooked vegetables to 0.78 for sugar and sweet products, with a range of 0.61. For women the median was 0.53, with a minimum of 0.31 for vegetables and a maximum of 0.87 for alcoholic beverages. The photographs in the questionnaire for the estimation of portion sizes contributed little to the relative validity of the ranking of subjects. However, on the group level most median food group estimates based on photographic portion sizes were closer to the median intakes as assessed by 24-hour recalls than those based on standard portion sizes.

CONCLUSIONS

The questionnaire seems adequate for ranking Dutch EPIC subjects according to intake of most food groups, although the relative validity for some food groups, such as vegetables and fish, remains of concern.

Estimation of reproducibility and relative validity of the questions included in the EPIC Physical Activity Questionnaire

BACKGROUND

The EPIC core questionnaire on lifestyle contains a number of questions on physical activity designed to rank subjects according to level of physical activity (short PA questionnaire). These questions are based on a more extensive questionnaire designed to measure absolute total energy expenditure (extensive PA questionnaire), that was validated in a pilot study preceding EPIC. Reproducibility and relative validity of the short PA questionnaire were estimated by selecting, from the pilot study data, the answers to a number of questions from the extensive questionnaire that resembled those actually included in the short version.

METHODS

The population of the pilot study consisted of 126 men and women aged between 20 and 70 years. Reproducibility was estimated by administering the extensive questionnaire three times: at baseline, and after 5 and 11 months. In order to determine the relative validity of the extensive questionnaire, a 3-day activity diary, repeated four times, was used as the reference method.

RESULTS

Over the study period (13 months), mean absolute energy expenditure, estimated from the questions included in the short questionnaire, was fairly constant in men but not in women. REPRODUCIBILITY: Spearman correlation coefficients ranged from 0.47 to 0.89 in men, and from 0.49 to 0.81 in women. RELATIVE VALIDITY: Spearman correlation coefficients between the short questionnaire and the diary were between 0.32 and 0.81 for men, and between 0.28 and 0.72 for women.

CONCLUSIONS

The questions selected for the short questionnaire are not suitable for estimating energy expenditure at an absolute level. Reproducibility and relative validity of the ranking of subjects seemed satisfactory and comparable to the extensive questionnaire. The results imply that the short questionnaire is suitable for ranking subjects in the EPIC study.

The Dutch EPIC food frequency questionnaire. II. Relative validity and reproducibility for nutrients

BACKGROUND

A self-administered semi-quantitative food frequency questionnaire (FFQ) was developed for the Dutch cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

The reproducibility and relative validity of nutrient intake as assessed by this questionnaire were investigated in a population of 121 men and women. To assess the relative validity, 12 monthly 24-hour recalls served as reference method, together with four determinations of 24-hour urinary nitrogen excretion, predicted basal metabolic rate, and serum beta-carotene and alpha-tocopherol levels.

RESULTS

Protein and among women, energy intake were underestimated by the questionnaire compared to urinary nitrogen excretion and the basal metabolic rate, respectively. The underestimation for protein decreased with increasing protein intake. Pearson correlation coefficients between nutrient intakes assessed by repeated questionnaires ranged from 0.70 to 0.94 among men and from 0.59 to 0.94 among women. Correlation coefficients between nutrient intakes assessed by the questionnaire and 24-hour recalls ranged from 0.26 to 0.83 for men and from 0.35 to 0.90 for women, with medians of 0.59 and 0.58, respectively. Correlation coefficients between 0.2 and 0.5 were observed for beta-carotene and vitamin C for men and for beta-carotene and vitamin E for women. Associations with serum beta-carotene (r = -0.16 for men; 0.13 for women) and alpha-tocopherol (0.23 and 0.15, respectively) were much poorer than those obtained with 24-hour recalls. Correlations between protein intake and 24-hour urinary nitrogen excretion were 0.47 and 0.53, respectively.

CONCLUSIONS

The FFQ seems adequate for ranking subjects according to intake of energy, macronutrients, dietary fibre and retinol, but it does not yield such good results for beta-carotene, vitamin C for men, vitamin E for women.

Relative validity and repeatability of a new questionnaire on physical activity

BACKGROUND

A physical activity questionnaire was developed with the aim to estimate usual individual daily energy expenditure. The questionnaire focused on the number of hours usually spent on various activities. In a pilot study it was tested for repeatability and validity in a population of 126 Dutch adults (64 men, 62 women).

METHODS

For assessment of repeatability the questionnaire was administered three times during the course of 1 year. A four-times-repeated 3-day activity diary was used as a reference instrument to evaluate validity.

RESULTS

Differences in mean energy expenditure among repeated administrations of the questionnaire were small and not significant. Spearman's test-retest correlation coefficients for total energy expenditure for men were 0.76 [95% confidence interval (CI) 0.63-0.85] and 0.70 (95% CI 0.54-0.81) at 5 and 11 months, respectively, and for women were 0.58 (95% CI 0.36-0.74) and 0.71 (95% CI 0.54-0.82). There was a significant trend showing increasing mean diary energy expenditure for successive tertiles of questionnaire energy expenditure. The correlation between the questionnaire and the diary was 0.66 (95% CI 0.49-0.78) for men and 0.43 (95% CI 0.18-0.63) for women.

CONCLUSIONS

It was concluded that this questionnaire is a useful tool for estimating energy expenditure in epidemiological studies.