Association of the habitual dietary intake with the fatty liver index and effect modification by metabotypes in the population-based KORA-Fit study.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is an emerging threat for public health with diet being a major risk factor in disease development and progression. However, the effects of habitual food consumption on fatty liver are still inconclusive as well as the proposed role of the individuals' metabolic profiles. Therefore, the aim of our study is to examine the associations between diet and NAFLD with an emphasis on the influence of specific metabotypes in the general population. METHODS: A total of 689 participants (304 men and 385 women) of the KORA-Fit (S4) survey, a follow-up study of the population-based KORA cohort study running in the Region of Augsburg, Germany, were included in this analysis. Dietary information was derived from repeated 24-h food lists and a food frequency questionnaire. The intake of energy and energy-providing nutrients were calculated using the national food composition database. The presence of fatty liver was quantified by the fatty liver index (FLI), and metabotypes were calculated using K-means clustering. Multivariable linear regression models were used for the analysis of habitual food groups and FLI; for the evaluation of macronutrients, energy substitution models were applied. RESULTS: A higher consumption of nuts and whole grains, and a better diet quality (according to Alternate Healthy Eating Index and Mediterranean Diet Score) were associated with lower FLI values, while the intake of soft drinks, meat, fish and eggs were associated with a higher FLI. The isocaloric substitution of carbohydrates with polyunsaturated fatty acids was associated with a decreased FLI, while substitution with monounsaturated fatty acids and protein showed increased FLI. Statistically significant interactions with the metabotype were observed for most food groups. CONCLUSION: The consumption of plant-based food groups, including nuts and whole grains, and diet quality, were associated with lower FLI values, whereas the intake of soft drinks and products of animal origin (meat, fish, eggs) were associated with a higher FLI. The observed statistically significant interactions with the metabotype for most food groups could help to develop targeted prevention strategies on a population-based level if confirmed in independent prospective studies.

Are sleep duration, midpoint of sleep and sleep quality associated with dietary intake among Bavarian adults?

BACKGROUND/OBJECTIVES: Only few epidemiologic studies examined sleep characteristics in relation to dietary behaviour. Our aim was to analyse associations of sleep duration, midpoint of sleep and sleep quality with dietary intake among the Bavarian population. SUBJECTS/METHODS: Within the cross-sectional Bavarian Food Consumption Survey II, 1050 subjects aged 13-81 years were recruited. Dietary intake was assessed with three 24-h dietary recalls by telephone (EPIC-Soft). In our study, 814 participants aged 18 years or older, who completed at least two 24-h dietary recalls and who had complete and plausible information on sleep characteristics were analysed. Dietary intake was described by the consumption of main food groups, energy-proving nutrients and energy intake. Sleep was measured by the Pittsburgh Sleep Quality Index Questionnaire, from which categories of self-reported usual sleep duration in half-h-steps per night, midpoint of sleep and overall sleep quality were derived. RESULTS: Sleep duration was associated with intake of non-alcoholic beverages (P<0.01), carbonated beverages (P=0.04), water (P=0.04) and coffee/black tea (P=0.01) with higher intake among short duration sleepers. No association was found between the consumption of other main food groups, energy-proving nutrients or total daily energy intake and sleep duration. Midpoint of sleep was associated with intake of carbonated beverages (P=0.02, highest intake among subjects with early midpoint of sleep). No association between sleep quality and dietary intake was detected. CONCLUSIONS: Our findings demonstrate only specific associations between sleep characteristics and dietary intake, and mainly sleep duration was associated with beverage intake.

Validation of anthropometry and foot-to-foot bioelectrical resistance against a three-component model to assess total body fat in children: the IDEFICS study.

OBJECTIVE: To compare different field methods for estimating body fat mass with a reference value derived by a three-component (3C) model in pre-school and school children across Europe. DESIGN: Multicentre validation study. SUBJECTS: Seventy-eight preschool/school children aged 4-10 years from four different European countries. METHODS: A standard measurement protocol was carried out in all children by trained field workers. A 3C model was used as the reference method. The field methods included height and weight measurement, circumferences measured at four sites, skinfold measured at two-six sites and foot-to-foot bioelectrical resistance (BIA) via TANITA scales. RESULTS: With the exception of height and neck circumference, all single measurements were able to explain at least 74% of the fat-mass variance in the sample. In combination, circumference models were superior to skinfold models and height-weight models. The best predictions were given by trunk models (combining skinfold and circumference measurements) that explained 91% of the observed fat-mass variance. The optimal data-driven model for our sample includes hip circumference, triceps skinfold and total body mass minus resistance index, and explains 94% of the fat-mass variance with 2.44 kg fat mass limits of agreement. In all investigated models, prediction errors were associated with fat mass, although to a lesser degree in the investigated skinfold models, arm models and the data-driven models. CONCLUSION: When studying total body fat in childhood populations, anthropometric measurements will give biased estimations as compared to gold standard measurements. Nevertheless, our study shows that when combining circumference and skinfold measurements, estimations of fat mass can be obtained with a limit of agreement of 1.91 kg in normal weight children and of 2.94 kg in overweight or obese children.

The IDEFICS validation study on field methods for assessing physical activity and body composition in children: design and data collection.

OBJECTIVE: To describe the design, measurements and fieldwork of the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) physical activity and body composition validation study, and to determine the potential and limitations of the data obtained. DESIGN: Multicentre validation study. SUBJECTS: A total of 98 children from four different European countries (age: 4-10 years). METHODS: An 8-day measurement protocol was carried out in all children using a collaborative protocol. Reference methods were the doubly labelled water method for physical activity, and a three- and a four-compartment model for body composition. Investigated field methods were accelerometers, a physical activity questionnaire and various anthropometric measurements. RESULTS: For the validation of physical activity field methods, it was possible to gather data from 83 to 89 children, laying the basis for age- and sex-specific results. The validation of body composition field methods is possible in 64-80 children and allows sex-specific analyses but has only limited statistical power in the youngest age group (<6 years). The amount of activity energy expenditure (AEE) varied between centres, sexes and age groups, with boys and older children having higher estimates of AEE. After normalisation of AEE by body weight, most group-specific differences diminished, except for country-specific differences. CONCLUSION: The IDEFICS validation study will allow age- and sex-specific investigation of questions pertaining to the validity of several field methods of body composition and physical activity, using established reference methods in four different European countries. From the participant analyses it can be concluded that the compliance for the investigated field methods was higher than that for the reference methods used in this validation study.

Prevalence and determinants of childhood overweight and obesity in European countries: pooled analysis of the existing surveys within the IDEFICS Consortium.

OBJECTIVE: To pool and analyse, according to standardized criteria and using harmonized variables, the existing databases of surveys on childhood overweight and obesity carried out from 1995 to 2005 in different European countries by research groups participating in the IDEFICS project. METHODS: Detailed information from seven surveys in five European countries was collected. A common database was built after harmonization of the single studies regarding sample size and age distribution. Variables were critically reviewed and harmonized according to a common protocol. On the pooled database, descriptive comparative analyses on the prevalence of overweight/obesity and association analyses of these conditions with perinatal, parental and environmental factors were performed. RESULTS: Starting from total number of 74,871 children, data of 18,626 children were included in the common database (Belgium, n=1766; Cyprus, n=5540; Estonia, n=583; Italy, n=4480 and Sweden, n=6257). After the exclusion of children outside the defined age ranges (4-5 and 9-11 years), the analysis was conducted on 1738 younger and 12,923 older children. Relevant differences in the prevalence of overweight/obesity were observed between countries in both age groups, the highest values being observed in Italy. Age- and gender-related associations between the risk of obesity/overweight and perinatal, parental and environmental factors were observed. An increased risk of high blood pressure in overweight/obese children was consistently observed. CONCLUSIONS: The results of this collaborative work of European research centres, although providing potentially useful findings, confirmed that the validity of comparisons between communities depends critically on the comparability of the survey methods. To monitor the current epidemic of childhood obesity and develop appropriate prevention strategies, a coordinated European approach is needed to collect homogeneous sets of epidemiological data.

[Integration of genetic factors into epidemiological studies]. / Die Einbeziehung genetischer Faktoren in Studien der Epidemiologie.

During the last two decades, genetic epidemiology has been established in parallel to the area of classical epidemiology. This paper presents some essentials of the epidemiology of genetic factors. It begins with a discussion of complex diseases that are characterized by an involvement of several genes. The problems that are attached to modeling gene-gene and gene-environment interactions and their integration into causal pathways are elucidated and the role of genetic factors in the etiology of complex diseases is investigated. Classical and new epidemiological study designs that allow an integration of genetic data are introduced. The introduction of this data is partly motivated by the danger of bias due to genetic heterogeneity (population stratification) in classical designs. The problem of replication of study results is discussed and the concept of Mendelian randomization is presented.