Cross-sectional Human Observational Study of Energy and Nutrient Uptake and the Intestinal Microbiome (ErNst)
Background: Nutritional monitoring, e.g., on the national level, requires the assessment of reliable representative dietary intake data. To achieve this, standardised tools need to be developed, validated and kept up-to-date with recent developments of food products and nutritional behaviour of the population. Recently, the human intestinal microbiome has been identified as an essential mediator between nutrition and host health. Despite growing interest in this connection, only few associations between microbiome, nutrition and health have been clearly established. Available studies paint an inconsistent picture, partly due to a lack of standardisation.  Objective: The ErNst Study (‚Erfassung der Energie- und Nährstoffzufuhr', engl. ‚assessment of energy and nutrient intake') addresses two objectives. Firstly, to verify if food consumption as well as energy and nutrient intake of the German population can be recorded validly by means of the dietary recall software GloboDiet, which will be applied in the German National Nutrition Monitoring. And secondly, to obtain high quality data using standardised methods on the microbiome, combined with dietary intake data and additional faecal sample material to also assess the functional activity of the microbiome by measuring microbial metabolites. Methods: Healthy female and male participants aged between 18 and 79 years were recruited. Anthropometric measurements included body height and weight, body mass index and bioelectric impedance analysis (BIA). For the purpose of validation of the GloboDiet software, current food consumption was assessed with a 24-h recall. Nitrogen and potassium concentrations were measured from 24-h urine collections to enable comparison with the intake of protein and potassium estimated by the GloboDiet software. Physical activity was measured over a period of at least 24 h using a wearable accelerometer to validate the estimated energy intake. Stool samples were collected in duplicate for a single timepoint and used for DNA isolation and subsequent amplification and sequencing of the 16S rRNA gene to determine microbiome composition. For the identification of associations between nutrition and microbiome, the habitual diet was determined using a food frequency questionnaire (FFQ) covering a period of 30 days.  Results: In total, 117 participants met the inclusion criteria. The study population was equally distributed between the sexes and three age groups (18 – 39, 40 – 59, 60 – 79 years). Stool samples accompanying habitual diet data (30-d FFQ) are available for 106 participants. Current diet data and 24-h urine samples for the validation of GloboDiet are available for 109 participants, of which 82 cases also include physical activity data. Conclusions: We completed recruitment and sample collection of the ErNst study with a high degree of standardisation. Samples and data will be used to validate the GloboDiet software for the German National Nutrition Monitoring and to compare microbiome composition and nutritional patterns.