Extensive research demonstrates unequivocally that nutrition plays a fundamental role in maintaining health and preventing disease. In parallel nutrition research provides evidence that the risks and benefits of diet and lifestyle choices do not affect people equally, as people are inherently variable in their responses to nutrition and associated interventions to maintain health and prevent disease. To simplify the inherent complexity of human subjects and their nutrition, with the aim of managing expectations for dietary guidance required to ensure healthy populations and individuals, nutrition researchers often seek to group individuals based on commonly used criteria. This strategy relies on demonstrating meaningful conclusions based on comparison of group mean responses of assigned groups. Such studies are often confounded by the heterogeneous nutrition response. Commonly used criteria applied in grouping study populations and individuals to identify mechanisms and determinants of responses to nutrition often contribute to the problem of interpreting the results of group comparisons. Challenges of interpreting the group mean using diverse populations will be discussed with respect to studies in human subjects, in vivo and in vitro model systems. Future advances in nutrition research to tackle inter-individual variation require a coordinated approach from funders, learned societies, nutrition scientists, publishers and reviewers of the scientific literature. This will be essential to develop and implement improved study design, data recording, analysis and reporting to facilitate more insightful interpretation of the group mean with respect to population diversity and the heterogeneous nutrition response.

Diets high in glycaemic index (GI) and glycaemic load (GL) have been associated with a higher diabetes risk. Beer explained a large proportion of variation in GI in a Finnish and an American study. However, few beers have been tested according to International Organization for Standardization (ISO) methodology. We tested the GI of beer and estimated its contribution to dietary GI and GL in the Netherlands. GI testing of pilsner beer (Pilsner Urquell) was conducted at The University of Sydney according to ISO international standards with glucose as the reference food. Subsequently, GI and GL values were assigned to 2556 food items in the 2011 Dutch food composition table using a six-step methodology and consulting four databases. This table was linked to dietary data from 2106 adults in the Dutch National Food Consumption Survey 2007–2010. Stepwise linear regression identified contribution to inter-individual variation in dietary GI and GL. The GI of pilsner beer was 89 (sd 5). Beer consumption contributed to 9·6 and 5·3 % inter-individual variation in GI and GL, respectively. Other foods that contributed to the inter-individual variation in GI and GL included potatoes, bread, soft drinks, sugar, candy, wine, coffee and tea. The results were more pronounced in men than in women. In conclusion, beer is a high-GI food. Despite its relatively low carbohydrate content (approximately 4–5 g/100 ml), it still made a contribution to dietary GL, especially in men. Next to potatoes, bread, sugar and sugar-sweetened beverages, beer captured a considerable proportion of between-person variability in GI and GL in the Dutch diet.

The project Dialect Levelling in West Sweden focuses on the dialect situation in the first decade of the 21st century compared with the dialects spoken in the same region in the 1940s–1960s. Seventy teenagers participating in group interviews have been recorded and their use of phonological and morphological variables has been analysed. Comparisons with data recorded in the same region by The Institute of Language and Folklore in 1940–1960 show that dialect levelling is under way. It seems that the population of this area no longer speak a traditional dialect. An important issue, however, is how much the traditional dialects have actually changed, and to what extent the method for collecting data affects the answer. In the mid-20th century, the praxis within Swedish dialectology for selecting informants was to find as old and rural dialect speakers as possible to represent a specific region, and the purpose was that of documenting the dialect as a linguistic system. Today, however, many studies select informants based on speaker variables, because the aim is to document the dialect situation (i.e. who uses what linguistic variants when), rather than the traditional dialect as a linguistic system. Thus, there is a distinct difference between a linguistic interest and a sociolinguistic one. In this paper I suggest that it is critical when discussing dialect change to observe this very methodological change. In order to illustrate this, the use of dialect variants by two informants recorded in 1948 is compared with the use of dialect variants by three informants recorded in 2007 and 2008. The informants are all from around a small rural village located approximately 70 km from Gothenburg in West Sweden. This is an area where a specific variety of West Swedish has been spoken. By comparing these individuals, the concept of dialect change is problematized.