Dietary preferences in the context of intra-couple dynamics: Relationship types within the German NutriAct family cohort.

To promote healthy diets in older age, a comprehensive understanding of factors influencing dietary behaviour and underlying preferences is essential. Romantic relationships are focal socialisation contexts, in which diet-related preferences and practices are dynamically negotiated. Our aim was to reconstruct intra-couple dynamics shaping dietary preferences and comparatively analyse relationship types among older couples. Data basis was the NutriAct Family Study - a German web-based cohort. Analyses were based on three a priori defined relationship types: 1) both partners' mutual adaptation of dietary preferences (symmetrical convergence), 2) unilateral adaptation (asymmetrical convergence) and 3) persistence of individual preferences. Relationship types were, among others, comparatively analysed using ANOVAs. Intra-couple dynamics within the asymmetrical convergence type were measured by multivariate logistic regression. The dyadic sample consisted of 398 couples resp. N = 796 individuals aged 63.99 years (SD = 6.15). All three relationship types were identified (symmetrical convergence: n = 62, 15.6 %; asymmetrical convergence: n = 199, 50.0 %; persistence: n = 137, 34.4 %). Within the asymmetrical convergence type, women were more likely to take a dominating role compared to their male partners (OR: 24.40; 95%CI: 14.37-41.41). This study demonstrates the fundamental influence of intra-couple dynamics on individual dietary preferences, whereby traditional gender roles have shown to play a central moderating role. Our study findings are relevant for the development and implementation of public health (nutrition) strategies, since they highlight the importance of understanding dietary preferences as jointly constructed and shaped in the intra-couple context, rather than as isolated, individually developed ones. In this context, future research directions and practical implications targeting not only individuals but involving couples are discussed.