Maintaining appetite in older adults is important for preventing malnutrition. Previous studies have shown seasonal variations in dietary intake, suggesting that appetite itself may vary with the seasons. Nevertheless, few studies have directly examined seasonal changes in appetite in older adults, particularly those living alone, who are at higher risk of malnutrition. Thus, the purpose of the present study was to identify when appetite declines throughout the year in older adults living alone and with others. Of the 60 adults aged 65 and older who participated in the study, 57 completed the longitudinal study over four seasons. Appetite for each season was assessed using the Simple Nutritional Appetite Questionnaire (SNAQ) and the visual analogue scale for hunger, satiety, and expectation of food intake. Nutritional status was assessed using the Mini Nutritional Assessment and the Food Frequency Questionnaire. The living arrangements of the participants were determined based on whether they were living alone or with others. The stratified analysis revealed seasonal changes in SNAQ scores exclusively among individuals living alone (p = 0.029, effect size = 0.280), who exhibited diminished appetite during summer compared to winter (p = 0.026, 95% CI: 0.076–1.258). No seasonal variation in appetite or nutritional status was observed in those living with others (p > 0.05). These findings highlight the importance of an approach that considers living arrangement and seasonality to ensure that older people maintain adequate appetite status throughout the year.

Diet can affect health directly or by altering the gut microbiota; thus, there are strong interrelationships between the gut immune system, gut microbiota and diet. This study examined the effects of ingesting AIN-93M purified diet (PD) on gut immune function and gut microbiota in DO11·10 mice, in which T cell–dependent and T cell–independent (TI) IgA can be analysed separately. Ingestion of the PD for 2 weeks reduced both T cell–dependent and TI secretory IgA in the faeces compared with non-PD, whereas the diet did not affect T cell–dependent and TI serum IgA. Ingestion of the PD had no effect on systemic immune system splenocyte responses. Ingestion of the PD reduced intestinal tissue expression levels of B-cell activating factor and A proliferation–inducing ligand, cytokines involved in TI-IgA production and polymeric Ig receptor, which transports IgA into the intestinal lumen. Co-abundance group (CAG) analysis of the intestinal microbiota was conducted based on correlations between changes in the abundance of bacterial genera, and the correlations between CAG and IgA were determined. The Allobaculum-dominated CAG expanded following ingestion of the PD, accompanied by an inverse correlation with the decrease in faecal IgA, whereas the Lactobacillus-dominated CAG shrank relative to the Allobaculum-dominated CAG. These results suggest that TI-IgA suppresses the expansion of some intestinal bacteria and that ingestion of the PD induces dysbiosis via impaired IgA secretion into the intestinal lumen.

Obesity and depression are highly prevalent diseases that are strongly correlated. At the same time, there is a growing gap in care, and treatment options should be improved and extended. Positive effects of a Mediterranean diet on mental health have already been shown in various studies. In addition to the physiological effects of nutrients, the way food is eaten, such as mindful eating, seems to play a role. The present study investigates the effect of a Mediterranean diet and mindful eating on depression severity in people with clinically diagnosed major depressive disorder and obesity. Participants will be randomised to one of the four intervention groups (Mediterranean diet, mindful eating, their combination and a befriending control group). The factorial design allows investigating individual effects as well as potential synergistic effects of the interventions. The study consists of a 12-week intervention period, where five individual appointments will take place, followed by a 12-week follow-up. The primary outcome is depression severity. Secondary outcomes are remission of depression, assessor-rated depression severity, quality of life, self-efficacy, BMI, waist:hip ratio and body composition; adherence to the Mediterranean diet and mindful eating will also be assessed. Alongside mediator and moderator analysis, a microbiome analysis, a qualitative evaluation and an economic analysis will be conducted. The study investigates an important health issue in a vulnerable target group. It allows to draw valuable conclusions regarding the effectiveness of different interventions and therefore contributes to improving available care options for people suffering from depression and obesity.