Associations Between Diet, Metabolic Profile, and Cognitive Function in Men with Schizophrenia and Healthy Controls: Evidence from a Comparative Study

Introduction: Growing evidence indicates that diet quality significantly influences metabolic parameters and cognitive functioning. In healthy individuals, higher consumption of minimally processed foods and products rich in omega-3 fatty acids is associated with a more favorable lipid profile and better cognitive performance. Patients with schizophrenia present an increased risk of metabolic disturbances and reduced cognitive functioning. This suggests that this group may be particularly sensitive to nutritional factors. However, relatively few studies have simultaneously examined the relationships between diet, metabolism, and cognitive profile in patients with schizophrenia and healthy individuals. Aim: The aim of the study was to compare the relationships between the frequency of consumption of selected food categories and metabolic parameters (glycemia, lipid profile, and insulin resistance), as well as cognitive functions (Stroop Test, Trail Making Test, and verbal fluency), in patients with schizophrenia and healthy men. Methods: The study included 21 patients with schizophrenia and 20 healthy men. All participants completed a questionnaire assessing the frequency of food consumption. Blood samples were collected to determine glucose, insulin, HDL, LDL, and triglyceride levels, and the HOMA-IR index was calculated. Cognitive functioning was assessed using the Stroop Test (RCNb, NCWd) and the Trail Making Test (TMT-A and TMT-B), which measure psychomotor speed and visuospatial working memory, respectively, and the verbal fluency test (semantic and phonological). Correlation analyses were performed separately in both groups. Due to the small sample size, all correlations are treated as exploratory and are analyzed with correction for multiple comparisons. Results: Exploratory analyses identified several patterns of associations between the frequency of consumption of selected food categories, metabolic parameters, and cognitive performance in both healthy men and patients with schizophrenia. The observed patterns differed between groups, suggesting that clinical status and treatment-related factors may modify diet–metabolism–cognition relationships. These findings highlight potential pathways linking dietary habits with metabolic and cognitive outcomes and provide a basis for further hypothesis-driven research. Conclusions: Diet quality may be related to metabolic status and cognitive functioning. However, the pattern of these associations differs between patients with schizophrenia and healthy individuals. The findings suggest that diet may play a role in metabolic health and cognitive functioning, particularly in clinical populations.