Abstract
BACKGROUND: Mental health disorders and sleep disturbances are significant public health challenges, especially among the elderly. Dietary fat quality has emerged as a critical regulator of sleep and mental well-being. This study aimed to investigate the association between fat quality and sleep/mental health outcomes in elderly individuals, considering gender-specific interactions. METHODS: This cross-sectional study included 398 Iranian elderly individuals aged 65-85 years with sleep disturbances and mental health concerns. Dietary intake was evaluated using a validated semi-quantitative Food Frequency Questionnaire (FFQ). Psychological health, sleep quality, and mood were assessed using the Depression, Anxiety, and Stress Scale-21 (DASS-21), the Pittsburgh Sleep Quality Index (PSQI), and the Profile of Mood States (POMS) questionnaire, respectively. Fat quality was assessed using the Fat Quality Index (FQI), cholesterol/saturated-fat index (CSI) and Omega-3:6 ratio. RESULTS: The study population consisted of 217 women and 181 men with a mean age of 63.31 ± 3.62 years. In the fully adjusted model, higher FQI was associated with lower anxiety risk and higher depression risk. The higher omega-3 to omega-6 ratio was linked to better sleep quality and lower depression risk, but higher anxiety risk. Higher CSI was associated with better sleep quality, higher anxiety risk and higher stress. Gender interactions were evident across various outcomes and fat quality indicators with sleep quality influenced by the omega-3/omega-6 ratio and CSI; mood by FQI and CSI; depression by FQI and CSI; anxiety by the omega-3/omega-6 ratio, FQI, and CSI; and stress showed interactions with all three indicators. CONCLUSIONS: Fat quality indicators exhibit complex and gender-dependent associations with mental health and sleep outcomes in older adults. While higher FQI appears protective against anxiety, it may elevate depression risk. A favorable omega-3/omega-6 ratio supports sleep and reduces depression risk but may increase anxiety. Elevated CSI correlates with improved sleep yet heightened anxiety and stress. These findings underscore the nuanced role of dietary fat composition in psychological well-being and sleep, highlighting the importance of personalized nutritional strategies.