Vitamin C intake, psychological distress and health outcomes in patients with heart failure

Abstract Background Patients with heart failure (HF) have lower dietary vitamin C intake than healthy adults, which may increase oxidative stress and worsen important patient-reported health outcomes (functional status and quality of life [QOL]). Patients with HF are more likely to have higher levels of psychological distress (anxiety and depressive symptoms). However, it is not known whether psychological distress is a link in the association of dietary vitamin C with health outcomes. Objective To examine the inter-relationships among dietary vitamin C intake, psychological distress (anxiety and depressive symptoms), and health outcomes (functional status and QOL) in patients with HF. Method We performed a secondary analysis of baseline data from 206 adults with HF (female: 33%, age: 61±12, NYHA class III/IV: 44%) with complete data on dietary vitamin C intake, anxiety, depressive symptoms, functional status, and QOL. Dietary vitamin C intake was assessed using a 4-day food diary and analyzed using the Nutrition Data System for Research software program. Low dietary vitamin C intake was defined as averaged daily intake below the estimated average requirement (EAR) from the Institute of Medicine of 75 mg/day for men and 60 mg/day for women. Anxiety was assessed using the Brief Symptom Inventory Anxiety subscale. Depressive symptoms were assessed using the Beck Depression Inventory II. Functional status was measured using the Duke Activity Status Index. Quality of life was measured using the Minnesota Living with Heart Failure Questionnaire. Linear regression was conducted using the PROCESS macro in SPSS. Results Eighty-four patients (41%) had low dietary vitamin C intake based on the EAR standard. In bivariate analyses, patients with low dietary vitamin C intake had higher levels of anxiety, depressive symptoms, poorer functional status, and worse QOL (all p <.005). In the mediation regression model, low dietary vitamin C intake was directly associated with higher levels of anxiety, but not with depressive symptoms. Depressive symptoms were directly associated with functional status and QOL. Dietary vitamin C intake was not directly associated with functional status or QOL. Low dietary vitamin C intake was indirectly associated with poor functional status through higher levels of anxiety and depressive symptoms (Figure 1). Similarly, low dietary vitamin C intake was indirectly associated with worse QOL (Figure 2). Conclusion Anxiety and depressive symptoms link the relationship between dietary vitamin C intake and functional status and between dietary vitamin C intake and QOL. Our findings highlight the importance of including interventions to enhance diet quality and psychological well-being as part of HF treatment to improve health outcomes.Vitamin C and functional statusVitamin C and quality of life