Investigating the relationship between plant-based dietary protein indices and depression score in the elderly of Shiraz City: A cross-sectional study

Depression is an important and common disorder in the elderly. Plant-based dietary patterns are often considered "healthy" and associated with various health benefits. However, the association between plant-based dietary indices and depression is largely ambiguous. This cross-sectional study aimed to investigate the relationship between plant protein indices and depression in the elderly population. In this cross-sectional study, conducted on 80 elderly people living in Shiraz City, food intake information was collected using a 147-item food frequency questionnaire. Plant-based diet index (PDI), healthy PDI (hPDI), and unhealthy PDI (uPDI) were used to assess dietary patterns. Also, depression was evaluated using the Beck Depression questionnaire. A linear regression method in crude and 2 adjusted models was used to investigate the relationship between dietary indicators and depression. P < .05 was considered significant. Higher PDI and uPDI scores were related to lower intakes of vitamin B12 (P = .04, .03). Also, higher hPDI and uPDI scores were associated with lower saturated fatty acids intakes (P = .04, .01). A significant positive relationship between depression and hPDI was observed in both crude (P = .01), and adjusted (P = .01) models. While, for PDI and uPDI, no significant relationship was observed in any of the models. Plant-based dietary patterns could be possibly related to depression in the older population. However, the evidence is inconsistent and more investigations with larger sample sizes and appropriate designs are needed to clarify this relationship.