Is a plant-based diet effective to maintain a good psycho-affective status in old age? Results of a survey of a long-lived population from Sardinia

Background: Depression is common among the elderly, resulting in poor quality of life and elevated healthcare expenditure. Among other factors, dietary habits could also affect this condition, although the specific food patterns involved remain to be established. The present study aimed to assess the role of plant- versus animal-dominant foods consumption on the affective state of nonagenarians from a Sardinian population, Italy, well known for its longevity (Blue Zone). Methods: Data, including demographic, education, anthropometric parameters, monthly income, and comorbidity were recorded and analyzed. Symptomatic depression was assessed using the Geriatric Depression Scale (GDS) during a comprehensive home geriatric assessment; nutritional status was evaluated by a validated food frequency questionnaire. Results: A total of 200 elderly subjects living in the Sardinian Blue Zone (mean age 93.9 ± 3.9 years) participated in the study; symptomatic depression was present in 51% of the whole cohort and was more common among women. Multivariable logistic regression showed a significantly greater risk of depression in people consuming plantbased foods (OR = 1.42, 95% CI 1.04–1.93), whereas moderate animal-derived foods consumption was associated with a better affective state (OR = 0.79, 95% CI 0.62–0.98). Conclusions: These findings indicate that a more balanced diet, including animal-derived foods, instead of an exclusive plant-dominant diet, may be more appropriate in the elderly, and abstention from animal-based food intake should not be recommended in advanced age to prevent depression.