A growing body of evidence suggests that dietary habits, particularly higher consumption of fruits and vegetables, may be crucial in reducing the risk of depression.
New Insights from Global Research
New research led by Post Doctoral Fellow Annabel Matison from UNSW Sydney’s Centre for Healthy Brain Ageing (CHeBA) has addressed the significant gap in research on older adults and those in low- to middle-income countries.
“Compared with depression in younger adults, depression in older adults has a greater impact on physical performance and cognition, and is associated with lower quality of life and higher death rates,” says Matison. “Our aim with this study was to examine the associations between fruit and vegetable intake and depression in adults aged 45 years and older.”
Comprehensive and Diverse Study
Participants in the study were drawn from multiple regions across six continents, including the United States, Sweden, Brazil, Nigeria, Malaysia, and Australia. All data was collected and harmonised from ten longitudinal studies, with all groups part of the CHeBA-led Cohort Studies of Memory in an International Consortium (COSMIC).
The research, published in the *Journal of Affective Disorders*, assessed 7,801 community-based adults without depression. The study revealed a significant beneficial association between higher fruit intake and a lower risk of depression over a nine-year period.
“This interesting finding of a protective association between fruit intake and risk of depression demonstrates a need to place greater emphasis on diet in healthcare,” says Matison.
The Distinction Between Fruits and Vegetables
While the results suggested a benefit from vegetable intake, these findings were not statistically significant.
“The reason we found a beneficial relationship for fruit, but not vegetable intake, may be that vegetables are typically consumed cooked, which may impact their nutrient content, whereas fruit is generally consumed raw,” explains Matison.
Fruit and vegetable intake was self-reported via comprehensive food frequency questionnaires, short food questionnaires, or diet history. Depressive symptoms were assessed using validated measures, and depression was defined using validated cut-offs. The associations between baseline fruit and vegetable intakes and incident depression over a follow-up period of three to nine years were examined using the Cox regression method.
Future Directions
High levels of antioxidants, dietary fibre, and vitamins in fruits and vegetables may influence depression through numerous mechanisms, such as their role in reducing inflammation, oxidative stress, and impacting the gut microbiota. The evidence is particularly strong for citrus fruits and green leafy vegetables being associated with a lower risk of depression.
CHeBA Co-Director and co-author on the research, Professor Henry Brodaty, emphasised the importance of further research. “Future research considering the consumption of different types of fruits and vegetables using standardised measures and focusing on larger numbers of older adults is definitely warranted, particularly for low- and middle-income countries.”
“The extension of current research into the genes associated with dietary intake provides a promising avenue to influence the consumption of fruits and vegetables,” says Professor Brodaty. “We should also consider the types of fruits and vegetables consumed to better understand the relationships involved, and studies should be designed to provide more comparability across cohorts.”
