The Depression-Fighting Power of Fruits and Vegetables

A groundbreaking study using data from over 3,400 twins across four countries suggests that higher fruit and vegetable consumption is linked to reduced depression in adults aged 45 and older. The research, conducted by the Centre for Healthy Brain Ageing (CHeBA) at UNSW Sydney and published in Scientific Reports, highlights the critical role of nutrition in promoting mental health as people age.

The longitudinal study spanned 11 years and analyzed twins from Australia, Denmark, Sweden, and the U.S., all part of the Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium. It found that individuals with higher intakes of fruits and vegetables reported fewer depressive symptoms over time.

Lead author and post-doctoral fellow Dr. Annabel Matison noted, “The findings present another argument for increasing fruit and vegetable intake in adults over 45 years of age.”

Twin Studies: A Unique Approach

One of the most significant strengths of the research lies in its twin study design. Twins share 50–100% of their genetic makeup and, if raised together, experience the same early life environment. This unique framework allows researchers to isolate the effects of diet on depression from other confounding factors such as genetics or socioeconomic background.

Dr. Karen Mather, co-author and leader of CHeBA's Genomics and Epigenomics Group, emphasized this advantage, stating, “Twin designs can help address the issue of unwanted factors, like early-life socioeconomic status, influencing the results.”

The study gathered data from four twin research programs: the Older Australian Twins Study, Minnesota Twin Study of Adult Development and Aging, Middle Age Danish Twins Study, and Swedish Adoption/Twin Study of Aging. All participants were over 45 at baseline and provided information on their fruit and vegetable intake as well as depression symptoms at multiple points over the study period.

Dietary Intake and Mental Health

Low fruit intake in the study was defined as 0.3 servings per day, while low vegetable intake was 0.5 servings per day. Conversely, high intake equated to 2.1 servings of fruit and 2.0 servings of vegetables daily. Despite being categorized as "high," these levels still fell short of the World Health Organization’s (WHO) recommendation of five servings per day.

The researchers attribute the positive effects of fruits and vegetables on mental health to their high levels of dietary fiber, vitamins, and micronutrients. These components not only support overall physical health but also have profound impacts on the gut microbiome, oxidative stress, and inflammation—factors closely linked to depression.

Implications for Mental Health

Depressive disorders are a significant burden on adults over 55, ranging from mild forms that impair quality of life to severe cases of major depressive disorder. Research shows that individuals with major depression exhibit elevated levels of pro-inflammatory and oxidative stress markers and lower antioxidant levels compared to healthy individuals.

The study's findings underscore the potential of simple dietary interventions to alleviate depressive symptoms. While the results are promising, they also highlight a gap in meeting global dietary recommendations.

Reference:

1. Annabel P. Matison et al, Longitudinal associations between fruit and vegetable intakes and depressive symptoms in middle-aged and older adults from four international twin cohorts, Scientific Reports (2024). DOI: 10.1038/s41598-024-79963-2

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