Fruit is a staple in many kitchens, and for good reason: its versatile, full of fibre and antioxidants, and makes a great on-the-go snack. It also could reduce your risk of depression, according to new research - if you're eating enough of it.
The study follows a growing body of evidence that suggests dietary behaviours - particularly a high intake of fruit and vegetables - could be important in reducing the risk of depression.
Depression is a major public health concern worldwide. According to the World Health Organization (WHO), an estimated 5 percent of adults suffer from depression globally, and approximately 280 million people have the disorder. Depression is about 50 percent more common among women than among men, and more than 75 percent of people in low-and-middle-income countries receive no treatment.
The new research, led by Post Doctoral Fellow Annabel Matison from the University of New South Wales Sydney's (UNSW) Centre for Healthy Brain Ageing (CHeBA), has for the first time addressed a gap in research regarding older adults aged 45 and over.
"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 rate," Matison said.
"Our aim with this study was to examine the associations between fruit and vegetable intake and depression in adults 45 years and older."
Participants in the study came from multiple regions across six continents, including the United States, Sweden, Brazil, Nigeria, Malaysia and Australia. The research, published in the Journal of Affective Disorders, assessed 7801 community-based adults without depression and revealed a beneficial association between higher fruit consumption 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 give a greater emphasis to diet in healthcare," Matison said.
Although the results also suggested a beneficial relationship between vegetable intake and a reduced risk of depression, it was not statistically significant, she added.
"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," she explained.
The participants self-reported their fruit and vegetable intake via a comprehensive food frequency questionnaire, a short food questionnaire or diet history. Depressive symptoms were assessed using "validated measures", the researchers said, while the Cox regression method was used to examine the relationships between intake and depression over a follow-up period of three to nine years.
It has been suggested that the high levels of antioxidants, dietary fibre and vitamins in fruit and vegetables may have a beneficial influence on depression through numerous mechanisms, such as their role in inflammation, oxidative stress and the gut microbiota, the researchers noted.
As the various fruits and vegetables all have different nutrient profiles, it also seems likely that different types may have differing impacts on the risk of depression. The study noted the evidence for citrus fruits and green leafy vegetables being associated with a lower risk of depression is particularly strong.
Professor Henry Brodaty, co-author and CHeBA co-director, said future research considering the consumption of different types of fruit and vegetables - and focusing on larger numbers of older adults - is warranted, particularly for low- and middle-income countries.
"The extension of current research being conducted into the genes associated with dietary intake provides a promising avenue to influence the intakes of fruit and vegetables," Professor Brodaty said.
"We should also consider the types of fruit and vegetables consumed to better understand the relationships involved and studies should be designed to provide more comparability across cohorts."
