Eating plenty of fruit reduces the risk of depression in later life, according to new research. The 20-year study involving more than 13,000 participants showed that higher consumption of fruits – including oranges, tangerines and bananas – was associated with lower chances of depressive symptoms in old age.
Eating at least three servings of fruit a day in middle age reduced the likelihood of ageing-related depression by at least 21% compared to eating one or less daily portion, say scientists. Doctors worldwide have noted an increased prevalence of depressive symptoms among older adults – including depressed feelings, lack of pleasure and delayed cognitive processing – often accompanied by loss of appetite, insomnia, poor concentration, and increased fatigue as people live longer.
They say it is related to underlying neurodegenerative changes in the brain associated with ageing. The drive to keep older adults in good health has triggered extensive research into approaches that could prevent later-life depression.
Accumulating evidence has revealed the plausible role of dietary factors in protecting against depression in ageing. The new research, conducted by the Yong Loo Lin School of Medicine at the National University of Singapore, involved 13,738 participants from the Singapore Chinese Health Study that tracked participants through their mid-life to later life spanning around 20 years.
The research team found that participants who consumed higher quantities of fruit earlier in life exhibited a reduced likelihood of experiencing depressive symptoms later in life. The researchers studied a total of 14 fruits most commonly eaten in Singapore and found that the consumption of most fruits – including oranges, tangerines, bananas, papayas, watermelons, apple and honey melon – was associated with reduced likelihood of depression.
They say the high levels of antioxidants and anti-inflammatory micronutrients in fruits – such as vitamin C, carotenoids and flavonoids – which have been shown to reduce oxidative stress and inhibit inflammatory processes in the body may affect the development of depression.
But consumption of vegetables was found to have no association with the likelihood of depressive symptoms. The researchers say their findings, published in the Journal of Nutrition, Health and Ageing, provide “valuable insights” into the potential benefits of eating sufficient fruit in mitigating depressive symptoms later in life.
Principal investigator Professor Koh Woon Puay, of NUS Medicine, said: “Our study underscores the importance of fruit consumption as a preventive measure against ageing-related depression. In our study population, participants who had at least three servings of fruits a day, compared to those with less than one serving a day, were able to reduce the likelihood of ageing-related depression significantly by at least 21%.”
“This can be achieved by eating one to two servings of fruits after every meal. We did not see any difference in our results between fruits with high and low glycemic index. Hence, for those with diabetes, they can choose fruits with low glycemic index that will not raise blood sugars as much as those with high index.”
At the initial stage of the study from 1993 to 1998, when participants were an average age of 51, they were asked to answer a questionnaire on how often they consumed a standard serving size of each food item daily, for 14 fruits and 25 vegetables. In 2014 to 2016, when participants were an average age of 73, depressive symptoms were examined using a standard test and 3,180 (23.1%) participants who reported having five or more symptoms were considered to have depression.
After adjusting for factors including medical history, smoking status, level of physical activity and sleep duration, the researchers found that higher consumption of fruits, but not vegetables, was associated with lower odds of depressive symptoms. Prof Koh said: “Our study aimed to examine the relationship of mid-life consumption of fruits and vegetables with the risk of depressive symptoms in late life.”
“Although other studies have also examined the associations of fruits and vegetables with risk of depression, there are inconsistencies in the results.”
She added: “These findings suggest that promoting fruit consumption for individuals in mid adulthood, typically defined as ages 40 to 65, could yield long-term benefits for their mental well-being at late adulthood beyond 65.”
The research team is now looking into the association of other modifiable behaviours – such as sleep duration, smoking and other dietary factors – with the mental health of older adults.