Researchers say eating five portions of fruits and vegetables daily could reduce older adults' dementia risk.
In a study published in the journal Age and Ageing, researchers found that eating at least three portions of vegetables and two servings of fruits daily was associated with lower risk of dementia in older adults.
The World Health Organization (WHO) recommend that adults should consume at least 400 grams of fruits and vegetables daily - the equivalent to around five servings - in order to improve overall health and lower the risk of chronic diseases, such as heart disease and cancer.
Previous research has indicated that fruit and vegetable intake may also reduce the risk of Alzheimer's disease and other dementias, but the precise amounts that should be consumed to pose such benefits have been unclear.
For this latest study, co-author Linda Lam - of the Department of Psychiatry at the Chinese University of Hong Kong - and colleagues set out to investigate whether adhering to the five-a-day recommendation is associated with reduced dementia risk.
Lower dementia risk for adults who ate at least five-a-day
The researchers came to their findings by analyzing the health and diet of 17,700 older Chinese adults.
All adults were free of dementia at study baseline. The researchers followed the participants for an average of 6 years to see whether they developed the condition, and whether dementia development might be associated with fruit and vegetable intake.
Compared with adults who did not adhere to WHO recommendations for fruit and vegetable intake, adults who consumed three servings of vegetables and two servings of fruits daily were found to be at lower risk of dementia development over 6 years.
Dementia risk was further reduced for adults who consumed an additional three portions of vegetables each day, the team reports.
The results remained after accounting for a number of confounding factors, including age, smoking status, and the presence of other chronic diseases.
Findings highlight importance of fruit and veg intake for older adults
The study was not designed to pinpoint the reasons why fruits and vegetables might lower dementia risk, but the researchers speak of one hypothesis.
They explain that oxidativestress - an imbalance between free radical production and the body's ability to counteract the toxic effects - and inflammation is believed to play a role in dementia.
Further research is needed to explore precisely how fruits and vegetables might lower dementia risk, but this current study sheds light on how much we need to consume to reap the rewards.
"The findings of our study not only highlight the importance of consuming both fruits and vegetables in dementia prevention among older people, but also provide some insight into the daily amount of fruits and vegetables required for cognitive maintenance.
As a public health promotion strategy, the need for a balanced diet on cognitive health should be duly emphasized in the older population."