Dr Martha Morris, of Rush University Medical Centre in Chicago, led the study published in the journal Neurology.
Green leafy vegetables slow the ageing of the brain and help to preserve memory and other cognitive functions, USA researchers at the Medical Center of Rush University said in an article published on Neurology journal.
Her team analysed the eating habits of 960 people, with an average age of 81, who did not have dementia and tracked them for an average of 4.7 years.
The participants of the study completed food frequency questionnaires, which enquired about how often they ate certain foods in the past years.
Regular consumption of green leafy vegetables can reduce cognitive decline as per results of a new study. Those classed as eating the most green, leafy vegetables had between 1 and 2 servings each day.
"Consumption of approximately one serving per day of green leafy vegetables and foods rich in phylloquinone, lutein, nitrate, folate, α-tocopherol, and kaempferol may help to slow cognitive decline with aging", the authors write.
"Fruits and vegetables are a key component of a nutritionally balanced diet, but figures suggest that many of us struggle to eat our five-a-day". It also improves the overall health of the brain.
People who don't like the pungent green taste of kale can achieve the same effect with other leafy green vegetables, the researchers say.
Intake of primary nutrients and bioactives in green leafy vegetables is associated with slower cognitive decline, according to a study published online December 20 in Neurology.
However, Morris' study was observational, meaning there's only a correlation-nothing concrete-between how greens affect your brain. "There continues to be sharp increases in the percentage of people with dementia as the oldest age groups continue to grow in number".