A small study, which saw 37 adults with an average age of 67 consume 500ml of orange juice daily for eight weeks, found they had an eight per cent overall improvement in cognitive function compared with a group who consumed a control drink.
At the beginning and end of the eight weeks their memory, reaction time and verbal fluency was measured by carrying out eight tests.
One of the tests of verbal memory required learning a list of words to be recalled immediately, and again after a 30-minute delay.
Researchers said an eight per cent improvement equates to remembering one more word from a shopping list of 15 items. Small improvements such as this over an eight-week period could translate into substantial improvements over the lifespan.
While the researchers are not recommending that people drink 500ml of orange juice every day, due to its high sugar content, they said their findings show that the constituents of orange juice could play an important role in providing brain-boosting nutrients as part of a healthy, balanced diet.
Co-author Dr Daniel Lamport, of the University of Reading's School of Psychology and Clinical Language Sciences, said orange juice is a major source of a group of naturally occurring plant phytochemicals known as flavonoids, and is particularly rich in a sub-class of flavonoids, known as flavanones.
Recent studies have shown that flavonoids may improve memory through the activation of signalling pathways in the hippocampus, a part of the brain that is associated with learning and memory.
He said with a rapidly ageing population and estimations that the number of persons aged 60 or over could triple by 2100, it is "imperative" that simple, cost-effective ways to improve cognitive function in old age are explored.
"Small, easily administered changes to the daily diet, such as eating more flavonoid-rich fruits and vegetables, have the potential to substantially benefit brain health," he said.