Previous research has identified the benefits polyphenol-rich compounds have on neurocognitive function in older people. Here the research, led by Dr Lamport from the School of Psychology, University of Leeds, UK, has demonstrated for the first time that cognitive benefits associated with drinking grape juice extend beyond older adults.
Over the course of 12 weeks, the female participants were asked to undergo a series of tests that assessed their cognitive performance. One test was a 25-minute driving simulator challenge in which they were asked to match the speed and direction of a lead vehicle.
Subjects—consisting of 25 healthy, 40-50 year old working women with pre-teen children—who drank 355ml of Concord grape juice showed significant improvements in immediate spatial memory and driving performance when compared to those who drank the placebo (a grape-flavoured, sugar-sweetened drink).
In addition, there was evidence of a long-term effect of the grape juice that allowed participants to consistently maintain a better performance even when participants stopped drinking the grape juice.
The findings—presented at the recent biennial International Conference on Polyphenols & Health in Dijon, France in October—add to a growing body of polyphenol-based cognitive benefits.
“While more research is needed to add to this work, these new studies are promising, especially given the growing interest in the role of nutrition in cognitive wellbeing and the ongoing dialogue around beverages and health,” said Casey Lewis, Welch’s dietitian and health & nutrition lead.
More grape juice gains
Whilst grape juice is rich in polyphenols, it also contains natural sugar, which should be consumed in moderation. However, research has also suggested polyphenols may be able to mitigate glycaemic response by slowing down the absorption of these sugars when compared to a non-grape sweetened beverage.
In a study, also presented at the conference, pre-clinical results compiled by Dr Moser from the Department of Food Science at Purdue University, suggested that after drinking grape juice, blood sugar levels may rise less dramatically than would be expected, potentially aiding in blood glucose control as part of a daily health regimen.
Using an in vitro approach and a human intestinal cell model, grape juice polyphenols were assessed for their ability to inhibit starch digestion (α-amylase, α-glucosidase activity) and glucose/ fructose transport.
While the grape juice extracts (polyphenols and anthocyanins) exhibited a limited ability to inhibit α-amylase, all extracts showed modest inhibitory activity on α-glucosidases (6.2-11.5%; P<0.05).
Similarly the grape juice extracts reduced the transport of glucose and fructose by 10-38% by co-administration of the grape juice extracts compared to control. Specifically, transport of glucose was reduced by 26-38% when Concord and Niagara grape juices were being consumed compared to the control.
Research presented at congress ahead of publication at the biennial International Conference on Polyphenols & Health