Grape juice boosts memory in healthy adults
The research was led by Louise Dye, PhD, a professor of Nutrition and Behavior at the University of Leeds medical college. The researchers recruited 25 healthy mothers between the ages of 40 and 50 years old. They were each mothers of younger children and also had a job working more than 30 hours a week.
In other words, they were busy women. They were raising kids and held down full time jobs.
At the beginning of the study, each of the women were tested for cognition and spatial memory tasks using a battery of cognitive tests. These tested the women’s mental executive function, cognitive attention, mood along with verbal and spatial memory. The researchers also tested the women’s blood pressure.
Furthermore, most of the women were also given a driving test in a computer simulator at the university. During this 25 minute simulator – called the driving performance assessment – the operator had to follow the car ahead. The driving simulator tested spatial memory and response time.
After their tests, half the women drank 12 ounces of concord grape juice each day for twelve weeks. The rest of the women drank a juice drink that looked and tasted similarly.
The women were tested again after six weeks and again after twelve weeks (about three months). The researchers found that the women who drank the purple grape juice had significantly higher cognitive scores than those women who drank the placebo juice each day.
The researchers found that the women who drank the grape juice had significant improvements in immediate spatial memory and driving performance. This was compared to the beginning of the study and compared to the placebo group.
The researchers concluded:
“Cognitive benefits associated with the long-term consumption of flavonoid-rich grape juice are not exclusive to adults with mild cognitive impairment. Moreover, these cognitive benefits are apparent in complex everyday tasks such as driving.”
How did the grape juice increase cognition?
The researchers tested the grape juice and found that each twelve ounce glass of grape juice given to the women contained 777 milligrams of total polyphenols. Polyphenols are antioxidant-rich plant compounds that include resveratrol and others – also contained within a class of compounds called flavonoids.
Polyphenol flavonoids are produced by plants as part of their immune defense system. They produce these to counteract and prevent attack by bacteria, fungi and other invaders. They also help protect the plant against damage from the sun’s radiation – or other environmental threats.
For this reason, flavonoids also confer their protective properties upon humans in the form of helping keep the brain nourished.
Dr. Nye explains this mechanism:
“The cognitive benefits are most associated with the flavonoids present in Concord grape juice – the plant nutrients that give Concord grapes their signature purple color. Numerous other studies have shown that Concord grape polyphenols are also associated with improving blood flow so it’s conceivable that increased blood flow to the brain could be the mechanism at play here.”
In fact, this and other research has found that the cognitive effects of grape’s polyphenols will persist. The researchers certainly found that the effects were maintained through the study period. They also added:
“Effects may persist beyond the cessation of flavonoid consumption.”
What about resveratrol?
Resveratrol is another potent phenol within grapes. While resveratrol wasn’t discussed in particular in the study, the cognitive result was gained from the grape juice, and concord grapes can contain resveratrol.
That is, assuming the grapes were challenged with fungi and grown in the right environment. The reality is, not every red or purple grape will contain resveratrol. Thus not all red/purple grape juice and red/purple wine will contain resveratrol either. Rather, red and purple grapes that have been exposed to the right environmental challenges will produce resveratrol.
Furthermore, other research has shown that resveratrol also increases cognition.
Resveratrol is a stilbenoid. The highest content of resveratrol itself is found in the skin of red or purple grapes, along with raspberries, blueberries, blackberries and mulberries – again challenged in the right environment.
This means that whole foods or juices of any of these fruits will contain the most resveratrol content. Because the skins have the highest content.
While red wine has been touted as the best source of resveratrol, research has illustrated that grape juice can contain similar amounts. But resveratrol is most available in whole fruits because these contain the skins. It is not a product of wine-making.
Other research confirms purple grape juice’s memory benefits
This is not the first study to show that concord grape juice improves memory. And grapes don’t just boost memory among the healthy. They also can help those with impaired memory or declining memory.
A 2010 study from the University of Cincinnati – published in the British Medical Journal Lancet – tested 12 adults with mild cognitive decline.
Here again, half the adults drank concord grape juice for 12 weeks and the other half drank a similar-tasting drink. Here again, the researchers found significant increases in verbal and spatial memory recall among the grape juice group.
Another study from the University of Cincinnati two years later found similar results. This study also tested older adults with memory decline. But this study tested the adults for four months. The results were the same, however: A significant increase in memory tasking. The researchers also did brain scans and found among the grape juice drinkers greater activation in the front and posterior regions of the right brain hemispheres – linked to memory tasking.
Whole versus Juice
From these studies we find that drinking 100% grape juice is a great strategy for getting these healthy polyphenols into the diet. However, my only concern is the blood sugar spike of drinking grape juice by itself.
Eating fresh purple or red grapes would be an even better strategy in my opinion. Or drinking them blended up in a smoothie. But barring that, I would suggest that the 100% concord grape juice is added to a smoothie that has other fresh fruits in it – at least, say, some apples and bananas. These will help slow and time the release of blood sugar.
Barring that, drinking the grape juice with some food containing natural fiber otherwise would be great, in my opinion.
REFERENCES:
Lamport DJ, Lawton CL, Merat N, Jamson H, Myrissa K, Hofman D, Chadwick HK, Quadt F, Wightman JD, Dye L. Concord grape juice, cognitive function, and driving performance: a 12-wk, placebo-controlled, randomized crossover trial in mothers of preteen children. Am J Clin Nutr. 2016 Mar;103(3):775-83. doi: 10.3945/ajcn.115.114553.
Krikorian R, Nash TA, Shidler MD, Shukitt-Hale B and Joseph JA. Concord grape juice supplementation improves memory function in older adults with mild cognitive impairment. Br J Nutr. 2010. 103(5):730-734.
Krikorian R, Boespflug EL, Fleck DE, Stein AL, Wightman JD, Shidler MD and Sadat-Hossieny S. Concord grape juice supplementation and neurocognitive function in human aging. J Agric Food Chem. 2012. 60(23):5736-5742.