A compound found in common foods such as red grapes and peanuts may help prevent age-related decline in memory, according to new research. Dr Ashok Shetty, a professor in the department of molecular and cellular medicine and director of neurosciences at the Institute for Regenerative Medicine, Texas A&M Health Science Centre College of Medicine, has been studying the potential benefit of resveratrol, an antioxidant that is found in the skin of red grapes, as well as in red wine, peanuts and some berries.
Resveratrol has been widely touted for its potential to prevent heart disease, but Shetty and his team believe it also has positive effects on the hippocampus, an area of the brain that is critical to functions such as memory, learning and mood. Because both humans and animals show a decline in cognitive capacity after middle age, the findings may have implications for treating memory loss in the elderly. Resveratrol may even be able to help people afflicted with severe neurodegenerative conditions such as Alzheimer’s disease.
In the study, Shetty and his team reported that treatment with resveratrol had apparent benefits in terms of learning, memory and mood function in aged rats. "The results of the study were striking," Shetty said. "They indicated that for the control rats who did not receive resveratrol, spatial learning ability was largely maintained but ability to make new spatial memories significantly declined between 22 and 25 months. By contrast, both spatial learning and memory improved in the resveratrol-treated rats."
Shetty said neurogenesis approximately doubled in the rats given resveratrol compared to the control rats. The resveratrol-treated rats also had significantly improved microvasculature, indicating improved blood flow, and had a lower level of chronic inflammation in the hippocampus. "The study provides novel evidence that resveratrol treatment in late middle age can help improve memory and mood function in old age," Shetty said.
Another study by Oregon State University researchers also found that drinking red grape juice or wine – in moderation – could improve the health of overweight people by helping them burn fat better. The findings suggest that consuming dark-coloured grapes, whether eating them or drinking juice or wine, might help people better manage obesity and related metabolic disorders such as fatty liver.
Neil Shay, a biochemist and molecular biologist in OSU's College of Agricultural Sciences, was part of a study team that exposed human liver and fat cells grown in the lab to extracts of four natural chemicals found in Muscadine grapes, a dark-red variety native to the southeastern US. One of the chemicals, ellagic acid, proved particularly potent: It dramatically slowed the growth of existing fat cells and formation of new ones, and it boosted metabolism of fatty acids in liver cells.
These plant chemicals are not a weight-loss miracle, cautions Shay. "We didn't find, and we didn't expect to, that these compounds would improve body weight," he said. But by boosting the burning of fat, especially in the liver, they may improve liver function in overweight people. "If we could develop a dietary strategy for reducing the harmful accumulation of fat in the liver, using common foods like grapes," Shay said, "that would be good news.”
The study, which Shay conducted with colleagues at the University of Florida and University of Nebraska, complements work with mice he leads at his OSU laboratory. Some of the mice were fed a normal diet of "mouse chow," as Shay calls it, containing 10% fat. The rest were fed a diet of 60% fat – the sort of unhealthy diet that would pile excess pounds on a human frame. "Our mice like that high-fat diet," said Shay, "and they over-consume it. So they're a good model for the sedentary person who eats too much snack food and doesn’t get enough exercise." The grape extracts, scaled down to a mouse's nutritional needs, were about the equivalent of one and a half cups of grapes a day for a person. "The portions are reasonable," said Shay, "which makes our results more applicable to the human diet."
Over a 10-week trial, the high-fat-fed mice developed fatty liver and diabetic symptoms – "the same metabolic consequences we see in many overweight, sedentary people," Shay said. But the chubby mice that got the extracts accumulated less fat in their livers, and they had lower blood sugar, than those that consumed the high-fat diet alone. Ellagic acid proved to be a powerhouse in this experiment, too, lowering the high-fat-fed mice's blood sugar to nearly the levels of the lean, normally fed mice.
When Shay and his colleagues analysed the tissues of the fat mice that ate the supplements, they noted higher activity levels of PPAR-alpha and PPAR-gamma, two proteins that work within cells to metabolise fat and sugar. Shay hypothesises that the ellagic acid and other chemicals bind to these PPAR-alpha and PPAR-gamma nuclear hormone receptors, causing them to switch on the genes that trigger the metabolism of dietary fat and glucose. Commonly prescribed drugs for lowering blood sugar and triglycerides act in this way, Shay said.
[link url="http://news.tamhsc.edu/?post=compound-found-in-grapes-red-wine-may-help-reverse-memory-loss"]Texas A&M Health Science Centre College of Medicine press release[/link]
[link url="http://news.tamhsc.edu/?post=compound-found-in-grapes-red-wine-may-help-reverse-memory-loss"]Scientific Reports abstract[/link]
[link url="http://oregonstate.edu/ua/ncs/archives/2015/feb/another-reason-drink-wine-it-could-help-you-burn-fat"]Oregon State University press release[/link]
[link url="http://www.jnutbio.com/article/S0955-2863(14)00208-3/abstract"]The Journal of Nutritional Biochemistry abstract[/link]