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The potentially beneficial effects of pomegranate polyphenols on memory is currently under investigation at the UCLA Longevity Centre, California, in collaboration with the University of California and POM Wonderful LLC. Pomegranates are a rich source of antioxidants and, as such, have been researched for their potential health benefits. Now, pomegranates are being researched for their beneficial effects on memory, and their potential to delay the onset, or slow the progression, of Alzheimer’s disease.

Alzheimer’s disease is the most common form of dementia, accounting for 50-80% of all cases. Alzheimer’s is a slow progressing disease that adversely effects memory, thinking, and ultimately, behaviour. Symptoms of Alzheimer’s can manifest as early as ages 40-50, but more often in those over the age of 65. There is no cure for Alzheimer’s disease, only treatments that are able to temporarily attenuate the progression of the disease. Research focus remains on strategies to prevent or delay its onset and/or halt disease progression.

Some of the super foods that are reported to contain the highest levels of free-radical fighting polyphenols are: red wine, blueberries, and green tea. Pomegranates, however, contain more polyphenols than all three, with six times the amount of polyphenols in pomegranates than the amount found in green tea.

The polyphenols found in pomegranates include punicalagins and ellagic acid. Punicalagins are the major polyphenols present in pomegranates and are believed to be primarily responsible for the major health benefits of the fruit. However, it is likely that a synergistic interaction between more than one polyphenol is able to exert such beneficial effects. Punicalagins are water soluble and are therefore easily absorbed by the body. The metabolites of punicalagins are also potent antioxidants and have been detected in the body up to 48 hours after consumption.

The clinical trials investigating the effects of pomegranate polyphenols on memory stem from preclinical studies conducted in mouse models of Alzheimer’s disease.  In these studies, pomegranate polyphenols have demonstrated anti-inflammatory activity in the brains of mice who were fed pomegranate extract. Mice who received pomegranate supplements in their drinking water had a reduced accumulation of amyloid β peptide-containing plaques in their brain, which are a defining feature of the Alzheimer’s disease brain. In addition, studies have shown that mice receiving pomegranate supplementation had an improvement in spatial learning and memory-related tasks compared to mice who did not receive pomegranate supplements.

The results seen in mouse models of Alzheimer’s disease suggest that pomegranate polyphenols could also have beneficial effects in the human brain. Can pomegranate polyphenols improve cognitive abilities, delay the onset and/or slow the progression of Alzheimer’s disease in humans? To answer this there are now two randomized, double-blind studies enrolling healthy volunteers between the ages of 50-75 years. In one study, participants will take either a 1000mg pomegranate polyphenol extract capsule or a placebo control capsule. In the other study, participants will drink 8 ounces of pomegranate juice daily or a placebo juice that tastes the same as the pomegranate juice but contains only the same vitamins and minerals, without any of the pomegranate polyphenols. The volunteers for the study will be comprised of 212 people aged between 50-75 years who have no history of Alzheimer’s disease, with normal or mild cognitive impairment. The volunteers will have an initial clinical assessment consisting of memory tests, neuropsychological assessment, MRI, and blood tests that will determine genetic risk of Alzheimer’s disease and any other neurodegenerative memory disorders. Following the initial screening, the volunteers will begin their supplementation with pomegranate daily, or placebo control. A subsequent memory test will be given after one month and another neuropsychological assessment will be given at six months. Upon completion of the study (at 12 months) there will be another neuropsychological assessment and further blood tests.

The primary outcome measure for the studies will be improved cognitive performance, and the secondary outcome measure will be the correlation between cognitive change and genotype. Based on the results of the previous animal studies, the investigators expect that the participants who are in the pomegranate treatment group will have better cognitive performance compared to participants taking the placebo. It is hypothesized that cognitive decline and response to treatment will also be dependent on the genetic risk for Alzheimer’s disease.

The powerful activity of pomegranate polyphenols has led to the design of several other clinical trials investigating effects on infertility, ageing, cancer, and diabetes. Should the results of these studies return as predicted, there may be many more studies in the future to assess the potential health benefits of this super fruit.

 

 

Alzheimer’s fact sheet. Available from: http://www.alz.org/ Last Accessed April 1, 2014.

Hartman RE, Shah A, Fagan AM, Schwetye KE, Parsadanian M, Schulman RN, Finn MB, Holtzman DM. “Pomegranate juice decreases amyloid load and improves behavior in a mouse model of Alzheimer’s disease.”Neurobiol Dis.2006 Dec;24(3):506-15.

Rojanathammanee L, Puig KL, Combs CK. “Pomegranate polyphenols and extract inhibit nuclear factor of activated T-cell activity and microglial activation in vitro and in a transgenic mouse model of Alzheimer disease.”J Nutr. 2013 May;143(5):597-605.

Clinicaltrials.gov “Pomegranate Extract and Memory” Available from: http://www.clinicaltrials.gov/ct2/show/NCT01950221?term=pomegranate+alzheimer&rank=3Last Accessed: April 1, 2014.

Clinicaltrials.gov “Pomegranate Juice and Memory: Available from: http://www.clinicaltrials.gov/ct2/show/NCT02093130?term=pomegranate+alzheimer&rank=1Last Accessed: April 1, 2014.

Image courtesy of adamr / FreeDigitalPhotos.net

 

Written by Deborah Tallarigo, PhD

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