Pomegranate Juice Allegedly Linked to Heightened Neurodegeneration in Parkinson’s Disease
University of Pittsburgh and Purdue University researchers have purportedly found that pomegranate juice (PJ) heightened neurodegeneration in an animal model of Parkinson’s disease (PD) by increasing nigrostriatal terminal depletion, dopamine neuron loss, the inflammatory response, and caspase activation. Victor Tapias, et al., “Pomegranate Juice Exacerbates Oxidative Stress and Nigrostriatal Degeneration in Parkinson’s Disease,” Neurobiology of Aging, May 2014. Designed to examine the beverage’s potential neuroprotective effects, the study instead suggested that the polyphenols present in pomegranate juice exacerbated the nigrostriatal degeneration of rats with a rotenone-induced syndrome similar to PD.
“Several studies have demonstrated the efficacy of different types of polyphenols to attenuate or block neuronal death in animal models of neurodegeneration,” reported the study’s authors. “Although differences between PD models could explain a lack of beneficial efficacy of PJ in the rotenone model, the question remains as to why PJ would exacerbate rotenone toxicity—similarly to melatonin. A possible answer could be related to misconceptions about the antioxidant properties of PJ; polyphenolic phytochemicals are considered double-edged swords in cellular redox status.”
In particular, the authors hypothesized that “the pro-oxidant nature of a large number of polyphenol compounds… may lead to an increase in lipid peroxidation, DNA damage, mitochondrial damage, and caspase-3 activation, and intracellular glutathione depletion and ROS [reactive oxygen species] scavenging enzyme inhibition.” Concluding that their data “provide novel, strong evidence for a pro-oxidant effect of PJ in a PD model,” they recommended further research “into the effects of PJ in neurodegeneration.”
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