Safety and Neuroprotective Efficacy of Palm Oil and Tocotrienol-Rich Fraction from Palm Oil: A Systematic Review.
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ABSTRACT: BACKGROUND:Several natural products have been reported to elicit beneficial effects against neurodegenerative disorders due to their vitamin E contents. However, the neuroprotective efficacy of palm oil or its tocotrienol-rich fraction (TRF) from the pre-clinical cell and animal studies have not been systematically reviewed. METHODS:The protocol for this systematic review was registered in "PROSPERO" (CRD42019150408). This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The Medical Subject Heading (MeSH) descriptors of PubMed with Boolean operators were used to construct keywords, including ("Palm Oil"[Mesh]) AND "Nervous System"[Mesh], ("Palm Oil"[Mesh]) AND "Neurodegenerative Diseases"[Mesh], ("Palm Oil"[Mesh]) AND "Brain"[Mesh], and ("Palm Oil"[Mesh]) AND "Cognition"[Mesh], to retrieve the pertinent records from PubMed, Scopus, Web of Science and ScienceDirect from 1990 to 2019, while bibliographies, ProQuest and Google Scholar were searched to ensure a comprehensive identification of relevant articles. Two independent investigators were involved at every stage of the systematic review, while discrepancies were resolved through discussion with a third investigator. RESULTS:All of the 18 included studies in this review (10 animal and eight cell studies) showed that palm oil and TRF enhanced the cognitive performance of healthy animals. In diabetes-induced rats, TRF and ?-tocotrienol enhanced cognitive function and exerted antioxidant, anti-apoptotic and anti-inflammatory activities, while in a transgenic Alzheimer's disease (AD) animal model, TRF enhanced the cognitive function and reduced the deposition of ?-amyloid by altering the expression of several genes related to AD and neuroprotection. In cell studies, simultaneous treatment with ?-tocotrienols and neurotoxins improved the redox status in neuronal cells better than ?- and ?-tocotrienols. Both pre-treatment and post-treatment with ?-tocotrienol relative to oxidative insults were able to enhance the survival of neuronal cells via increased antioxidant responses. CONCLUSIONS:Palm oil and its TRF enhanced the cognitive functions of healthy animals, while TRF and ?-tocotrienol enhanced the cognitive performance with attenuation of oxidative stress, neuroinflammation and apoptosis in diabetes-induced or transgenic AD animal models. In cell studies, TRF and ?-tocotrienol exerted prophylactic neuroprotective effects, while ?-tocotrienol exerted therapeutic neuroprotective effects that were superior to those of ?- and ?-tocotrienol isomers.
SUBMITTER: Ismail M
PROVIDER: S-EPMC7071496 | biostudies-literature | 2020 Feb
REPOSITORIES: biostudies-literature
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