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April 29, 2010: by ResveratrolNews
A human study, conducted among adults in their 20s, shows that a single high-dose of resveratrol (250 or 500 milligram, 99% resveratrol, Biotivia) improves hemoglobin concentrations and delivery of oxygen to the brain, but did not improve “cognitive” (thinking) performance or allay mental fatigue. Researchers believe resveratrol activated nitric oxide gas which dilated (widened) blood vessels in the brain. The design and conclusions of study, conducted by British researchers, are brought into question because resveratrol is a copper chelator (key-lay-tor) and may over long-term use actually reduce hemoglobin levels and produce symptoms of fatigue and anemia. The higher (500 mg) dose used in this study was also shown in a prior animal experiment to slightly shorten lifespan. – Resveratrol News April 29, 2010
David O Kennedy, Emma L Wightman, Jonathon L Reay, Georg Lietz, Edward J Okello, Anthea Wilde and Crystal F Haskell
Am J Clin Nutr (March 31, 2010). doi:10.3945/ajcn.2009.28641
1 From the Brain PerformanceNutrition Research Centre Northumbria University Newcastle upon Tyne United Kingdom (DOK ELW JLR AWCFH)the School of Agriculture FoodRural Development Newcastle University Newcastle upon Tyne United Kingdom (GLEJO).
2 The research described herein was internally funded, and all materials were purchased on the open market.
3 Address reprint requests and correspondence to DO Kennedy, Brain,Performance and Nutrition Research Centre, Northumbria University, Newcastle, United Kingdom NE1 8ST.
Background: The many putative beneficial effects of the polyphenol resveratrol include an ability to bolster endogenous antioxidant defenses, modulate nitric oxide synthesis, and promote vasodilation, which thereby improves blood flow. Resveratrol may therefore modulate aspects of brain function in humans.
Objective: The current study assessed the effects of oral resveratrol on cognitive performance and localized cerebral blood flow variables in healthy human adults.
Design: In this randomized, double-blind, placebo-controlled, crossover study, 22 healthy adults received placebo and 2 doses (250 and 500 mg) of trans-resveratrol in counterbalanced order on separate days. After a 45-min resting absorption period, the participants performed a selection of cognitive tasks that activate the frontal cortex for an additional 36 min. Cerebral blood flow and hemodynamics, as indexed by concentration changes in oxygenated and deoxygenated hemoglobin, were assessed in the frontal cortex throughout the posttreatment period with the use of near-infrared spectroscopy. The presence of resveratrol and its conjugates in plasma was confirmed by HPLC after the same doses in a separate cohort (n = 9).
Results: Resveratrol administration resulted in dose-dependent increases in cerebral blood flow during task performance, as indexed by total concentrations of hemoglobin. There was also an increase in deoxyhemoglobin after both doses of resveratrol, which suggested enhanced oxygen extraction, that became apparent toward the end of the 45-min absorption phase and was sustained throughout task performance. Cognitive function was not affected. Resveratrol metabolites were present in plasma throughout the cognitive task period.
Conclusion: These results showed that single doses of orally administered resveratrol can modulate cerebral blood flow variables.