Effects of a multi-vitamin/mineral supplement on cognitive function and fatigue during extended multi-tasking.

OBJECTIVES: A significant minority of the population consume multi-vitamins/minerals for their putative health benefits, including potentially beneficial effects on cognitive performance, fatigue and mood. The current study investigated the effect of supplementation with a multi-vitamin/mineral on fatigue and cognitive function in healthy females. METHODS: In this placebo-controlled, double blind, randomized, parallel groups trial the effect of a multi-vitamin/mineral (Supradyn) was assessed in 216 females aged 25-50 years. Participants attended the laboratory before and 9 weeks after commencing treatment. During both visits cognitive function and the modulation of task related mood/fatigue were assessed in two discrete 20-min assessment periods during which participants completed a four-module version of the Multi-Tasking Framework. RESULTS: Those in the vitamin/mineral group exhibited an attenuation of the negative effects of extended task completion on mood/fatigue. Multi-tasking performance for this group was also improved in terms of accuracy across all tasks, and on two of the individual tasks (Mathematical Processing and Stroop) in terms of both faster and more accurate responses. Analysis of a subsection (N = 102) demonstrated significant reductions in homocysteine levels following the vitamins/mineral supplement. CONCLUSIONS: These findings suggest that healthy members of the general population may benefit from augmented levels of vitamins/minerals via direct dietary supplementation.

Effects of resveratrol on cerebral blood flow variables and cognitive performance in humans: a double-blind, placebo-controlled, crossover investigation.

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.