The glycaemic effects of single doses of Panax ginseng in young healthy volunteers

The results of two acute placebo-controlled, double-blind cross-over studies assessing the effect of Panax ginseng (G115) on blood glucose levels are reported. In study 1, thirty participants received three treatments: placebo; 200 mg G115; 400 mg G115. In study 2, twenty-seven participants received four treatments: placebo (0 mg ginseng and 30 mg saccharin); ginseng (200 mg ginseng and 30 mg saccharin); placebo–glucose (0 mg ginseng and 25 g oral glucose); ginseng–glucose (200 mg ginseng and 25 g oral glucose). Blood glucose levels were measured at baseline (at 09.00 hours after an overnight fast) and then 60, 90 (study 1 only) and 120 min post-dose. Both studies demonstrated that G115 alone significantly lowers fasting blood glucose levels. Conversely, in study 2 there was a significant drink × ginseng interaction suggesting opposing glycaemic effects of ginseng under fasting and raised blood glucose conditions. These data have implications for the use of ginseng in individuals with poor gluco-regulation

B vitamins and cognitive performance in older adults: Review

A copious amount of scientific scrutiny has been dedicated to documenting typical and atypical human ageing, with a substantial body of work focusing upon the impact of lifestyle choices. One such lifestyle choice is that of diet and, in particular, micronutrient ingestion. Epidemiological studies have reported positive associations between B vitamin status and cognitive function, including negative associations between biological markers (i.e., homocysteine) of dysregulated one-carbon metabolism and cognitive function. This has led to a surge of randomised control trials (RCTs) investigations into B vitamin therapy. However, results have continuingly failed to show beneficial behavioural effects. Despite this, results reliably show treatment-related increases in B vitamin level and decreases in homocysteine level—both of which have been identified as risk factors for atypical ageing. In this paper we argue that it would be premature to conclude that B vitamin therapy has no potential and that more research is needed to systematically investigate the optimal dose, the therapeutic “window,” and individual differences in therapy responders and nonresponders. We start with a brief look at one-carbon metabolism and then consider the evidence from epidemiological studies and RCTs in relation to three specific B vitamins: folic acid (B9), pyridoxine (B6), and cobamides (B12)

Neurocognitive and gluco-regulatory effects of Panax ginseng

Complementary and Alternative Medicine (CAM) has long been used in the Far East to aid in the recovery and prevention of illness. Ginseng, an over-the-counter herbal product in the UK, is amongst these herbal CAMs currently available to the general public. Ginseng is renowned for its rejuvenating properties and its purported ability to aid cognitive function and well-being. Despite the huge global market for ginseng there is little in the way of human research, utilising standardised ginseng extracts and well controlled methodology to support many of these claims. Additionally, ginseng's underlying mechanisms of action are poorly understood. The present thesis documents 5 double-blind, placebo-controlled, cross-over trials investigating the effects of Panax ginseng, following acute and chronic ingestion, on behaviour, mood and indices of glucose regulation in young healthy volunteers. The results of the five studies making this thesis suggest that both acute and chronic dosing with Panax ginseng is capable of modulating mood and cognitive performance in healthy young volunteers. Chapters 2 and 3 also demonstrate, for the first time, Panax ginseng's ability to modulate blood glucose levels following a single acute dose in overnight fasted healthy volunteers. In chapters 2 and 3, significant reductions in blood glucose levels and concomitant improvements in mental arithmetic (working memory) performance were reported. Chapter 4 revealed for the first time Panax ginseng's positive effects on traditional measures of working memory, thus posing the suggestion that previous failures to report working memory effects (using traditional working memory tasks) may have been due to poor task selection. Chapter 5 revealed an unexpected superimposed relationship between chronic and acute ingestion of Panax ginseng. The pattern of results suggests that following chronic dosing, an acute dose can further modulate cognition and mood (suggestive of a psychological dependence). The final chapter documents a different profile of cognitive and mood effects following a non-standardised Panax ginseng extract, thus highlighting the need for caution when generalising results across ginseng types and beyond the specific parameters of the methodologies utilised in any given study. Methodological differences between studies may go some way in explaining the inconsistent data patterns reported between studies, research groups and ginseng extracts. These data further highlight the need for well-controlled studies utilising standardised ginseng extracts and the need for the integration of 'theory driven' research in order to fractionate any behavioural effect. Such methodologies will inevitably lead to greater consistency between behavioural studies, at least in the first instance within the restricted population of volunteers utilised in the present thesis

DHA-rich oil modulates the cerebral haemodynamic response to cognitive tasks in healthy young adults: a near IR spectroscopy pilot study

The impact of dietary n-3 PUFA on behavioural outcomes has been widely researched; however, very little attention has been given to their impact on brain functioning in physiological terms. A total of twenty-two healthy adults took part in this double-blind, placebo-controlled study, wherein the cerebral haemodynamic effects of 12 weeks of daily dietary supplementation with either 1 g DHA-rich or 1 g EPA-rich fish oil (FO) or placebo (1 g olive oil) were assessed. Relative changes in the concentration of oxygenated Hb (oxy-Hb) and deoxygenated Hb were assessed in the prefrontal cortex using near IR spectroscopy (NIRS) during the performance of four computerised cognitive tasks. Supplementation with DHA-rich FO, in comparison with placebo, resulted in a significant increase in the concentrations of oxy-Hb and total levels of Hb, indicative of increased cerebral blood flow (CBF), during the cognitive tasks. In comparison, no effect on CBF was observed following supplementation with EPA-rich FO, where concentration changes in the chromophores followed the same pattern as placebo. These encouraging pilot data warrant further application of NIRS in this area

Panax ginseng has no effect on indices of glucose regulation following acute or chronic ingestion in healthy volunteers

In the absence of effective pharmacotherapy for diabetes there has been an increase in the use of, and research into, alternative treatment strategies. These include exercise, dietary interventions and the use of supplements including extracts of ginseng. Two separate, placebo-controlled, double-blind, cross-over studies investigating the effects of chronic ingestion of Panax ginseng (study 1 used G115, study 2 used Cheong Kwan Jang) on glycated Hb (HbA1c; study 1, n 18; study 2, n 11), fasting plasma insulin (study 1, n 17; study 2, n 12), fasting plasma glucose and postprandial response (following breakfast) (study 1, n 23; study 2, n 14) in healthy volunteers are reported. In both studies it was found that Panax ginseng had no effect on any gluco-regulatory parameter investigated. These results are not consistent with those reported for a diabetic sample (albeit using slightly different outcomes). These results would suggest that chronic use of Panax ginseng by non-diabetic individuals will have little long-term effect on glucose regulation. The benefits to glucose regulation associated with long-term ginseng use may only be present in populations with compromised glucose control; however, further research is needed to confirm such a speculation

Neurocognitive and gluco-regulatory effects of Panax ginseng

Complementary and Alternative Medicine (CAM) has long been used in the Far East to aid in the recovery and prevention of illness. Ginseng, an over-the-counter herbal product in the UK, is amongst these herbal CAMs currently available to the general public. Ginseng is renowned for its rejuvenating properties and its purported ability to aid cognitive function and well-being. Despite the huge global market for ginseng there is little in the way of human research, utilising standardised ginseng extracts and well controlled methodology to support many of these claims. Additionally, ginseng's underlying mechanisms of action are poorly understood. The present thesis documents 5 double-blind, placebo-controlled, cross-over trials investigating the effects of Panax ginseng, following acute and chronic ingestion, on behaviour, mood and indices of glucose regulation in young healthy volunteers. The results of the five studies making this thesis suggest that both acute and chronic dosing with Panax ginseng is capable of modulating mood and cognitive performance in healthy young volunteers. Chapters 2 and 3 also demonstrate, for the first time, Panax ginseng's ability to modulate blood glucose levels following a single acute dose in overnight fasted healthy volunteers. In chapters 2 and 3, significant reductions in blood glucose levels and concomitant improvements in mental arithmetic (working memory) performance were reported. Chapter 4 revealed for the first time Panax ginseng's positive effects on traditional measures of working memory, thus posing the suggestion that previous failures to report working memory effects (using traditional working memory tasks) may have been due to poor task selection. Chapter 5 revealed an unexpected superimposed relationship between chronic and acute ingestion of Panax ginseng. The pattern of results suggests that following chronic dosing, an acute dose can further modulate cognition and mood (suggestive of a psychological dependence). The final chapter documents a different profile of cognitive and mood effects following a non-standardised Panax ginseng extract, thus highlighting the need for caution when generalising results across ginseng types and beyond the specific parameters of the methodologies utilised in any given study. Methodological differences between studies may go some way in explaining the inconsistent data patterns reported between studies, research groups and ginseng extracts. These data further highlight the need for well-controlled studies utilising standardised ginseng extracts and the need for the integration of 'theory driven' research in order to fractionate any behavioural effect. Such methodologies will inevitably lead to greater consistency between behavioural studies, at least in the first instance within the restricted population of volunteers utilised in the present thesis.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The effects of chronic trans-resveratrol supplementation on aspects of cognitive function, mood, sleep, health and cerebral blood flow in healthy, young humans

Single doses of resveratrol have previously been shown to increase cerebral blood flow (CBF) with no clear effect on cognitive function or mood in healthy adults. Chronic resveratrol consumption may increase the poor bioavailability of resveratrol or otherwise potentiate its psychological effects. In this randomised, double-blind, placebo-controlled, parallel-groups study, a total of sixty adults aged between 18 and 30 years received either placebo or resveratrol for 28 d. On the 1st and 28th day of treatment, the performance of cognitively demanding tasks (serial subtractions, rapid visual information processing and 3-Back) (n 41 complete data sets) was assessed, alongside blood pressure (n 26) and acute (near-IR spectroscopy (NIRS)) and chronic (transcranial Doppler) measures of CBF (n 46). Subjective mood, sleep quality and health questionnaires were completed at weekly intervals (n 53/54). The results showed that the cognitive effects of resveratrol on day 1 were restricted to more accurate but slower serial subtraction task performance. The only cognitive finding on day 28 was a beneficial effect of resveratrol on the accuracy of the 3-Back task before treatment consumption. Subjective ratings of ‘fatigue’ were significantly lower across the entire 28 d in the resveratrol condition. Resveratrol also resulted in modulation of CBF parameters on day 1, as assessed by NIRS, and significantly increased diastolic blood pressure on day 28. Levels of resveratrol metabolites were significantly higher both before and after the day’s treatment on day 28, in comparison with day 1. These results confirm the acute CBF effects of resveratrol and the lack of interpretable cognitive effects