berrIes
Supporting Human Studies
Blueberry Supplementation Improves Memory in Older Adults (Krikorian et al, 2010)
This study investigated the effects of daily consumption of wild blueberry juice in a sample of nine older adults with early memory changes. At 12 weeks, improved paired associate learning (p = 0.009) and word list recall (p = 0.04) were observed. In addition, there were trends suggesting reduced depressive symptoms (p = 0.08) and lower glucose levels (p = 0.10). We also compared the memory performances of the blueberry subjects with a demographically matched sample who consumed a berry placebo beverage in a companion trial of identical design and observed comparable results for paired associate learning. The findings of this preliminary study suggest that moderate-term blueberry supplementation can confer neurocognitive benefits.
The cognitive effects of acute blueberry anthocyanin interventions on 7–9 year old children (Whyte and Williams, 2012)
Anthocyanins, a group of flavonoids which are found in high concentrations in various foods and drinks such as blueberries, are postulated to promote healthy brain function. Indeed we have previously shown beneficial effects of blueberry anthocyanin treatment in adults on a variety of memory, attention and executive function tasks. Similar effects in a school-aged population, it could be argued, may enhance learning. Initial pilot work from our laboratory has shown improvements in memory using a sample of 8–9 year old children supplemented with a blueberry milkshake. In this experiment we describe a comprehensive time-course and dose-response analysis of these effects. Using a cross-over design, children (n = 21; 7–9 year olds) consumed a control, 126.5 mg or 253 mg blueberry anthocyanin drink performing a cognitive task battery at baseline, 1.5, 3 and 6 h following intervention. On an Auditory Verbal Learning Task, in comparison to control, both 126.5 mg and 253 mg anthocyanin treatments produced significantly better performance in delayed word recognition sustained over each test period post-supplementation. While on a flanker task, 253 mg anthocyanin treatment produced improved accuracy on incongruent trials, an effect that was particularly evident at 3 h post-supplementation. Taken together, these results support our previous findings showing beneficial effects of flavonoids on memory, whilst showing for the first time, improvements in attentional processing. Work is continuing to further investigate these effects.
Dietary intakes of berries and flavonoids in relation to cognitive decline (Devore et al, 2012)
Berries are high in flavonoids, especially anthocyanidins, and improve cognition in experimental studies. We prospectively evaluated whether greater long-term intakes of berries and flavonoids are associated with slower rates of cognitive decline in older women. Beginning in 1980, a semiquantitative food frequency questionnaire was administered every 4 years to Nurses' Health Study participants. In 1995–2001, we began measuring cognitive function in 16,010 participants, aged ≥70 years; follow-up assessments were conducted twice, at 2-year intervals. To ascertain long-term diet, we averaged dietary variables from 1980 through the initial cognitive interview. Using multivariate-adjusted, mixed linear regression, we estimated mean differences in slopes of cognitive decline by long-term berry and flavonoid intakes. Greater intakes of blueberries and strawberries were associated with slower rates of cognitive decline (eg, for a global score averaging all 6 cognitive tests, for blueberries: p-trend = 0.014 and mean difference = 0.04, 95% confidence interval [CI] = 0.01–0.07, comparing extreme categories of intake; for strawberries: p-trend = 0.022 and mean difference = 0.03, 95% CI = 0.00–0.06, comparing extreme categories of intake), after adjusting for multiple potential confounders. These effect estimates were equivalent to those we found for approximately 1.5 to 2.5 years of age in our cohort, indicating that berry intake appears to delay cognitive aging by up to 2.5 years. Additionally, in further supporting evidence, greater intakes of anthocyanidins and total flavonoids were associated with slower rates of cognitive decline (p-trends = 0.015 and 0.053, respectively, for the global score). Higher intake of flavonoids, particularly from berries, appears to reduce rates of cognitive decline in older adults.
Supporting Animal Studies
Effect of a polyphenol-rich wild blueberry extract on cognitive performance of mice, brain antioxidant markers and acetylcholinesterase activity (Papandreou et al, 2009)
The aim of this study was to examine the effect of a polyphenol-rich extract (PrB) of Vaccinium angustifolium(wild blueberries) introduced intraperitonealy (i.p.) at 30 (PrB30) and 60 (PrB60) mg/kg body weight for 7 days, on cognitive performance, brain oxidative status and acetylcholinesterase activity in adult, male, 3–4-month-old Balb-c mice. Results showed that the PrB60-treated mice exhibited a significant improvement in learning and memory (step-through latency time of 228 ± 38 s compared to 101 ± 32 s of the control group). PrB extract administration also resulted in reduced lipid peroxidation products (38 and 79%) and higher brain ascorbic acid levels (21 and 64%) in both PrB30 and PrB60-treated groups, respectively, and higher glutathione levels (28%) in the PrB60-treated group. Furthermore, salt- and detergent soluble AChE activity significantly decreased in both PrB-treated groups. Thus, the significant cognitive enhancement observed in adult mice after short-term i.p. supplementation with the blueberry extract concentrated in polyphenols, is closely related to higher brain antioxidant properties and inhibition of AChE activity.
Modulation of Hippocampal Plasticity and Cognitive Behavior by Short-term Blueberry Supplementation in Aged Rats (Cassadesus et al, 2004)
In this study, to begin to understand the mechanisms responsible for the beneficial effects of blueberries, we assessed changes in hippocampal plasticity parameters such as hippocampal neurogenesis, extracellular receptor kinase activation, and IGF-1 and IGF-1R levels in blueberry-supplemented aged animals. Our results show that all these parameters of hippocampal neuronal plasticity are increased in supplemented animals and aspects such as proliferation, extracellular receptor kinase activation and IGF-1 and IGF-1R levels correlate with improvements in spatial memory. Therefore, cognitive improvements afforded by polyphenolic-rich fruits such as blueberries appear, in part, to be mediated by their effects on hippocampal plasticity.
Reversals of Age-Related Declines in Neuronal Signal Transduction, Cognitive, and Motor Behavioral Deficits with Blueberry, Spinach, or Strawberry Dietary Supplementation (Joseph et al, 1999)
The present study showed that such supplements (strawberry, spinach, or blueberry at 14.8, 9.1, or 18.6 gm of dried aqueous extract per kilogram of diet, respectively) fed for 8 weeks to 19-month-old Fischer 344 rats were also effective in reversing age-related deficits in several neuronal and behavioral parameters including: oxotremorine enhancement of K+-evoked release of dopamine from striatal slices, carbachol-stimulated GTPase activity, striatal Ca45buffering in striatal synaptosomes, motor behavioral performance on the rod walking and accelerod tasks, and Morris water maze performance. These findings suggest that phytochemicals present in antioxidant-rich foods may be beneficial in reversing the course of neuronal and behavioral aging.
Blueberry-induced changes in spatial working memory correlate with changes in hippocampal CREB phosphorylation and brain-derived neurotrophic factor (BDNF) levels (Williams et al, 2008)
Phytochemical-rich foods have been shown to be effective at reversing age-related deficits in memory in both animals and humans. We show that a supplementation with a blueberry diet (2% w/w) for 12 weeks improves the performance of aged animals in spatial working memory tasks. This improvement emerged within 3 weeks and persisted for the remainder of the testing period. Memory performance correlated well with the activation of cAMP-response element-binding protein (CREB) and increases in both pro- and mature levels of brain-derived neurotrophic factor (BDNF) in the hippocampus. Changes in CREB and BDNF in aged and blueberry-supplemented animals were accompanied by increases in the phosphorylation state of extracellular signal-related kinase (ERK1/2), rather than that of calcium calmodulin kinase (CaMKII and CaMKIV) or protein kinase A. Furthermore, age and blueberry supplementation were linked to changes in the activation state of Akt, mTOR, and the levels of Arc/Arg3.1 in the hippocampus, suggesting that pathways involved in de novo protein synthesis may be involved. Although causal relationships cannot be made among supplementation, behavior, and biochemical parameters, the measurement of anthocyanins and flavanols in the brain following blueberry supplementation may indicate that changes in spatial working memory in aged animals are linked to the effects of flavonoids on the ERK-CREB-BDNF pathway.
Blueberry supplementation induces spatial memory improvements and region-specific regulation of hippocampal BDNF mRNA expression in young rats (Rendeiro et al, 2012)
Flavonoid-rich foods have been shown to be able to reverse age-related cognitive deficits in memory and learning in both animals and humans. However, to date, there have been only a limited number of studies investigating the effects of flavonoid-rich foods on cognition in young/healthy animals. The aim of this study was to investigate the effects of a blueberry-rich diet in young animals using a spatial working memory paradigm, the delayed non-match task, using an eight-arm radial maze. Furthermore, the mechanisms underlying such behavioural effects were investigated. We show that a 7-week supplementation with a blueberry diet (2 % w/w) improves the spatial memory performance of young rats (2 months old). Blueberry-fed animals also exhibited a faster rate of learning compared to those on the control diet. These behavioural outputs were accompanied by the activation of extracellular signal-related kinase (ERK1/2), increases in total cAMP-response element-binding protein (CREB) and elevated levels of pro- and mature brain-derived neurotrophic factor (BDNF) in the hippocampus. Changes in hippocampal CREB correlated well with memory performance. Further regional analysis of BDNF gene expression in the hippocampus revealed a specific increase in BDNF mRNA in the dentate gyrus and CA1 areas of hippocampi of blueberry-fed animals. The present study suggests that consumption of flavonoid-rich blueberries has a positive impact on spatial learning performance in young healthy animals, and these improvements are linked to the activation of ERK-CREB-BDNF pathway in the hippocampus.
Blueberry-enriched diet ameliorates age-related declines in NMDA receptor-dependent LTP (Coultrap et al, 2008)
NMDA receptor-dependent long-term potentiation (LTP) in the hippocampus is widely accepted as a cellular substrate for memory formation. Age-related declines in the expression of both NMDAR-dependent LTP and NMDAR subunit proteins in the CA1 region of the hippocampus have been well characterized and likely underlie age-related memory impairment. In the current study, we examined NMDAR-dependent LTP in young Fischer 344 rats (4 months old) and aged rats (24 months old) given either a control diet or a diet supplemented with blueberry extract for 6–8 weeks. NMDAR-dependent LTP was evoked by high-frequency stimulation (HFS) in the presence of nifedipine, to eliminate voltage-gated calcium channel LTP. Field excitatory postsynaptic potentials (fEPSPs) were increased by 57% 1 h after HFS in young animals, but this potentiation was reduced to 31% in aged animals. Supplementation of the diet with blueberry extract elevated LTP (63%) in aged animals to levels seen in young. The normalization of LTP may be due to the blueberry diet preventing a decline in synaptic strength, as measured by the slope of the fEPSP for a given fiber potential. The blueberry diet did not prevent age-related declines in NMDAR protein expression. However, phosphorylation of a key tyrosine residue on the NR2B subunit, important for increasing NMDAR function, was enhanced by the diet, suggesting that an increase in NMDAR function might overcome the loss in protein. This report provides evidence that dietary alterations later in life may prevent or postpone the cognitive declines associated with aging.
Behavioral and genoprotective effects of Vaccinium berries intake in mice (Barros et al, 2006)
Studies have shown that supplementation with berries rich in anthocyanins are effective in reducing oxidative stress associated with aging, and are beneficial in reversing age-related neuronal and behavioral changes. However, there are few reports on other biological activities of these polyphenols, such as genoprotective effects. The present experiments were performed to study the possible effects of 30-day administration of a lyophilized extract of Vaccinium ashei berries on cognitive performance using step-down inhibitory avoidance, open-field habituation and elevated plus-maze tasks, as well as on DNA damage in the hippocampus and cerebral cortex. The present study showed that the extract significantly enhanced long-term memory in the inhibitory avoidance task, induced an increase in the number of crossings during open-field habituation and had an anxiolytic effect in the elevated plus-maze task. Moreover, the extract reduced oxidative DNA damage in brain tissue in vitro. These results suggest that supplementation with V. asheiberries to mice improves performance on memory tasks and has a protective effect on DNA damage, possibly due to the antioxidant activity of polyphenols, including anthocyanins.
Dietary levels of pure flavonoids improve spatial memory performance and increase hippocampal brain-derived neurotrophic factor (Rendeiro et al, 2013)
Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods.
Contradictory Studies
None
Combinational Studies
None
Blueberry Supplementation Improves Memory in Older Adults (Krikorian et al, 2010)
This study investigated the effects of daily consumption of wild blueberry juice in a sample of nine older adults with early memory changes. At 12 weeks, improved paired associate learning (p = 0.009) and word list recall (p = 0.04) were observed. In addition, there were trends suggesting reduced depressive symptoms (p = 0.08) and lower glucose levels (p = 0.10). We also compared the memory performances of the blueberry subjects with a demographically matched sample who consumed a berry placebo beverage in a companion trial of identical design and observed comparable results for paired associate learning. The findings of this preliminary study suggest that moderate-term blueberry supplementation can confer neurocognitive benefits.
The cognitive effects of acute blueberry anthocyanin interventions on 7–9 year old children (Whyte and Williams, 2012)
Anthocyanins, a group of flavonoids which are found in high concentrations in various foods and drinks such as blueberries, are postulated to promote healthy brain function. Indeed we have previously shown beneficial effects of blueberry anthocyanin treatment in adults on a variety of memory, attention and executive function tasks. Similar effects in a school-aged population, it could be argued, may enhance learning. Initial pilot work from our laboratory has shown improvements in memory using a sample of 8–9 year old children supplemented with a blueberry milkshake. In this experiment we describe a comprehensive time-course and dose-response analysis of these effects. Using a cross-over design, children (n = 21; 7–9 year olds) consumed a control, 126.5 mg or 253 mg blueberry anthocyanin drink performing a cognitive task battery at baseline, 1.5, 3 and 6 h following intervention. On an Auditory Verbal Learning Task, in comparison to control, both 126.5 mg and 253 mg anthocyanin treatments produced significantly better performance in delayed word recognition sustained over each test period post-supplementation. While on a flanker task, 253 mg anthocyanin treatment produced improved accuracy on incongruent trials, an effect that was particularly evident at 3 h post-supplementation. Taken together, these results support our previous findings showing beneficial effects of flavonoids on memory, whilst showing for the first time, improvements in attentional processing. Work is continuing to further investigate these effects.
Dietary intakes of berries and flavonoids in relation to cognitive decline (Devore et al, 2012)
Berries are high in flavonoids, especially anthocyanidins, and improve cognition in experimental studies. We prospectively evaluated whether greater long-term intakes of berries and flavonoids are associated with slower rates of cognitive decline in older women. Beginning in 1980, a semiquantitative food frequency questionnaire was administered every 4 years to Nurses' Health Study participants. In 1995–2001, we began measuring cognitive function in 16,010 participants, aged ≥70 years; follow-up assessments were conducted twice, at 2-year intervals. To ascertain long-term diet, we averaged dietary variables from 1980 through the initial cognitive interview. Using multivariate-adjusted, mixed linear regression, we estimated mean differences in slopes of cognitive decline by long-term berry and flavonoid intakes. Greater intakes of blueberries and strawberries were associated with slower rates of cognitive decline (eg, for a global score averaging all 6 cognitive tests, for blueberries: p-trend = 0.014 and mean difference = 0.04, 95% confidence interval [CI] = 0.01–0.07, comparing extreme categories of intake; for strawberries: p-trend = 0.022 and mean difference = 0.03, 95% CI = 0.00–0.06, comparing extreme categories of intake), after adjusting for multiple potential confounders. These effect estimates were equivalent to those we found for approximately 1.5 to 2.5 years of age in our cohort, indicating that berry intake appears to delay cognitive aging by up to 2.5 years. Additionally, in further supporting evidence, greater intakes of anthocyanidins and total flavonoids were associated with slower rates of cognitive decline (p-trends = 0.015 and 0.053, respectively, for the global score). Higher intake of flavonoids, particularly from berries, appears to reduce rates of cognitive decline in older adults.
Supporting Animal Studies
Effect of a polyphenol-rich wild blueberry extract on cognitive performance of mice, brain antioxidant markers and acetylcholinesterase activity (Papandreou et al, 2009)
The aim of this study was to examine the effect of a polyphenol-rich extract (PrB) of Vaccinium angustifolium(wild blueberries) introduced intraperitonealy (i.p.) at 30 (PrB30) and 60 (PrB60) mg/kg body weight for 7 days, on cognitive performance, brain oxidative status and acetylcholinesterase activity in adult, male, 3–4-month-old Balb-c mice. Results showed that the PrB60-treated mice exhibited a significant improvement in learning and memory (step-through latency time of 228 ± 38 s compared to 101 ± 32 s of the control group). PrB extract administration also resulted in reduced lipid peroxidation products (38 and 79%) and higher brain ascorbic acid levels (21 and 64%) in both PrB30 and PrB60-treated groups, respectively, and higher glutathione levels (28%) in the PrB60-treated group. Furthermore, salt- and detergent soluble AChE activity significantly decreased in both PrB-treated groups. Thus, the significant cognitive enhancement observed in adult mice after short-term i.p. supplementation with the blueberry extract concentrated in polyphenols, is closely related to higher brain antioxidant properties and inhibition of AChE activity.
Modulation of Hippocampal Plasticity and Cognitive Behavior by Short-term Blueberry Supplementation in Aged Rats (Cassadesus et al, 2004)
In this study, to begin to understand the mechanisms responsible for the beneficial effects of blueberries, we assessed changes in hippocampal plasticity parameters such as hippocampal neurogenesis, extracellular receptor kinase activation, and IGF-1 and IGF-1R levels in blueberry-supplemented aged animals. Our results show that all these parameters of hippocampal neuronal plasticity are increased in supplemented animals and aspects such as proliferation, extracellular receptor kinase activation and IGF-1 and IGF-1R levels correlate with improvements in spatial memory. Therefore, cognitive improvements afforded by polyphenolic-rich fruits such as blueberries appear, in part, to be mediated by their effects on hippocampal plasticity.
Reversals of Age-Related Declines in Neuronal Signal Transduction, Cognitive, and Motor Behavioral Deficits with Blueberry, Spinach, or Strawberry Dietary Supplementation (Joseph et al, 1999)
The present study showed that such supplements (strawberry, spinach, or blueberry at 14.8, 9.1, or 18.6 gm of dried aqueous extract per kilogram of diet, respectively) fed for 8 weeks to 19-month-old Fischer 344 rats were also effective in reversing age-related deficits in several neuronal and behavioral parameters including: oxotremorine enhancement of K+-evoked release of dopamine from striatal slices, carbachol-stimulated GTPase activity, striatal Ca45buffering in striatal synaptosomes, motor behavioral performance on the rod walking and accelerod tasks, and Morris water maze performance. These findings suggest that phytochemicals present in antioxidant-rich foods may be beneficial in reversing the course of neuronal and behavioral aging.
Blueberry-induced changes in spatial working memory correlate with changes in hippocampal CREB phosphorylation and brain-derived neurotrophic factor (BDNF) levels (Williams et al, 2008)
Phytochemical-rich foods have been shown to be effective at reversing age-related deficits in memory in both animals and humans. We show that a supplementation with a blueberry diet (2% w/w) for 12 weeks improves the performance of aged animals in spatial working memory tasks. This improvement emerged within 3 weeks and persisted for the remainder of the testing period. Memory performance correlated well with the activation of cAMP-response element-binding protein (CREB) and increases in both pro- and mature levels of brain-derived neurotrophic factor (BDNF) in the hippocampus. Changes in CREB and BDNF in aged and blueberry-supplemented animals were accompanied by increases in the phosphorylation state of extracellular signal-related kinase (ERK1/2), rather than that of calcium calmodulin kinase (CaMKII and CaMKIV) or protein kinase A. Furthermore, age and blueberry supplementation were linked to changes in the activation state of Akt, mTOR, and the levels of Arc/Arg3.1 in the hippocampus, suggesting that pathways involved in de novo protein synthesis may be involved. Although causal relationships cannot be made among supplementation, behavior, and biochemical parameters, the measurement of anthocyanins and flavanols in the brain following blueberry supplementation may indicate that changes in spatial working memory in aged animals are linked to the effects of flavonoids on the ERK-CREB-BDNF pathway.
Blueberry supplementation induces spatial memory improvements and region-specific regulation of hippocampal BDNF mRNA expression in young rats (Rendeiro et al, 2012)
Flavonoid-rich foods have been shown to be able to reverse age-related cognitive deficits in memory and learning in both animals and humans. However, to date, there have been only a limited number of studies investigating the effects of flavonoid-rich foods on cognition in young/healthy animals. The aim of this study was to investigate the effects of a blueberry-rich diet in young animals using a spatial working memory paradigm, the delayed non-match task, using an eight-arm radial maze. Furthermore, the mechanisms underlying such behavioural effects were investigated. We show that a 7-week supplementation with a blueberry diet (2 % w/w) improves the spatial memory performance of young rats (2 months old). Blueberry-fed animals also exhibited a faster rate of learning compared to those on the control diet. These behavioural outputs were accompanied by the activation of extracellular signal-related kinase (ERK1/2), increases in total cAMP-response element-binding protein (CREB) and elevated levels of pro- and mature brain-derived neurotrophic factor (BDNF) in the hippocampus. Changes in hippocampal CREB correlated well with memory performance. Further regional analysis of BDNF gene expression in the hippocampus revealed a specific increase in BDNF mRNA in the dentate gyrus and CA1 areas of hippocampi of blueberry-fed animals. The present study suggests that consumption of flavonoid-rich blueberries has a positive impact on spatial learning performance in young healthy animals, and these improvements are linked to the activation of ERK-CREB-BDNF pathway in the hippocampus.
Blueberry-enriched diet ameliorates age-related declines in NMDA receptor-dependent LTP (Coultrap et al, 2008)
NMDA receptor-dependent long-term potentiation (LTP) in the hippocampus is widely accepted as a cellular substrate for memory formation. Age-related declines in the expression of both NMDAR-dependent LTP and NMDAR subunit proteins in the CA1 region of the hippocampus have been well characterized and likely underlie age-related memory impairment. In the current study, we examined NMDAR-dependent LTP in young Fischer 344 rats (4 months old) and aged rats (24 months old) given either a control diet or a diet supplemented with blueberry extract for 6–8 weeks. NMDAR-dependent LTP was evoked by high-frequency stimulation (HFS) in the presence of nifedipine, to eliminate voltage-gated calcium channel LTP. Field excitatory postsynaptic potentials (fEPSPs) were increased by 57% 1 h after HFS in young animals, but this potentiation was reduced to 31% in aged animals. Supplementation of the diet with blueberry extract elevated LTP (63%) in aged animals to levels seen in young. The normalization of LTP may be due to the blueberry diet preventing a decline in synaptic strength, as measured by the slope of the fEPSP for a given fiber potential. The blueberry diet did not prevent age-related declines in NMDAR protein expression. However, phosphorylation of a key tyrosine residue on the NR2B subunit, important for increasing NMDAR function, was enhanced by the diet, suggesting that an increase in NMDAR function might overcome the loss in protein. This report provides evidence that dietary alterations later in life may prevent or postpone the cognitive declines associated with aging.
Behavioral and genoprotective effects of Vaccinium berries intake in mice (Barros et al, 2006)
Studies have shown that supplementation with berries rich in anthocyanins are effective in reducing oxidative stress associated with aging, and are beneficial in reversing age-related neuronal and behavioral changes. However, there are few reports on other biological activities of these polyphenols, such as genoprotective effects. The present experiments were performed to study the possible effects of 30-day administration of a lyophilized extract of Vaccinium ashei berries on cognitive performance using step-down inhibitory avoidance, open-field habituation and elevated plus-maze tasks, as well as on DNA damage in the hippocampus and cerebral cortex. The present study showed that the extract significantly enhanced long-term memory in the inhibitory avoidance task, induced an increase in the number of crossings during open-field habituation and had an anxiolytic effect in the elevated plus-maze task. Moreover, the extract reduced oxidative DNA damage in brain tissue in vitro. These results suggest that supplementation with V. asheiberries to mice improves performance on memory tasks and has a protective effect on DNA damage, possibly due to the antioxidant activity of polyphenols, including anthocyanins.
Dietary levels of pure flavonoids improve spatial memory performance and increase hippocampal brain-derived neurotrophic factor (Rendeiro et al, 2013)
Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods.
Contradictory Studies
None
Combinational Studies
None