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Green Tea Consumption Affects Cognitive Dysfunction in the Elderly: A Pilot Study


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Green tea is known to have various health benefits for humans. However, the effect of green tea consumption on cognitive dysfunction remains to be clinically verified. We conducted a clinical study to investigate the effects of green tea consumption on cognitive dysfunction. Twelve elderly nursing home residents with cognitive dysfunction (Mini-Mental State Examination Japanese version (MMSE-J) score: <28) participated in the study (2 men, 10 women; mean age, 88 years). The participants consumed green tea powder 2 g/day for 3 months. After three months of green tea consumption, the participants' MMSE-J scores were significantly improved (before, 15.3 ± 7.7; after, 17.0 ± 8.2; p = 0.03). This result suggests that green tea consumption may be effective in improving cognitive function or reducing the progression of cognitive dysfunction; however, long-term large-scale controlled studies are needed to further clarify the effect.
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Nutrients 2014, 6, 4032-4042; doi:10.3390/nu6104032
ISSN 2072-6643
Green Tea Consumption Affects Cognitive Dysfunction in the
Elderly: A Pilot Study
Kazuki Ide 1, Hiroshi Yamada 1,*, Norikata Takuma 2, Mijong Park 1, Noriko Wakamiya 1,
Junpei Nakase 3, Yuuichi Ukawa 3 and Yuko M. Sagesaka 3
1 Department of Drug Evaluation and Informatics, Graduate School of Pharmaceutical Sciences,
University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan;
E-Mails: (K.I.); (M.P.);
m08129@ (N.W.)
2 White Cross Nursing Home, 2-26-1 Suwa-cho, Higashimurayama, Tokyo 189-0021, Japan;
3 Central Research Institute, ITO EN, Ltd., 21 Mekami, Makinohara, Shizuoka 421-0516, Japan;
E-Mails: (J.N.); (Y.U.); (Y.M.S.)
* Author to whom correspondence should be addressed; E-Mail:;
Tel./Fax: +81-264-5762.
Received: 10 May 2014; in revised form: 14 July 2014 / Accepted: 19 September 2014 /
Published: 29 September 2014
Abstract: Green tea is known to have various health benefits for humans. However, the
effect of green tea consumption on cognitive dysfunction remains to be clinically verified.
We conducted a clinical study to investigate the effects of green tea consumption on
cognitive dysfunction. Twelve elderly nursing home residents with cognitive dysfunction
(Mini-Mental State Examination Japanese version (MMSE-J) score: <28) participated in the
study (2 men, 10 women; mean age, 88 years). The participants consumed green tea powder
2 g/day for 3 months. After three months of green tea consumption, the participants’
MMSE-J scores were significantly improved (before, 15.3 ± 7.7; after, 17.0 ± 8.2; p = 0.03).
This result suggests that green tea consumption may be effective in improving cognitive
function or reducing the progression of cognitive dysfunction; however, long-term
large-scale controlled studies are needed to further clarify the effect.
Keywords: green tea; oral administration; cognitive function; elderly
Nutrients 2014, 6 4033
1. Introduction
In rapidly aging societies around the world, the number of patients with cognitive dysfunction,
particularly dementia, is gradually increasing [1]. Dementia affects 5.4% of people over 65 years
of age worldwide, and its prevalence increases with age [2]. There are several pharmaceutical and
non-pharmaceutical treatments for dementia; however, thus far, no fundamental curative therapy has
been established [3,4].
Green tea, one of the commonly consumed beverages in Asian countries, is known to have various
health benefits [5–7]. A number of experimental studies in vitro and in vivo have shown the
neuroprotective effects of green tea and its components, such as catechins and theanine [8–11].
Anti-oxidative and anti-inflammatory effects of these components have been reported [10–12], and such
effects may contribute to neuroprotection. Regarding cognitive function, catechins have been reported
to improve performance on cognition tests in rodent models of dementia, such as the Morris water maze,
probe test, and passive avoidance test [10]. In mice, theanine has also been shown to attenuate memory
impairment induced by amyloid protein, an Alzheimer’s disease trigger protein [9].
Furthermore, several human epidemiological studies have shown a relationship between tea
consumption and cognitive function [13–18]. One study showed a negative association between
green tea consumption and the prevalence of cognitive impairment in elderly individuals over 70 years
old [13]. Similar negative association has also been reported in other observational studies on tea
consumption [14–16,18]. These studies suggest that tea consumption effects cognitive function; however,
only limited interventional studies have been reported, and these effects remain to be clinically
verified [19,20]. One interventional study used a supplement called LGNC-07 containing 1440 mg green
tea extract and 240 mg theanine as a daily dose [19]. It should be noted that LGNC-07 is a green-tea-
based supplement, not green tea as it is typically drunk, thus, it is important to also study the effect of
ordinary daily green tea consumption patterns on cognitive function.
In addition to the effect of green tea consumption on cognitive function, several studies have shown
that it also reduces the risk of developing hypertension [21] and lowers both total cholesterol (TC)
concentration and low density lipoprotein cholesterol (LDL-C) concentration in adults [22]. Clinical
significance of these effects is still inconclusive; however, hypertension and dyslipidemia are risk factors
for atherosclerosis [23,24], and atherosclerosis is in turn related to cognitive dysfunction. Therefore,
green tea consumption may also reduce the progression of cognitive dysfunction indirectly by reducing
the effect of these related health problems on atherosclerosis.
Based on this previous research, we conducted a clinical study to investigate the effects of green tea
consumption on cognitive dysfunction and atherosclerotic risk factors in the elderly.
Nutrients 2014, 6 4034
2. Experimental Section
2.1. Subjects
This study was conducted from July to September 2012 at the White Cross Nursing Home in Higashi-
Murayama, Japan. Recruitment was performed at the nursing home by posters. Fifteen elderly residents
with cognitive impairment were enrolled. Inclusion criteria were as follows: (1) >65 years of age; (2)
ability to orally ingest green tea powder; (3) no consumption of supplements with antioxidant effects
(vitamins E, C, and A, and β-carotene) during the study period; and (4) a Mini-Mental State Examination-
Japanese version (MMSE-J) score of <28 [25]. Exclusion criteria were: (1) tea allergy; (2) severe cardiac,
respiratory, hepatic, or renal dysfunction; and (3) severe anemia. The diagnoses of the patients were
simply taken from the medical records at White Cross Hospital in Higashi-Murayama, Japan.
Written informed consent was obtained from both the subjects and their caregivers prior to enrollment.
The study protocol was approved by the Ethics Committee of the University of Shizuoka (No. 23-27,
approved on 11 May, 2012) and conducted in accordance with the Declaration of Helsinki. This pilot
study was registered with Clinical (NCT 01594086).
2.2. Study Design
The following baseline characteristics of subjects were recorded: age, sex, underlying diseases,
complications, medication, alcohol consumption, smoking habits, tea or supplement consumption habits,
activity of daily living, and brain magnetic resonance imaging (MRI) or computed tomography
(CT) findings.
The subjects were asked to consume green tea powder (2 g/day, containing 227 mg catechins and
42 mg theanine, manufactured by ITO EN Ltd. (Tokyo, Japan)) during meals for a period of 3 months.
The consumption of other supplements that could have antioxidant effects was prohibited during the
intervention period and for a seven-day washout period prior to the start of the intervention. Subjects
were advised to maintain their customary intake of home-brewed green tea or tea beverages during the
study period. The caregiving staff at the nursing home kept a diary for each subject in which they
recorded the daily intake of green tea powder, the amount of home-brewed green tea or tea beverages
consumed each day, any changes in the health of subjects or in the administration of medication, and the
occurrence of any adverse events.
MMSE-J tests were performed to assess the cognitive function of subjects. In addition, the following
data was collected: blood pressure; serum lipid levels, including TC, LDL-C, HDL-C, and triglycerides;
and blood glucose levels. All tests were performed at baseline and again after three months of green
tea consumption.
2.3. Statistical Analysis
Changes in MMSE-J scores, including scores for specific cognitive domains, as well as clinical and
laboratory values obtained at baseline and three months after the start of green tea consumption were
determined by paired t-test or Wilcoxon signed-rank test. Statistical significance was set at p < 0.05. All
Nutrients 2014, 6 4035
statistical procedures were performed with IBM SPSS version 20.0 for Windows (IBM Corp., Armonk,
NY, US).
3. Results
A total of 15 nursing home elderly residents and their caregivers gave written informed consent, and
were assessed for eligibility. One resident was excluded according to the exclusion criteria. Two
residents were excluded from the study after it had begun due to the retracting of their consent, so it was
not possible to obtain intervention data for these individuals. A total of 12 subjects (2 men,
10 women) completed the study. During the study period, a subject was hospitalized due to a hip fracture
but resumed participation 36 days after the initial enrollment. The mean age of subjects was
88 ± 7.6 (range, 70–98) years; eight subjects had vascular dementia, three had Alzheimer’s disease and
one had dementia with Lewy body. The characteristics of subjects are reported in Table 1. The
MMSE-J score distribution of the subjects prior to the intervention was as follows: 24–27 (mild cognitive
impairment (MCI)), two subjects (16.7%); 10–23 (mild and moderate dementia), six subjects (50.0%);
and 0–9 (severe dementia), four subjects (33.3%). Adherence to the green tea powder consumption
protocol was 99.7%.
Table 1. Clinical characteristics of study subjects.
Clinical Characteristic
Number of subjects 12
Age, mean ± SD (range) 88 ± 7.6 (70–98)
Sex, n (%)
Men 2 (16.7)
Women 10 (83.3)
Underlying disease, n (%)
Alzheimer’s disease 3 (25.0)
Vascular dementia 8 (66.7)
Dementia with Lewy bodies 1 (8.3)
MMSE-J score, n (%)
24–27 (MCI) 2 (16.7)
10–23 (mild to moderate) 6 (50.0)
0–9 (severe) 4 (33.3)
Complication a, n (%)
Hypertension 8 (66.7)
Diabetes 2 (16.7)
Hyperuricemia 1 (8.3)
Concomitant drug a, n (%)
Antihypertensive drug 8 (66.7)
Drug for hyperuricemia 2 (16.7)
Antidiabetic drug 1 (8.3)
Drug for dementia 1 (8.3)
Activities of daily living
Independence 0 (0.0)
Some assistance is necessary 12 (100)
Nutrients 2014, 6 4036
Table 1. Cont.
Clinical Characteristic
Usual tea consumption
Green tea, n (%) 12 (100)
Mean ± SD, mL/day 680 ± 229.8
Others b, n (%) 8 (66.7)
Mean ± SD, mL/day 85 ± 63.7
Alcohol use, n (%) 0 (0.0)
Smoking, n (%) 2 (16.7)
Dietary supplements, n (%) 0 (0.0)
MMSE-J, Mini-Mental State Examination Japanese version; MCI, Mild cognitive impairment. a More than one
choice was possible, b black tea or oolong tea.
Changes in MMSE-J scores before and after the intervention are shown in Table 2. Total MMSE-J
scores (mean ± SD) taken at baseline were significantly improved after three months of green tea
consumption (before, 15.3 ± 7.7; after, 17.0 ± 8.2; p = 0.03). In terms of specific cognitive domains, the
baseline scores for short-term memory (registration and recall) were significantly improved after the
intervention (before, 2.0 ± 1.8; after, 3.2 ± 1.8; p = 0.01) (Table 2).
In post hoc analysis for vascular dementia (n = 8), the MMSE-J scores (mean ± SD) were significantly
improved after the intervention (before, 18.4 ± 6.5; after, 20.6 ± 6.7; p = 0.03), and short-term memory
were also improved significantly (before, 2.6 ± 1.6; after, 4.0 ± 1.2; p = 0.04) (Table 2).
Table 2. MMSE-J scores before and after 3 months of green tea consumption.
Cognitive Function (MMSE-J Score) Green Tea Consumption (2 g/day)
Before After p Value
All subjects (n = 12)
Total MMSE-J score (max, 30) 15.3 ± 7.7 17.0 ± 8.2 0.03 t
Orientation (max, 10) 4.2 ± 3.1 4.3 ± 3.9 0.96 w
Short-term memory (max, 6) 2.0 ± 1.8 3.2 ± 1.8 0.01 t
Attention and calculation (max, 5) 2.1 ± 2.0 2.0 ± 2.3 0.91 w
Language (max, 8) 6.7 ± 1.7 6.9 ± 1.4 0.46 w
Visual construction (max, 1) 0.4 ± 0.5 0.7 ± 0.5 0.08 w
Vascular dementia (n = 8)
Total MMSE-J score (max, 30) 18.4 ± 6.5 20.6 ± 6.7 0.03 t
Orientation (max, 10) 5.1 ± 3.3 5.8 ± 3.8 0.11 t
Short-term memory (max, 6) 2.6 ± 1.6 4.0 ± 1.2 0.04 w
Attention and calculation (max, 5) 2.8 ± 1.9 2.5 ± 2.3 0.68 w
Language (max, 8) 7.4 ± 0.9 7.5 ± 0.9 0.32 w
Visual construction (max, 1) 0.5 ± 0.5 0.8 ± 0.5 0.16 w
Stratified analysis at each stages of cognitive dysfunction
Total MMSE-J score (max 30)
MCI (n = 2) 26.5 ± 0.7 29.0 ± 1.4 0.34 t
Mild to moderate (n = 6) 17.3 ± 3.7 18.8 ± 4.3 0.19 t
Severe (n = 4) 6.8 ± 1.7 8.3 ± 3.4 0.32 t
Values: Mean ± SD. Each p value was calculated using the following statistical method: t paired t-test, w Wilcoxon
signed-rank test. MMSE-J, Mini-Mental State Examination Japanese version; MCI, Mild cognitive impairment.
Nutrients 2014, 6 4037
After three months of green tea consumption, the triglyceride (TG) levels of subjects were
significantly lower than those measured at baseline (124 ± 80 mg/dL vs 103 ± 57 mg/dL; p = 0.04).
However, blood pressure, lipid profiles (TC, LDL-C, and high density lipoprotein cholesterol (HDL-C)),
and blood glucose levels were not significantly different (Table 3).
No serious adverse events associated with green tea consumption were observed during the
study period.
Table 3. Values of atherosclerotic factors before and after 3 months of green tea consumption.
Atherosclerotic factor Green Tea Consumption (2 g/day)
Before After p Value
All subjects (n = 12)
Blood pressure
SBP (mmHg) 119 ± 19 126 ± 19 0.32 t
DBP (mmHg) 65 ± 13 70 ± 12 0.19 t
Serum lipid levels
TC (mg/dL) 190 ± 33 189 ± 28 0.84 t
HDL-C (mg/dL) 47 ± 18 48 ± 16 0.78 t
LDL-C (mg/dL) 112 ± 24 112 ± 27 0.97 t
TG (mg/dL) 124 ± 80 103 ± 57 0.04 w
Blood glucose levels
FPG (mg/dL) 124 ± 52 124 ± 38 0.86 w
HbA1c (%) 5.3 ± 0.6 5.2 ± 0.6 0.14 w
Values: Mean±SD. Each p value was calculated using the following statistical method: t paired t-test,
w Wilcoxon signed-rank test. SBP, Systolic blood pressure; DBP, Diastolic blood pressure; TC, total
cholesterol; HDL-C, high density lipoprotein cholesterol; LDL-C, low density lipoprotein cholesterol;
TG, Triglyceride; FPG, fasting plasma glucose; HbA1c: hemoglobin A1c.
4. Discussion
In this pilot study conducted to investigate the effect of green tea consumption on cognitive
dysfunction and atherosclerotic risk factors in the elderly, we found that three months of green tea
consumption improved cognitive dysfunction based on MMSE-J score changes. Among MMSE-J
domains, the short-term memory domain was especially improved. These results support the findings of
previous epidemiological studies, and additionally demonstrate that green tea improves cognitive
function or reduces the progression of cognitive dysfunction even at the relatively low catechin and
theanine concentrations that can be obtained from ordinary levels of daily green tea intake. The green
tea powder used as a daily dose in this study contained as its main bioactive components 227 mg of
catechins and 42 mg of theanine, concentrations that are approximately equal to two to four cups of
bottled or home-brewed green tea.
The effect on cognitive function estimated by MMSE-J in this study may be partially explained in
terms of basic studies on the bioactive components of green tea, such as catechins and theanine. The
anti-oxidative and anti-inflammatory properties of these components [10–12] may have contributed to
the effect of green tea consumption on cognitive function. In addition to these properties, recent findings
have suggested that green tea may exert its neuroprotective effect through a variety of different
Nutrients 2014, 6 4038
mechanisms, including: tea polyphenols inhibiting acetylcholinesterase, which is a target for
Alzheimer’s disease medications [26]; green tea extract regulating the secretion of stress hormones such
as corticosterone, which is related to cognitive function [27]; and L-theanine modulating serotoninergic
[28–30], dopaminergic [30], and GABAergic [31] neurotransmission in brain. In particular, research on
acetylcholinesterase inhibition has shown that tea polyphenols, including catechins and theanine, also
blunted scopolamine-induced learning and memory impairment in model mice [26]. In addition, other
ingredients, such as caffeine, might also be related to the improvement of MMSE-J scores by alerting
influence [32]. In human, neural modulation related to cognitive function by green tea consumption have
been largely uncertain. However, recently, an enhancement of parieto-frontal connectivity by green tea
consumption was reported [33]. Parieto-frontal connectivity contributes working memory processing;
therefore, it might be related in part to the effect of green tea on the improvement of MMSE-J score.
Post hoc analysis of vascular dementia data (n = 8) showed that total MMSE-J scores and short-term
memory domain scores were significantly improved after three months of green tea consumption.
Vascular dementia, the second most common type of dementia after Alzheimer’s disease, is
characterized by cognitive deficit of cerebrovascular origin. Our results indicate that green tea has
potential as a neuroprotective agent, especially for vascular dementia.
Individual MMSE-J scores tended to improve slightly regardless of the severity of cognitive
dysfunction; however, a significant difference was not observed in the stratified analysis at each stage
of cognitive dysfunction. One reason for this may be the small number of participants in this study.
There are several limitations in this study. Non-blinded, non-placebo controlled design is the main
limitation. First, the participants believed that they were taking a compound that might help them, and it
may induce a placebo effect on the MMSE-J scores. Second, the MMSE-J were administered twice at
the three-month interval. A test-retest effect on the examination could not be eliminated.
In addition, the participants of this study were regular green tea drinker. The nursing home care and
diet was not changed during study period, but baseline green tea drinking elevates the catechin
and theanine consumptions, and it might affect the changes of MMSE-J scores and atherosclerotic
risk factors.
Not measuring depression and other neuropsychiatric symptoms are also possible limitations.
Association between late life depression and dementia has been reported [33–36]; therefore, it is not
ruled out whether cognitive impairment is secondary to the improvement on mood. In future studies,
study designs should be improved; a blinded, placebo controlled design is adequate to evaluate the
efficacy of green tea consumption.
Our findings related to atherosclerotic risk factors showed that serum TG levels were significantly
lowered. This suggests that green tea may be protective against vascular atherosclerosis in the elderly.
The TG-lowering effect of green tea is also supported by the previously-reported meta-analysis by Zheng
et al. [22]. However, clinical significance of the TG-lowering effects and its relationship with cognitive
function were still inconclusive, and the other atherosclerotic risk factors assessed in this study, including
LDL-C and HDL-C, did not show a significant change. The fact that the inclusion and exclusion criteria
of this study were not focused on patients with atherosclerotic risk factors, and the short term intervention
of this study are limitations; future studies on patients with atherosclerotic risk factors with long study
period should more clearly reveal both the effect of green tea consumption on these risk factors and the
relationship between the risk factors and cognitive function.
Nutrients 2014, 6 4039
5. Conclusions
In conclusion, our results suggest that green tea consumption may be effective in improving cognitive
function or reducing the progression of cognitive dysfunction in elderly individuals, and that it may
similarly reduce the progression of vascular dementia. However, there are several limitations related to
the study design. Additional long-term large-scale randomized controlled studies are needed both to
establish evidence for the effect of green tea consumption on cognitive dysfunction, and to reveal the
relationship between this effect and atherosclerotic risk factors.
We gratefully acknowledge the individuals who participated in the study and the clinical research
coordinators. We thank the medical staff at White Cross Nursing Home (Sadako Fujii, Atsuko Nakahara,
and Tsuyoshi Suzuki) for their dedicated cooperation. We also thank Philip Hawke of the University of
Shizuoka Scientific English Program for his comments on the English in the manuscript.
Author Contributions
Kazuki Ide and Mijong Park wrote the main manuscript text, designed the study, and analyzed the
data. Hiroshi Yamada was the principal investigator as a clinical neurologist and involved in designing
the study. Norikata Takuma was a site investigator as a primary care physician and involved in designing
the study. Noriko Wakamiya supported the data management and data analysis. Junpei Nakase,
Yuuichi Ukawa and Yuko M. Sagesaka were involved in designing the study. All authors reviewed and
approved the contents of the manuscript.
Conflicts of Interest
Hiroshi Yamada was funded by a grant from the Japanese Ministry of Health, Labor and Welfare (No.
242-20-501), and a grant from ITO EN Ltd. (No. 12-311). Junpei Nakase, Yuuichi Ukawa,
Yuko M. Sagesaka are employees of ITO EN Ltd.; the company that provide the green tea powder used
in this study. Kazuki Ide, Norikata Takuma, Mijong Park, and Noriko Wakamiya declare no
competing interests.
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... The effects of green tea supplementation were evaluated in a nonblinded, non-placebo-controlled study design (NCT01594086). Although the study had a number of limitations, the authors described that three months of green tea consumption improved cognitive dysfunction in the elderly [227]. COSMOS-Mind was the first large-scale, long-term randomized controlled trial (NCT03035201) to assess the long-term effects of cocoa extract (containing 500 mg/day of cocoa flavanols) on global cognition in older women and men. ...
... The effects of green tea supplementation were evaluated in a nonblinded, non-placebocontrolled study design (NCT01594086). Although the study had a number of limitations, the authors described that three months of green tea consumption improved cognitive dysfunction in the elderly [227]. COSMOS-Mind was the first large-scale, long-term randomized controlled trial (NCT03035201) to assess the long-term effects of cocoa extract (containing 500 mg/day of cocoa flavanols) on global cognition in older women and men. ...
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Ageing is a complex process characterized mainly by a decline in the function of cells, tissues, and organs, resulting in an increased risk of mortality. This process involves several changes, described as hallmarks of ageing, which include genomic instability, telomere attrition, epigenetic changes, loss of proteostasis, dysregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell depletion, and altered intracellular communication. The determining role that environmental factors such as diet and lifestyle play on health, life expectancy, and susceptibility to diseases, including cancer and neurodegenerative diseases, is wellestablished. In view of the growing interest in the beneficial effects of phytochemicals in the prevention of chronic diseases, several studies have been conducted, and they strongly suggest that the intake of dietary polyphenols may bring numerous benefits due to their antioxidant and anti-inflammatory properties, and their intake has been associated with impaired ageing in humans. Polyphenol intake has been shown to be effective in ameliorating several age-related phenotypes, including oxidative stress, inflammatory processes, impaired proteostasis, and cellular senescence, among other features, which contribute to an increased risk of ageing-associated diseases. This review aims to address, in a general way, the main findings described in the literature about the benefits of polyphenols in each of the hallmarks of ageing, as well as the main regulatory mechanisms responsible for the observed antiageing effects.
... However, recent studies have also highlighted the potential therapeutic benefits of EGCG across a wide range of other disorders, including AD, PD, respiratory-, cardiovascular-, and metabolic diseases (e.g., diabetes mellitus and obesity). The neuroprotective properties of EGCG and its metabolites have been extensively studied, and there is a positive correlation between frequent tea consumption and enhanced cognitive function or the mitigation of cognitive impairment [193,194]. Intragastric administration of EGCG prevents cognitive deterioration in senescence-accelerated mice and decreases the accumulation of β-amyloid. EGCG, furthermore, attenuates β-amyloid-induced cognitive impairment by regulating secretase activity through ERK and NF-κB [195]. ...
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Neurodegenerative disorders (NDDs) are major health issues in Western countries. Despite significant efforts, no effective therapeutics for NDDs exist. Several drugs that target epigenetic mechanisms (epidrugs) have been recently developed for the treatment of NDDs, and several of these are currently being tested in clinical trials. Furthermore, various bioproducts have shown important biological effects for the potential prevention and treatment of these disorders. Here, we review the use of natural products as epidrugs to treat NDDs in order to explore the epigenetic effects and benefits of functional foods and natural bioproducts on neurodegeneration.
... The benefits of EGCG and its metabolites in neurological disorders have been recently described in several excellent reviews [226][227][228]. Epidemiological studies in Japan, China, and Singapore have demonstrated a positive relation between drinking tea and improved cognitive functions or prevention of cognitive dysfunction [229][230][231][232][233][234]. These findings were supported by the results from numerous animal studies [235]. ...
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(‒)-Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenol in green tea. Thanks to multiple interactions with cell surface receptors, intracellular signaling pathways, and nuclear transcription factors, EGCG possesses a wide variety of anti-inflammatory, antioxidant, antifibrotic, anti-remodelation, and tissue-protective properties which may be useful in the treatment of various diseases, particularly in cancer, and neurological, cardiovascular, respiratory, and metabolic disorders. This article reviews current information on the biological effects of EGCG in the above-mentioned disorders in relation to molecular pathways controlling inflammation, oxidative stress, and cell apoptosis.
... A clinical trial with 2g/day of green tea extract (containing 227 mg catechins and 42 mg theanine) was carried out with 15 elderly patients with MMSE-J score <28 and found that the treated group's MMSE-J score improved by 1.7 points (p=0.03) [174]. Three of the polyphenols, (-)-catechin gallate, (-)-epicatechin gallate, and (-)epigallocatechin gallate, were found to significantly decrease the aggregation of Aβ at a concentration of 10 µg ml −1 , with (-)-catechin gallate and (-)-epicatechin gallate providing more robust protection to SH-SY5Y cells against the same [161]. ...
Neurodegeneration is the progressive loss of structure or function of neurons, which may ultimately involve cell death. The most common neurodegenerative disorder in the brain happens with Alzheimer’s disease (AD) which is the most common cause of dementia. It ultimately leads to neuronal death, thereby impairing the normal functionality of the central or peripheral nervous system. The onset and prevalence of AD involve heterogeneous etiology, either in terms of genetic predisposition, neuro-metabolomic malfunctioning, or lifestyle. The worldwide relevancies are estimated to be over 45 million people. The rapid increase in AD has led to a concomitant increase in the research work, directed towards the discovery of a lucrative cure for AD. The neuropathology of AD comprises the deficiency in the availability of neurotransmitters and important neurotrophic factors in the brain, extracellular beta-amyloid plaque depositions, and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. Current pharmaceutical interventions utilizing synthetic drugs have manifested resistance and toxicity problems. This has led to the quest for new pharmacotherapeutic candidates naturally prevalent in phyto chemicals. This review aims to provide an elaborative description of promising phyto component entities having activities against various potential AD targets. Therefore, naturopathy may combine with synthetic chemotherapeutics to longer the survival of the patients. PODCAST:
... Tea drinking originated in Asia, and now it has spread throughout the world to be the most popular consumed beverage. In recent years, researchers have examined the relationship between tea intake and cognitive function [14][15][16][17][18]. Tea consumption is linked to a lower risk of cognitive impairment and dementia [14][15][16] and associated with a decrease in the progression of cognitive dysfunction [19,20]. Moreover, a study on middle-aged and older adults in China found that habitual tea consumption (especially green tea) was significantly associated with a decreased prevalence of cognitive impairment [21]. ...
Background: Previous studies suggest a positive effect of tea intake on cognition. Additional micronutrients that may moderate this association was not previously examined. Objective: To examine the association between tea consumption and cognition and explore the interaction between tea consumption and iron intake. Methods: Data from the China Health and Nutrition Survey between 1997 and 2011 was used. 4,820 individuals (≥55 years) were included in the analyses. Measurement of cognitive function was conducted in 1997, 2000, 2004, and 2006. Tea consumption was self-reported. Food intake was assessed by 24-hour dietary recalls of three consecutive days during home visits between 1997 and 2011. Multivariable mixed linear regression and logistic regression was used to assess the association. Results: Tea consumption was associated with reduced global cognitive function decline. In fully adjusted models, regression coefficients (95% CIs) for those who consumed 0 cups/day,<2 cups/day, 2-3.9 cups/day, and≥4 cups/day of tea were 0, -0.09 (-0.55-0.37), 0.05 (-0.34-0.45), and 0.87 (0.46-1.29), respectively. This effect was stronger in adults > 60 years. Tea consumption of≥4 cups/day was inversely associated with self-reported poor memory (OR 0.70 (95% CI 0.56-0.86)) and memory decline (OR, 0.73 (95% CI 0.62-0.87)). There was a significant interaction between tea consumption and iron intake in relation to cognition. High iron intake was inversely associated with cognition in non-consumers of tea but not in tea consumers. Conclusion: Higher tea intake is associated with reduced cognitive decline in adults and inhibits the adverse effect of high iron intake.
... Polyphenol research has provided evidence that they are indeed beneficial to cognitive processes in older adults (e.g. [7][8][9][10][11][12][13][14][15][16][17][18][19][20]). A premium source of polyphenols, wild blueberries are of particular interest. ...
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Background As the sector of the population over 65y increases, cognitive decline and dementia become a public health issue. Interventions to improve brain health and thus, quality of life for older adults are needed. Objective It was hypothesized that those consuming a flavonoid-rich, lyophilized wild blueberry powder would evidence improvements in cognitive performance as measured behaviorally and electrophysiologically compared to those consuming a placebo powder across a 6-month intervention period. Design In a double-blind, randomized placebo-controlled trial, participants experiencing cognitive issues as determined by scores on the Montreal Cognitive Assessment (MoCA) were randomized to consume either wild blueberry (n = 44) or placebo (n = 42) powder daily for 6 months. Participants who were not experiencing any cognitive issues were included as a reference group (n = 45). Participants were tested at baseline and outcome on the Cambridge Neurological Test Automated Battery (CANTAB) and in an electrophysiological paradigm known as event-related potentials (ERP). Results Tests of specific cognitive abilities using the CANTAB showed speed of processing not only improved in the blueberry intervention group relative to the placebo group across the 6-month intervention, but blueberries also restored speed of processing to the level of the reference group. The ERP results also showed that, relative to those consuming placebo, speed of processing improved for those in the blueberry group; this improvement was most prominent in those 75-80y. Conclusions Consumption of wild blueberries for six months improves cognitive aging sequelae by improving the speed of information processing in older adults. Trial registration: identifier: NCT01515098.
... 5,6 Beneficial effects of green tea on many human diseases have demonstrated. [7][8][9][10] It was also shown that green tea consumption decreases the risk of human cancers. [11][12][13] MicroRNAs (miRNAs) are single-stranded non-coding RNAs that have been considered to involve in various cellular pathways by negatively or positively regulating gene expression. ...
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Objective: To evaluate anticancer efficacy of green tea extract (GTE) on PC3 prostate cancer cells. Methods: By using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot methods, the expression of miR-195 and the epithelial to mesenchymal transition (EMT) markers such as E-cadherin and vimentin was analyzed. Results: Based on the results of 2D and 3D cell culture models, the inhibition of EMT and up regulation of miR-195 expression were detected. Conclusions: Our findings will be helpful to design anti-tumor regimens with natural product original, and more studies will be required to identify the related mechanisms involving anticancer activities of green tea miRNAs.
Our present knowledge about the efficacy of tea consumption in improving age-related cognitive disorders is incomplete since previous epidemiological studies provide inconsistent evidence. This unified systematic review and meta-analysis based on updated epidemiological cohort studies and randomized controlled trials (RCTs) evidence aimed to overcome the limitations of previous reviews by examining the efficacy of distinct types of tea consumption. PubMed, Embase, and MEDLINE were searched up to May 20, 2022, and 23 cohorts and 12 cross-sectional studies were included. Random-effects meta-analyses were conducted to obtain pooled RRs or mean differences with 95% CIs. The pooled RRs of the highest versus lowest tea consumption categories were 0.81 (95% CIs: 0.75-0.88) and 0.69 (95% CIs: 0.61-0.77), respectively. The pooled mean difference of four included RCTs revealed a beneficial effect of tea on cognitive dysfunction (MMSE ES: 1.03; 95% CI, 0.14-1.92). Subgroup analyses further demonstrated that green and black tea intake was associated with a lower risk of cognitive disorders in eastern countries, especially in women. The evidence quality was generally low to moderate. The present review provides insight into whether habitual tea consumption can be an effective approach against age-related neurodegenerative cognitive disorders and summarizes potential mechanisms based on currently published literature.
Alzheimer’s disease (AD) is the most common neurodegenerative disease characterized by cognitive decline and memory impairment. Many lines of evidence indicate that excessive β-amyloid peptide (Aβ) generation and aggregation play pivotal roles in the initiation of AD, leading to various biochemical alteration including oxidative damage, mitochondrial dysfunction, neuroinflammation, signaling pathway and finally resulting in neuronal death. AD has a complex pathogenic mechanism, and a single-target approach for anti-AD strategy is thus full of challenges. To overcome these limitations, the present study focused to review on one of multiple target-compounds, (–)-epigallocatechin-3-gallate (EGCG) for the prevention and treatment of AD. EGCG is a main bioactive polyphenol in green tea and has been reported to exert potent neuroprotective properties in a wide array of both cellular and animal models in AD. This review demonstrated multiple neuroprotective efficacies of EGCG by focusing on the involvement of Aβ-evoked damage and its Aβ regulation. Furthermore, to understand its mechanism of action on the brain, the permeability of the blood-brain barrier was also discussed.
Epigallocatechin gallate (EGCG) is an active catechin in green tea and has multiple biological functions, such as anti-inflammation, anti-cancer, and immune regulation. This work aimed to study the protective function of EGCG against asthma and the mechanism. Asthma in mice was induced by house dust mite (HDM) challenge. EGCG treatment alleviated tissue injury, inflammation, mucus production and collagen deposition, and it reduced M2 macrophage infiltration in mouse lung tissues induced by HDM. The bioinformatics analyses in this study suggested that target genes of EGCG were enriched in the hypoxia inducible factor-1 (HIF-1) pathway, EGCG treatment targeted HIF-1α and thereby suppressed vascular endothelial growth factor A (VEGFA) activation. Adenovirus (AAV) overexpression vectors of HIF-1α and VEGFA were administrated into mice after EGCG treatment. Either restoration of HIF-1α or VEGFA significantly blocked the protective functions of EGCG treatment against HDM-induced allergic asthma. In conclusion, this study demonstrates that EGCG treatment relieves asthmatic symptoms in mice by suppressing HIF-1α/VEGFA-mediated M2 skewing of macrophages.
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It has been proposed that green tea extract may have a beneficial impact on cognitive functioning, suggesting promising clinical implications. However, the neural mechanisms underlying this putative cognitive enhancing effect of green tea extract still remain unknown. This study investigates whether the intake of green tea extract modulates effective brain connectivity during working memory processing and whether connectivity parameters are related to task performance. Using a double-blind, counterbalanced, within-subject design, 12 healthy volunteers received a milk whey-based soft drink containing 27.5 g of green tea extract or a milk whey-based soft drink without green tea as control substance while undergoing functional magnetic resonance imaging. Working memory effect on effective connectivity between frontal and parietal brain regions was evaluated using dynamic causal modeling. Green tea extract increased the working memory induced modulation of connectivity from the right superior parietal lobule to the middle frontal gyrus. Notably, the magnitude of green tea induced increase in parieto-frontal connectivity positively correlated with improvement in task performance. Our findings provide first evidence for the putative beneficial effect of green tea on cognitive functioning, in particular, on working memory processing at the neural system level by suggesting changes in short-term plasticity of parieto-frontal brain connections. Modeling effective connectivity among frontal and parietal brain regions during working memory processing might help to assess the efficacy of green tea for the treatment of cognitive impairments in psychiatric disorders such as dementia.
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Previous studies have demonstrated that repeated administration of the exogenous stress hormone corticosterone (CORT) induces dysregulation in the hypothalamic-pituitary-adrenal (HPA) axis and results in depression and anxiety. The current study sought to verify the impact of catechin (CTN) administration on chronic CORT-induced behavioral alterations using the forced swimming test (FST) and the elevated plus maze (EPM) test. Additionally, the effects of CTN on central noradrenergic systems were examined by observing changes in neuronal tyrosine hydroxylase (TH) immunoreactivity in rat brains. Male rats received 10, 20, or 40 mg/kg CTN (i.p.) 1 h prior to a daily injection of CORT for 21 consecutive days. The activation of the HPA axis in response to the repeated CORT injections was confirmed by measuring serum levels of CORT and the expression of corticotrophin-releasing factor (CRF) in the hypothalamus. Daily CTN administration significantly decreased immobility in the FST, increased open-arm exploration in the EPM test, and significantly blocked increases of TH expression in the locus coeruleus (LC). It also significantly enhanced the total number of line crossing in the open-field test (OFT), while individual differences in locomotor activities between experimental groups were not observed in the OFT. Taken together, these findings indicate that the administration of CTN prior to high-dose exogenous CORT significantly improves helpless behaviors, possibly by modulating the central noradrenergic system in rats. Therefore, CTN may be a useful agent for the treatment or alleviation of the complex symptoms associated with depression and anxiety disorders.
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A systematic literature review of human studies relating caffeine or caffeine-rich beverages to cognitive decline reveals only 6 studies that have collected and analyzed cognition data in a prospective fashion that enables study of decline across the spectrum of cognition. These 6 studies, in general, evaluate cognitive function using the Mini Mental State Exam and base their beverage data on FFQs. Studies included in our review differed in their source populations, duration of study, and most dramatically in how their analyses were done, disallowing direct quantitative comparisons of their effect estimates. Only one of the studies reported on all 3 exposures, coffee, tea, and caffeine, making comparisons of findings across studies more difficult. However, in general, it can be stated that for all studies of tea and most studies of coffee and caffeine, the estimates of cognitive decline were lower among consumers, although there is a lack of a distinct dose response. Only a few measures showed a quantitative significance and, interestingly, studies indicate a stronger effect among women than men.
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Objective: We examined the longitudinal association between tea drinking frequency and cognitive function in a large sample of oldest-old Chinese. Design: population-based longitudinal cohort study. Setting: The Chinese Longitudinal Healthy Longevity Survey (CLHLS). Participants: 7139 participants aged 80 to 115 (mean age 91.4 years) who provided complete data at baseline (year 1998). Measurements: Current frequency of tea drinking and past frequency at age 60 were ascertained at baseline, and baseline and follow-up cognitive assessments were performed in the years 1998 (n=7139), 2000 (n=4081), 2002 (n=2288) and 2005 (n=913) respectively. Verbal fluency test was used as measure of cognitive function. Results: Tea drinking was associated at baseline with higher mean (SD) verbal fluency scores: daily=10.7 (6.6), occasional=9.2 (5.8), non-drinker=9.0 (5.5). In linear mixed effects model that adjusted for age, gender, years of schooling, physical exercise and activities score, the regression coefficient for daily drinking (at age 60) and occasional drinking was 0.72 (P<0.0001) and 0.41(P=0.01) respectively. Tea drinkers had higher verbal fluency scores throughout the follow-up period but concurrently had a steeper slope of cognitive decline as compared with non-drinkers (coefficient for the interaction term Time*Daily drinking= -0.12, P=0.02; "Time" was defined as the time interval from baseline to follow-up assessments in years). Similar results were found for current tea drinking status at study baseline year (1998) as predictor variable. Conclusion: Regular tea drinking is associated with better cognitive function in oldest-old Chinese.
To examine the association between tea consumption and depressive symptoms in Chinese older people and to explore the mediating role of cerebrovascular disease in the association. Population-based cross-sectional study. A rural community near Qufu in Shandong, China. Community-dwelling individuals aged 60 and older (mean 68.6; 59.3% female) from the Confucius Hometown Aging Project (N = 1,368). Data were collected through interviews, clinical examinations, and psychological testing, following a standard procedure. Presence of high depressive symptoms was defined as a score of 5 or greater on the 15-item Geriatric Depression Scale. Of the 1,368 participants, 165 (12.1%) were weekly and 489 (35.7%) were daily tea consumers. Compared with no or irregular tea consumption, controlling for age, sex, education, leisure activities, number of comorbidities, and Mini-Mental State Examination score, the odds ratios of having high depressive symptoms were 0.86 (95% confidence interval (CI) = 0.56-1.32) for weekly and 0.59 (95% CI = 0.43-0.81) for daily tea consumption (P for linear trend = .001); the linear trend of the association remained statistically significant when further controlling for history of stroke, transient ischemic attacks, and presence of carotid plaques. Daily tea consumption is associated with a lower likelihood of depressive symptoms in Chinese older people living in a rural community. The association appears to be independent of cerebrovascular disease and atherosclerosis.
The evidence base on the prevalence of dementia is expanding rapidly, particularly in countries with low and middle incomes. A reappraisal of global prevalence and numbers is due, given the significant implications for social and public policy and planning. In this study we provide a systematic review of the global literature on the prevalence of dementia (1980-2009) and metaanalysis to estimate the prevalence and numbers of those affected, aged ≥60 years in 21 Global Burden of Disease regions. Age-standardized prevalence for those aged ≥60 years varied in a narrow band, 5%-7% in most world regions, with a higher prevalence in Latin America (8.5%), and a distinctively lower prevalence in the four sub-Saharan African regions (2%-4%). It was estimated that 35.6 million people lived with dementia worldwide in 2010, with numbers expected to almost double every 20 years, to 65.7 million in 2030 and 115.4 million in 2050. In 2010, 58% of all people with dementia lived in countries with low or middle incomes, with this proportion anticipated to rise to 63% in 2030 and 71% in 2050. The detailed estimates in this study constitute the best current basis for policymaking, planning, and allocation of health and welfare resources in dementia care. The age-specific prevalence of dementia varies little between world regions, and may converge further. Future projections of numbers of people with dementia may be modified substantially by preventive interventions (lowering incidence), improvements in treatment and care (prolonging survival), and disease-modifying interventions (preventing or slowing progression). All countries need to commission nationally representative surveys that are repeated regularly to monitor trends.
Background: Tea leaves contain varying amounts of polyphenols of which the majority are catechins. There has been a sizable amount of research on the potential effect of green tea catechins for cancer risk, cardiovascular disease risk and weight loss; all conditions that are relevant to mid-life health. The aim was to produce an overview of the evidence for green tea for these three important health conditions. Methods: The databases Medline (& Medline in process) and Embase, were searched for systematic reviews and meta-analyses using customised search strategies performed up until April 2012. Assessment of Multiple Systematic Reviews criteria were used to assess the quality of the included reviews. Relevant data were extracted into predefined tables. The results are described and discussed narratively. Results: We included eight systematic reviews and meta-analyses covering the topics of cancer risk (n=2), cardiovascular risk (n=4) and weight loss (n=2). Conclusions: The evidence for green tea and cancer risk is inadequate and inconclusive. However there is some positive evidence for risk reduction of breast, prostate, ovarian and endometrial cancers with green tea. RCTs of green tea and cardiovascular risk factors suggest that green tea may reduce low-density lipoproteins and total cholesterol, although studies are of short duration. There is no robust evidence to support a reduction in coronary artery disease risk in green tea drinkers. There are a considerable number of RCTs to suggest that green tea does reduce body weight in the short term, but this not likely to be of clinical relevance.