Health and tea

Health and Tea

Other medical areas

European Journal of Clinical Nutrition66, 1187-1192 (November 2012)

 

 

Neural effects of green tea extract on dorsolateral prefrontal cortex

S Borgwardt,F Hammann,K Scheffler,M Kreuter,J DreweandC Beglinger

 

Background/objectives:

Green tea is being recognized as a beverage with potential benefits for human health and cognitive functions. In vivo studies provide preliminary evidence that green tea intake may have a positive role in improving effects on cognitive functions. We aimed to examine the neural effects of green tea extract on brain activation in humans.

Subjects/methods:

Functional magnetic resonance imaging was recorded while 12 healthy volunteers performed a working memory task following administration of 250 or 500ml of a milk whey based green tea containing soft drink or milk whey based soft drink without green tea as control in a double-blind, controlled repeated measures within-subject design with counterbalanced order of substance administration. A whole-brain analysis with a cluster-level threshold of P<0.001 (unadjusted) was followed by an a priori-defined region of interest (ROI) analysis of the dorsolateral prefrontal cortex (DLPFC) including a cluster-level threshold of P<0.05 and family-wise error (FWE) adjustment for multiple comparisons.

Results:

Whole-brain analyses revealed no significant effects after correction for multiple comparisons (FWE P<0.05). Using a ROI approach, green tea extract increased activation in the DLPFC relative to a control condition (FWE P<0.001). This neural effect was related to green tea dosage. Green tea extract was not associated with any significant attenuation in regional activation relative to control condition.

Conclusions:

These data suggest that green tea extract may modulate brain activity in the DLPFC, a key area that mediates working memory processing in the human brain. Moreover, this is the first neuroimaging study implicating that functional neuroimaging methods provide a means of examining how green tea extract acts on the brain.

 

US NATIONAL LIBRARY OF MEDICINE NATIONAL INSTITUTES OF HEALTH

Arthritis Res Ther. 2011 Aug 10;13(4):121. 

Katiyar SKRaman C. 

Green tea: a new option for the prevention or control of osteoarthritis.

ABSTRACT: IL-1? is a major cytokine driving the inflammatory processes leading to the pathophysiology of osteoarthritis and other inflammatory diseases. Blockade of IL-1? activity using substances such as the naturally occurring IL-1 receptor antagonist or anti-IL-1? monoclonal antibody are currently being used or tested as therapy. However, such treatments are ineffective in osteoarthritis. In a recent study, epigallocatechin-3-gallate, a green tea polyphenol, was found to be effective in reducing IL-1?-induced inflammatory cytokines, TNF?, IL-6, granulocyte-macrophage colony-stimulating factor and several chemokines from human chondrocytes. The use of green tea polyphenols may be beneficial as a therapeutic addition to biologics that control IL-1? activity by increasing effectiveness and/or reducing dosage.

 

BPG

British Photodermatology Group

Photodermatology, Photoimmunology & Photomedicine

 

http://www.bpg.org.uk/about/

http://www.blackwellpublishing.com/journal.asp?ref=0905-4383&site=1

 

Volume 21, Issue 1, Pages 15-22 (February 2005)

 

 

Morley N, Clifford T, Salter L, Campbell S, Gould D, Curnow A.

The green tea polyphenol (-)-epigallocatechin gallate and green tea can protect human cellular DNA from ultraviolet and visible radiation-induced damage.

Cornwall Dermatology Research Project, RoyalCornwallHospital, Truro, Cornwall, UK.

BACKGROUND: Antioxidant compounds in green tea may be able to protect against skin carcinogenesis and it is of interest to investigate the mechanisms involved. A study was therefore conducted to determine whether the isolated green tea polyphenol (-)-epigallocatechin gallate (EGCG) could prevent ultraviolet radiation (UVR)-induced DNA damage in cultured human cells. This work was then extended to investigate whether drinking green tea could afford any UVR protection to human peripheral blood cells collected after tea ingestion. METHODS: The alkaline comet assay was used to compare the DNA damage induced by UVR in cultured human cells with and without the presence of EGCG. The same assay technique was then employed to assess UVR-induced DNA damage in peripheral leucocytes isolated from 10 adult human volunteers before and after drinking 540 ml of green tea. RESULTS: Initial trials found that EGCG afforded concentration-dependent photoprotection to cultured human cells with a maximal activity at a culture concentration of 250 microM. The cells types tested (lung fibroblasts, skin fibroblasts and epidermal keratinocytes) demonstrated varying susceptibility to the UVR insult provided. The in vivo trials of green tea also demonstrated a photoprotective effect, with samples of peripheral blood cells taken after green tea consumption showing lower levels of DNA damage than those taken prior to ingestion when exposed to 12 min ultraviolet A (UVA) radiation. CONCLUSION: The studies showed that green tea and/or some constituents can offer some protection against UV-induced DNA damage in human cell cultures and also in human peripheral blood samples taken post-tea ingestion.

 

Read more http://www.blackwell-synergy.com/doi/abs/10.1111/j.1600-0781.2005.00119.x

 

 

AMERICAN COLLEGE OF PHYSICIANS

Annals of Internal Medicine

http://www.acponline.org/

http://www.annals.org/

 

Volume 144, Issue 8, Pages 554-562 (April 2006)

 

Iso H, Date C, Wakai K, Fukui M, Tamakoshi A; JACC Study Group.


The relationship between green tea and total caffeine intake and risk for self-reported type 2 diabetes among Japanese adults.


Department of Social and Environmental Health, OsakaUniversity and OsakaCityUniversity, Osaka, Japan.

 

BACKGROUND: In western populations, coffee consumption is associated with a reduced risk for type 2 diabetes; however, the effect of green, black, and oolong teas is unclear. OBJECTIVE: To examine the relationship between consumption of these beverages and risk for diabetes. DESIGN: Retrospective cohort study. SETTING: 25 communities across Japan. PARTICIPANTS: A total of 17,413 persons (6727 men and 10,686 women; 49% of the original study population) who were 40 to 65 years of age; had no history of type 2 diabetes, cardiovascular disease, or cancer at the baseline lifestyle survey; and completed the 5-year follow-up questionnaire. There was no difference in body mass index levels at baseline between respondents and nonrespondents. MEASUREMENTS: Questionnaire on consumption of coffee; black, green, and oolong teas; and physician-diagnosed diabetes. RESULTS: During the 5-year follow-up, there were 444 self-reported new cases of diabetes in 231 men and 213 women (5-year event rates, 3.4% and 2.0%, respectively). Consumption of green tea and coffee was inversely associated with risk for diabetes after adjustment for age, sex, body mass index, and other risk factors. Multivariable odds ratios for diabetes among participants who frequently drank green tea and coffee (> or =6 cups of green tea per day and > or =3 cups of coffee per day) were 0.67 (95% CI, 0.47 to 0.94) and 0.58 (CI, 0.37 to 0.90), respectively, compared with those who drank less than 1 cup per week. No association was found between consumption of black or oolong teas and the risk for diabetes. Total caffeine intake from these beverages was associated with a 33% reduced risk for diabetes. These inverse associations were more pronounced in women and in overweight men. LIMITATIONS: Diabetes was self-reported, no data were available on consumption of soda, and the follow-up rate was low. CONCLUSIONS: Consumption of green tea, coffee, and total caffeine was associated with a reduced risk for type 2 diabetes.

 

Read more http://www.annals.org/cgi/reprint/144/8/554.pdf

 

 

 

EJCN

European Journal of Clinical Nutrition

http://www.nature.com/ejcn/index.html

 

Volume 61, Issue 1, Pages 3-18 (January 2007)

 

Gardner EJ, Ruxton CH, Leeds AR.

 

Black tea - helpful or harmful? A review of the evidence.

 

King's College London, Department of Nutrition & Dietetics, London, UK.


Objective: To consider whether consumption of black tea has a positive or negative impact on health. Design: Databases were searched for relevant epidemiological and clinical studies published between 1990 and 2004.Results:Clear evidence was found for coronary heart disease (CHD), where an intake of >/=3 cups per day related to risk reduction. The mechanism could involve the antioxidant action of tea polyphenols. While experimental models have suggested that flavonoids attenuated cancer risk, epidemiological studies failed to demonstrate a clear effect for tea, although there is moderate evidence for a slightly positive or no effect of black tea consumption on colorectal cancer. Studies on cancer were limited by sample sizes and insufficient control of confounders. There is moderate evidence suggestive of a positive effect of black tea consumption on bone mineral density although studies were few. There is little evidence to support the effect of tea on dental plaque inhibition but evidence to support the contribution of tea to fluoride intakes and thus theoretical protection against caries. There was no credible evidence that black tea (in amounts typically consumed) was harmful. Normal hydration was consistent with tea consumption when the caffeine content was <250 mg per cup. A moderate caffeine intake from tea appeared to improve mental performance, although sample sizes were small. There was no evidence that iron status could be harmed by tea drinking unless populations were already at risk from anaemia. Conclusions: There was sufficient evidence to show risk reduction for CHD at intakes of >/=3 cups per day and for improved antioxidant status at intakes of one to six cups per day. A maximum intake of eight cups per day would minimise any risk relating to excess caffeine consumption. Black tea generally had a positive effect on health. Sponsorship:The Tea Council. The authors confirm that the sponsors played no role in the writing of this review.

 

http://www.nature.com/ejcn/journal/v61/n1/full/1602489a.html