18 december 2017: Een reviewstudie en meta analyse ( Green tea and the risk of prostate cancer ) naar de effecten van groene thee als preventie van prostaatkanker en PSA waarden bevestigt dat dagelijks enkele koppen groene thee drinken prostaatkanker kan voorkomen en PSA waarden binnen normaal kan houden.
Conclusie van de onderzoekers:
Voorzover ons bekend is dit de eerste meta-analyse van de consumptie van groene thee-catechinen en de incidentie van prostaatkanker (PCa). Ook voerden we een dosis-respons-meta-analyse uit om systematisch en kwantitatief de associatie van groene thee-inname met PCa-risico te evalueren. Onze nieuwe gegevens toonden aan dat consumptie van groene thee de incidentie van PCa met een lineair dosisresponseffect kan verminderen en dat een inname van meer dan 7 kopjes / dag het PCa-risico significant verlaagde en groene theecatechinen mogelijk effectief zijn om PCa te voorkomen.
Onderaan artikel referentielijst behorend bij deze reviewstudie
Hier de grafiek uit die reviewstudie over het risico op prostaatkanker:
Forest plot for the association of highest versus lowest category of green tea intake and PCa. The association was indicated as RR with the corresponding 95% CI. The RR estimate of each study is marked with a solid black square. The size of the square represents the weight that the corresponding study exerts in the meta-analysis. The CIs of pooled estimates are displayed as a horizontal line through the diamond. RR < 1 indicates decreased risk of PCa. CI = confidence interval, PCa = prostate cancer, RR = relative risk
2 november 2012: Groene thee heeft mits goed gezet en de juiste groene verse thee gebruikt een hoog gehalte van polyfenolen, is gemakkelijk te maken en in te nemen en is op grote schaal beschikbaar. In het boek Eten tegen Kanker kunt u lezen hoe groene thee te maken en welke soorten het beste zijn.
23 november 2006: Bron: 1: Cancer Res. 2006 Jan 15;66(2):1234-40.
Opnieuw bewijst groene thee sterk preventief tegen kanker te zijn bij mannen met een sterk vergroot risico op prostaatkanker door aanwezigheid van afwijkingen aan de prostaat welke vaak leiden tot prostaatkanker. Als vervolg op een soortgelijke studie uit 2005 werd een nieuwe 1 jarige gerandomiseerde placebo gecontroleerde studie opgezet met opnieuw 60 mannen met een sterk vergroot risico op prostaatkanker. Uit de groep die groene thee kreeg te drinken ontwikkelde slechts 1 man prostaatkanker (3%). In de placebogroep kregen negen mannen prostaatkanker. (30%) Een statistisch significant verschil in effectiviteit en bevestigt de resultaten uit de studie uit 2005.
Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study.
Bettuzzi S, Brausi M, Rizzi F, Castagnetti G, Peracchia G, Corti A.
Department of Medicina Sperimentale, Sezione di Biochimica, University of Parma, Via Volturno 39, 43100 Parma, Italy. firstname.lastname@example.org
Green tea catechins (GTCs) proved to be effective in inhibiting cancer growth in several experimental models. Recent studies showed that 30% of men with high-grade prostate intraepithelial neoplasia (HG-PIN) would develop prostate cancer (CaP) within 1 year after repeated biopsy. This prompted us to do a proof-of-principle clinical trial to assess the safety and efficacy of GTCs for the chemoprevention of CaP in HG-PIN volunteers. The purity and content of GTCs preparations were assessed by high-performance liquid chromatography [(-)-epigallocathechin, 5.5%; (-)-epicatechin, 12.24%; (-)-epigallocatechin-3-gallate, 51.88%; (-)-epicatechin-3-gallate, 6.12%; total GTCs, 75.7%; caffeine, <1%]. Sixty volunteers with HG-PIN, who were made aware of the study details, agreed to sign an informed consent form and were enrolled in this double-blind, placebo-controlled study. Daily treatment consisted of three GTCs capsules, 200 mg each (total 600 mg/d). After 1 year, only one tumor was diagnosed among the 30 GTCs-treated men (incidence, approximately 3%), whereas nine cancers were found among the 30 placebo-treated men (incidence, 30%). Total prostate-specific antigen did not change significantly between the two arms, but GTCs-treated men showed values constantly lower with respect to placebo-treated ones. International Prostate Symptom Score and quality of life scores of GTCs-treated men with coexistent benign prostate hyperplasia improved, reaching statistical significance in the case of International Prostate Symptom Scores. No significant side effects or adverse effects were documented. To our knowledge, this is the first study showing that GTCs are safe and very effective for treating premalignant lesions before CaP develops. As a secondary observation, administration of GTCs also reduced lower urinary tract symptoms, suggesting that these compounds might also be of help for treating the symptoms of benign prostate hyperplasia.
PMID: 16424063 [PubMed - indexed for MEDLINE]
In summary, our meta-analysis indicated green tea intake might reduce the incidence of PCa with a linear dose–response effect and decrease PCa risk significantly with over 7 cups/day. This was further confirmed by the potential protective effect of green tea catechins on PCa. Further prospective study with accurate measurement of green tea intake is required to substantiate these conclusions.
Green tea and the risk of prostate cancer
A systematic review and meta-analysis
Monitoring Editor: Sumit Arora.
Prostate cancer (PCa) now remains the 2nd most frequently diagnosed cancer. In recent years, chemoprevention for PCa becomes a possible concept. Especially, many phytochemicals rich foods are suggested to lower the risk of cancer. Among these foods, green tea is considered as effective prevention for various cancers. However, clinical trials and previous meta-analyses on the relationship between green tea consumption and the risk of PCa have produced inconsistent outcomes. This study aims to determine the dose–response association of green tea intake with PCa risk and the preventive effect of green tea catechins on PCa risk. Seven observational studies and 3 randomized controlled trials were retrieved from Cochrane Library, PubMed, Sciencedirect Online, and hand searching. The STATA (version 12.0) was applied to analyze the data. The relative risks (RRs) and 95% confidence intervals were pooled by fixed or random effect modeling. Dose–response relations were evaluated with categories of green tea intake. Although there was no statistical significance in the comparison of the highest versus lowest category, there was a trend of reduced incidence of PCa with each 1 cup/day increase of green tea (P = 0.08). Our dose–response meta-analysis further demonstrated that higher green tea consumption was linearly associated with a reduced risk of PCa with more than 7 cups/day. In addition, green tea catechins were effective for preventing PCa with an RR of 0.38 (P = 0.02). In conclusion, our dose–response meta-analysis evaluated the association of green tea intake with PCa risk systematically and quantitatively. And this is the first meta-analysis of green tea catechins consumption and PCa incidence. Our novel data demonstrated that higher green tea consumption was linearly reduced PCa risk with more than 7 cups/day and green tea catechins were effective for preventing PCa. However, further studies are required to substantiate these conclusions.
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