Green tea and black tea consumption and prostate cancer risk: an exploratory meta-analysis of observational studies

Observational studies on tea consumption and prostate cancer (PCa) risk are still inconsistent. The authors conducted a meta-analysis to investigate the association between green tea and black tea consumption with PCa risk. Thirteen studies providing data on green tea or black tea consumption were identified by searching PubMed and ISI Web of Science databases and secondary referencing qualified for inclusion. A random-effects model was used to calculate the summary odds ratios (OR) and their corresponding 95% confidence intervals (CIs). For green tea, the summary OR of PCa indicated a borderline significant association in Asian populations for highest green tea consumption vs. non/lowest (OR = 0.62; 95% CI: 0.38-1.01); and the pooled estimate reached statistically significant level for case-control studies (OR = 0.43; 95% CI: 0.25-0.73), but not for prospective cohort studies (OR = 1.00; 95% CI: 0.66-1.53). For black tea, no statistically significant association was observed for the highest vs. non/lowest black tea consumption (OR = 0.99; 95% CI: 0.82-1.20). In conclusion, this meta-analysis supported that green tea but not black tea may have a protective effect on PCa, especially in Asian populations. Further research regarding green tea consumption across different regions apart from Asia is needed.     

Green Tea Consumption and Risk of Pancreatic Cancer: A Meta-analysis

Emerging laboratory and animal studies indicate that green tea inhibits development and progression of pancreatic cancer, but evidence from epidemiologic studies appears inconsistent and inconclusive. A meta-analysis summarizing published case-control and cohort studies was performed to evaluate the association of green tea consumption with risk of pancreatic cancer. Pertinent studies were identified by a search of PubMed and EMBASE up to April 2014. A random-effects model was assigned to compute summary risk estimates. A total of three case-control studies and five prospective studies were included, comprising 2317 incident cases and 288209 subjects. Of them, three studies were from China and the reminders were conducted in Japan. Overall, neither high vs. low green consumption (odds ratio (OR) = 0.99, 95% confidence interval [CI] = 0.78–1.25), nor an increase in green tea consumption of two cups/day (OR = 0.95, 95% CI = 0.85–1.06) was associated with risk of pancreatic cancer. The null association persisted when the analysis was stratified by sex or restricted to non-smokers. In the stratification by study location, the summary OR for the studies from China and for those from Japan was 0.77 (95% CI = 0.60–0.99) and 1.21 (95% CI = 0.94–1.54), respectively (P for differences = 0.04). Cumulative epidemiologic evidence suggests that green tea consumption is not associated with pancreatic cancer.     

Meta-Analysis of Black Tea Consumption and Breast Cancer Risk: Update 2013

Black tea is a commonly consumed beverage in the world, comprising approximately 80% of all tea consumed. We sought to examine the association between black tea consumption and risk of breast cancer, using all available epidemiologic evidence to date. PubMed, EMBASE, ISI Web of Science, Chinese National Knowledge Infrastructure Database, and China Biological Medicine Database were used to search for citations using the MeSH terms as “breast neoplasm” AND “black tea.” Then we performed a meta-analysis of studies of breast cancer risk published between 1985 and 2013 by using RevMan 5.0 software. The results showed that no association between black tea consumption and breast cancer risk in overall [odds ratio (OR) = 0.97; 95% confidence interval (CI) = 0.89–1.05]. We further performed a stratified analysis according to region (United States/Europe). Black tea consumption did not decrease breast cancer risk in the United States (OR = 0.91; 95% CI = 0.78–1.07) and in Europe (OR = 0.99; 95% CI = 0.93–1.06). In addition, the summary OR from all cohort studies (OR = 1.04, 95% CI = 0.91–1.18) or all case-control studies (OR = 0.95, 95% CI = 0.88–1.02) showed black tea intake has no effects on breast cancer risk. However, the association between black tea consumption and breast cancer incidence remains unclear based on the current evidence. Further well-designed large studies are needed to confirm our result.     

Dairy Consumption and Gastric Cancer Risk: A Meta-Analysis of Epidemiological Studies

Studies investigating the association of dairy consumption with gastric cancer risk have reported inconsistent findings. We conducted this systematic review and meta-analysis to review and summarize the epidemiologic evidence on the relation of total dairy and milk consumption with risk of gastric cancer. We summarized the available literature on this topic using meta-analysis of relative risks (RR) associated with total dairy and milk intake. The total of 17 case-control and 6 cohort studies (3256 cases) were eligible for inclusion. When comparing the highest with the lowest category of total dairy intake, the results of cohort studies indicated that increased consumption of total dairy food was associated with a reduced risk of gastric cancer (RR = 0.76; 95% CI: 0.64–0.91), whereas case-control studies provided no association. In subgroup analysis, significantly inverse associations between total diary food consumption and gastric cancer risk were observed in Europe subgroup (RR = 0.73; 95% CI: 0.54–0.99), U.S. subgroup (RR = 0.78; 95% CI: 0.63–0.98) but not in Asia subgroup. However, milk consumption was not associated with gastric cancer risk no matter in main or subgroup analysis. The results of cohort studies, but not case-control studies, suggested that total dairy might be related to the reduction of gastric cancer risk. Milk consumption was not associated with gastric cancer risk.     

Consumption of Tea and Risk for Pancreatic Cancer: A Meta-Analysis of Published Epidemiological Studies

Epidemiologic studies on the relationship between tea consumption and pancreatic cancer are inconsistent. Therefore, we conducted a systematic search of databases and performed a meta-analysis to analyze the association between tea consumption and risk of pancreatic cancer. We searched Medline, EMBASE, ISI Web of Science, and the Cochrane library for studies of tea consumption and pancreatic cancer published up to December 2012. Subgroup analysis was conducted by study type, study region, sex, type of tea, without or with adjustment for smoking, and body mass index. We performed a meta-analysis of 8 case-control studies and 6 cohort studies. For pancreatic cancer, the summary odds ratio (OR) for highest vs. lowest was 0.95 (95% confidence interval (CI), 0.84–1.08). The summary OR for moderate vs. lowest was 1.07 (95% CI, 0.86–1.35). The summary OR for ever vs. lowest was 1.00 (95% CI, 0.86–1.16). The results of this meta-analysis suggested tea consumption is not related to pancreatic cancer risk, even at high doses. Because of the small number of studies, further prospective studies are needed.     

Are coffee and tea consumption associated with urinary tract cancer risk? A systematic review and meta-analysis

BACKGROUND: Narrative reviews have concluded that there is a small association between coffee consumption and an increased risk of urinary tract cancer, possibly due to confounding by smoking. No association for tea consumption has been indicated. This systematic review attempts to summarize and quantify these associations both unadjusted and adjusted for age, smoking and sex. METHOD: Thirty-four case-control and three follow-up studies were included in this systematic review. Summary odds ratios (OR) were calculated by meta-regression analyses. RESULTS: The unadjusted summary OR indicated a small increased risk of urinary tract cancer for current coffee consumers versus non-drinkers. The adjusted summary OR were: 1.26 (95% CI : 1.09-1.46) for studies with only men, 1.08 (95% CI : 0.79-1.46) for studies with only women and 1.18 (95% CI : 1.01-1.38) for studies with men and women combined. Neither unadjusted nor adjusted summary OR provided evidence for a positive association between tea consumption and urinary tract cancer. Even though studies differed in methodology, the results were rather consistent. We did not perform dose-response analyses for coffee and tea consumption due to sparse data. CONCLUSIONS: In accordance with earlier reviews, we found that coffee consumption increases the risk of urinary tract cancer by approximately 20%. The consumption of tea seems not to be related to an increased risk of urinary tract cancer.     

Black tea consumption and risk of rectal cancer in Moscow population

PURPOSE: This population-based case-control study (663 cases and 323 controls) examined the effect of black tea intake on the risk of rectal cancer in Moscow residents. The Moscow population was selected for its wide range of black tea consumption. METHODS: This study used three measures of tea consumption: the volume of beverage (l/month), zavarka (tea concentrate, l/month), and dry tea (g/month). We calculated the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for these three parameters of tea intake using logistic regression. RESULTS: Greater use of dry tea was associated with lower risk of rectal cancer in women (high vs. low: OR = 0.40; 95% CI, 0.23-0.70) and in men (high vs. low: OR = 0.77; 95% CI, 0.42-1.43). The observed effect was weaker when tea was measured as zavarka (high vs. low in women: OR = 0.47; 95% CI, 0.26-0.83; in men: OR = 0.99; 95% CI, 0.52-1.96) and as beverage volume (high vs. low in women: OR = 0.68; 95% CI, 0.39-1.19; in men: OR = 1.03; 95% CI, 0.53-2.09). CONCLUSIONS: These findings support the hypothesis that black tea consumption reduces the risk of rectal cancer. The attenuation of the effect across the three measures of tea intake can be explained by an increasing degree of exposure misclassification from dry tea to zavarka and beverage volume.     

饮食与胃癌关系的病例对照研究

目的探讨鱼露摄入及饮食、生活习惯与胃癌发生的关系。方法１９９４年５月～１９９５年７月，在胃癌高发区福建省长乐、福清两市，进行以人群为基础１２配对的病例对照研究。共调查２７２对。结果危险状态的单因素检验提示，过量摄入鱼露（ＯＲ＝２．５７）、腌制蔬菜（ＯＲ＝１．４１）、腌制海产品（ＯＲ＝１．５７），少吃新鲜蔬菜（ＯＲ＝１．９５）、柑桔类水果（ＯＲ＝１．４１）、其他水平（ＯＲ＝１．３１）、绿茶（ＯＲ＝１．７２），以及暴露于霉粮（ＯＲ＝２．３２）、三餐不定时（ＯＲ＝５．４７）、家族肿瘤史（ＯＲ＝３．２７）等与胃癌的发生存在显著性正关联。未发现吸烟、饮酒、盐摄入量、使用冰箱等与胃癌间的联系。危险状态的条件Ｌｏｇｉｓｔｉｃ回归分析，入选最佳子集的因素为鱼露、腌制海产品、三餐不定时和家族肿瘤史。４个因素的综合归因危险度为７５．４９％。结论过量摄入鱼露、腌制食品、霉粮，及三餐不定时、家族肿瘤史等可能是当地胃癌高发的危险因素。而新鲜蔬菜、水果，绿茶等可能具有保护作用。     

A population-based case-control study of lung cancer and green tea consumption among women living in Shanghai, China.

Epidemiologic evidence regarding the association between the consumption of green tea and lung cancer is limited and inconclusive, although experimental studies have shown consistently that tea preparations and tea polyphenols may inhibit the induction of a variety of cancers, including lung cancer. In this population-based case-control study, we examined the association between past consumption of green tea and the risk of lung cancer. We identified 649 incident cases of primary lung cancer among women diagnosed from February 1992 through January 1994 using the population-based Shanghai Cancer Registry. We randomly selected a control group of 675 women from the Shanghai Residential Registry, frequency-matched to the expected age distribution of the cases. Green tea consumption was ascertained through face-to-face interviews. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) using unconditional logistic regression. Among nonsmoking women, consumption of green tea was associated with a reduced risk of lung cancer (OR = 0.65; 95% CI = 0.45-0.93), and the risks decreased with increasing consumption. We found little association, however, among women who smoked (OR = 0.94; 95% CI = 0.40-2.22). The inconsistency in the association between drinking tea and the risk of lung cancer reported in previous studies may in part be due to inadequate control of confounding of active smoking.     

绿茶与子宫内膜癌关系的病例对照研究

目的探讨饮茶特别是绿茶与子宫内膜癌的关系。方法采用以人群为基础的病例对照研究,调查上海市1997年1月至2002年12月间已确诊年龄30～69岁的子宫内膜癌患者(n=995)和全人群对照(n=1087)的一般情况、月经生育史、饮食及营养素、个人生活习惯、激素相关因素、疾病及家族史等资料,采用非条件logistic回归模型分析饮茶与子宫内膜癌的关系。结果与从未饮茶者相比,有饮茶史者患子宫内膜癌的危险略降低(OR=0.82,P=0.0466)。饮茶主要对绝经前女性有保护作用(OR=0.74,95%CI:0.54～1.01);以从不饮茶者为参比组,饮淡茶、浓淡适中及浓茶者的OR值分别为0.72、0.88和0.44,趋势检验有统计学意义(P=0.0431)。在不吸烟不饮酒者中,饮绿茶对子宫内膜癌有保护作用(OR=0.77,P=0.0199);每周饮绿茶频率越高,患子宫内膜癌的危险性越低;以从未饮茶者为参比组,每周饮绿茶<7次及≥7次者OR值分别为0.90(95%CI:0.53～1.54)和0.76(95%CI:0.60～0.95),趋势检验P=0.0163;饮绿茶量越大危险性越低,每月饮绿茶≤100g、～200g及>200g者的OR值分别为0.76、0.87和0.74,趋势检验有统计学意义。结论饮茶特别是绿茶对子宫内膜癌可能有弱的保护作用,且该作用可能局限于绝经前女性。     

Citrus fruits intake and prostate cancer risk: a quantitative systematic review

OBJECTIVES: The purpose of this systematic review was to investigate the association between dietary intake of citrus fruits and prostate cancer risk. METHODS: Authors searched electronic databases and the reference lists of publications of diet and prostate cancer studies until August 2007. All of the epidemiological studies that obtained individual data on dietary intake of citrus fruits and presented risk estimates of the association between intake of citrus fruits and risk of prostate cancer were identified and included. Using general variance-based methods, study-specific odds ratios (OR)/ relative risk (RR) and associated confidence interval (CI)/ standard error (SE) for highest versus lowest intake of citrus fruits level were extracted from each paper. RESULTS: Eleven articles including six case-control studies, one nested case-control study and four cohort studies, proved eligible. Overall summary OR using random effect model did not show an association in risk of prostate cancer with intake of citrus fruits (summary OR=1.03, 95% CI=0.89-1.19) with large heterogeneity across studies that we were unable to explain (I(2)=67.88%). The summary ORs in case-control studies and cohort studies were 1.10 (95% CI=0.97-1.22) and 1.05 (95% CI=0.96-1.14), respectively. CONCLUSIONS: Pooled results from observational studies did not show an association between intake of citrus fruits and the risk of prostate cancer, although results vary substantially across studies.     

Green Tea Consumption and Risk of Esophageal Cancer: A Meta-Analysis of Published Epidemiological Studies

We performed a meta-analysis to analyze the association of various levels of green tea consumption with risk of esophageal cancer. We searched MEDLINE, EMBASE, and the Cochrane Library for studies of green tea consumption and esophageal cancer and identified 12 observational studies. For esophageal cancer, the pooled relative risk (RR) was 1.09 [95% confidence interval (CI), 0.76–1.55] for greatest vs. non/least green tea consumption; however, there was significant heterogeneity across studies (P = 0.00, I² = 75.5%). Compared with subjects who drank no/least green tea, the pooled RR was 1.14 (95% CI = 0.97–1.35) for moderate drinkers, 0.94 (95% CI = 0.77–1.13) for those who drank little, and 0.97 (95% CI = 0.77–1.22) for all subjects who had ever drunk green tea. Subgroup analysis showed that the RR was 0.46 (95% CI = 0.29–0.73) for female subjects. The results of the present meta-analysis are that any association between green tea and risk of esophageal cancer remains unclear. Subgroup analyses indicated that greater consumption of green tea might reduce the risk of esophageal cancer in female subjects. However, the results are based on limited research. Further research is needed to confirm the results and clarify the likely biological mechanisms.     

Tea consumption may decrease the risk of osteoporosis: an updated meta-analysis of observational studies

Several epidemiological investigations have evaluated the correlation between tea consumption and risk of osteoporosis, but the results are inconsistent. Therefore, we conducted an updated meta-analysis of observational studies to assess this association. We searched for all relevant studies including cohort, cross-sectional, and case-control studies published from database inception to July 15, 2016, using MEDLINE EMBASE, and Cochrane Library. Polled odds ratios (ORs) were calculated using the random-effect model. Fourteen articles (16 studies) that examined 138 523 patients were included in this meta-analysis. Seven studies concerning bone mineral density (BMD) showed an increase in BMD with tea consumption, including 4 cross-sectional studies (OR, 0.04, 95% confidence interval [CI], 0.01-0.08) and 3 cohort studies (OR, 0.01; 95% CI, 0.01-0.01). The remaining 9 studies concerning fracture, including 6 case-control studies and 3 cohort studies, showed no association between tea consumption and osteoporotic fracture (OR, 0.86; 95% CI, 0.74-1.01). This updated meta-analysis demonstrates that tea consumption could increase BMD, but the association with osteoporotic fracture requires further investigation. Together, the results highlight the need for future, high-quality–designed clinical trials on tea consumption and osteoporosis.     

Milk consumption and bladder cancer risk: a meta-analysis of published epidemiological studies

Studies investigating the association of milk consumption with bladder cancer risk have reported inconsistent findings. We conducted a meta-analysis of published cohort and case-control studies to pool the risk estimates of the association between milk intake and bladder cancer. We quantified associations with bladder cancer using meta-analysis of odds ratio (OR) associated with the highest vs. the lowest category of milk intake using fixed- or random-effect models depending on the heterogeneity of effects among studies. Nineteen cohort and case-control studies were eligible for inclusion. High milk intake was significantly associated with decreased risk of bladder cancer (OR, 0.84; 95% CI, 0.71-0.97) when comparing the highest with the lowest category of milk intake. The inverse association was stronger in Asia (OR, 0.60; 95% CI, 0.40-0.81) than North America (OR, 0.89; 95% CI, 0.76-1.03), and no association was observed in Europe (OR, 1.05; 95% CI, 0.85-1.26). This relationship also varied significantly by specific dairy products. Our results suggest that milk may be related to the reduction of bladder cancer risk. Further studies need to clarify the biological mechanisms.     

Coffee and gastric cancer: systematic review and meta-analysis

We systematically reviewed the literature on the association between coffee consumption and gastric cancer and performed a meta-analysis of the results. Published cohort and case-control studies were identified in PubMed and reference lists. Random effects meta-analysis was used to pool effects from 23 studies, and heterogeneity was explored by stratification and meta-regression. The odds ratio (OR) for the overall association between coffee and gastric cancer (highest vs. lowest category of exposure) was 0.97 (95%CI: 0.86-1.09), similar for cohort (OR = 1.02; 95%CI: 0.76-1.37) and case-control studies (population-based: OR = 0.90; 95%CI: 0.70-1.15; hospital-based: OR = 0.97; 95%CI: 0.83-1.13). The OR was 1.26 (95%CI: 1.02-1.57) when considering five studies conducted in the USA, 0.97 (95%CI: 0.82-1.14) for the five Japanese studies, 0.98 (95%CI: 0.81-1.17) for the six studies from Europe, and 0.64 (95%CI: 0.47-0.86) for the two studies from South America. In this meta-analysis we found no adverse effect of coffee associated with gastric cancer. Knowledge on the level of exposure to different coffee constituents may provide a deeper understanding of this reassuring result and the real role of coffee on cancer risk.     

Green tea consumption and chronic atrophic gastritis: a cross-sectional study in a green tea production village

Chronic atrophic gastritis (CAG) is well known as a precancerous lesion of the stomach, and Helicobacter pylori (H. pylori) infection increases the risk of CAG. While recent studies have reported that green tea consumption decreases the risk of gastric cancer, there has been no study analyzing the relationship between green tea consumption and the both risks H. pylori infection and CAG. We conducted a cross-sectional study on 636 subjects living in a farming village in Japan to examine the relationship among green tea consumption, H. pylori infection, and CAG. Smoking, alcohol drinking, consumption of four beverages, including green tea, and of five foods were investigated as lifestyle factors that may affect H. pylori infection and CAG. The measurement of H. pylori-IgG antibodies was used to define H. pylori infection, and serum pepsinogens were used to define of CAG. The unconditional logistic regression model was used for analyzing each odds ratio (OR). H. pylori infection was positively associated with the risk of CAG (OR = 3.73; 95% confidence interval [CI], 2.59-5.36). High green tea consumption (more than 10 cups per day) was negatively associated with the risk of CAG, even after adjustment for H. pylori infection and lifestyle factors associated with green tea consumption (OR = 0.63; 95% CI, 0.43-0.93). These results support the hypothesis that high green tea consumption prevents CAG.     

Green Tea and Incidence of Colorectal Cancer: Evidence from Prospective Cohort Studies

A systematic meta-analysis of prospective cohort studies on green tea consumption and colorectal cancer was performed to determine whether green tea has a chemopreventive effect against colorectal cancer. Six eligible cohort studies involving 352,275 participants and 1675 cases of colorectal cancer were identified. Combined relative risk (RR) ratios for the highest vs. lowest and increment of 1 cup/day green tea consumption levels were calculated. The combined RR of 0.90 (95% CI: 0.72–1.08) was found comparing highest vs. lowest green tea consumption levels for colorectal cancer. No significant differences by cancer-site were found, but an inverse association between green tea and incidence of colorectal cancer (RR: 0.70; 95% CI: 0.55–0.85) and colon cancer (RR: 0.69; 95% CI: 0.48–0.98) was demonstrated in Shanghai population. Singapore men had a higher risk of colorectal cancer (RR: 1.36; 95% CI: 1.06–1.74). Furthermore, an increase in green tea consumption of 1 cup/day was not associated with incidence of colorectal cancer (RR: 0.97; 95% CI: 0.91–1.03). Despite the limited evidence from Shanghai studies in support of green tea as potential chemopreventive agents against colorectal cancer, available data from prospective cohort studies are insufficient to conclude that green tea may protect against colorectal cancer.     

Coffee Drinking and the Risk of Endometrial Cancer: An Updated Meta-Analysis of Observational Studies

Background: Several compounds contained in coffee have been found to suppress carcinogenesis in experimental studies. We conducted a dose–response meta-analysis to assess the impact of coffee consumption on the risk of endometrial cancer. Materials and methods: We searched MEDLINE and EMBASE databases for studies published up to August 2016. Using random effects models, we estimated summary relative risks (RR) for cohort studies and odds ratios (OR) for case-control studies with 95% confidence intervals (CI). Dose–response analyses were conducted by using generalized least square trend estimation. Results: We identified 12 cohort studies and 8 case-control studies eligible for inclusion, contributing with 11,663 and 2,746 endometrial cancer cases, respectively. The summary RR for highest compared with lowest coffee intake was 0.74 (95% CI: 0.68–0.81; p_{heterogeneity} = 0.09, I² = 32%). The corresponding summary RR among cohort studies was 0.78 (95% CI: 0.71–0.85; p_{heterogeneity} = 0.14, I² = 31.9%) and 0.63 (95% CI: 0.53–0.76; p_{heterogeneity} = 0.57, I² = 0%) for case-control studies. One-cup increment per day was associated with 3% risk reduction (95% CI: 2–4%) in cohort studies and 12% (95% CI: 5–18%) in case-control studies. After pooling the results from 5 cohort studies, the association remained significant only in women with body mass index over 30 (RR = 0.71, 95% CI: 0.61–0.81). Conclusion: The results from our meta-analysis strengthen the evidence of a protective effect of coffee consumption on the risk of EC and further suggest that increased coffee intake might be particularly beneficial for women with obesity.     

Milk Consumption and Bladder Cancer Risk: A Meta-Analysis of Published Epidemiological Studies

Studies investigating the association of milk consumption with bladder cancer risk have reported inconsistent findings. We conducted a meta-analysis of published cohort and case-control studies to pool the risk estimates of the association between milk intake and bladder cancer. We quantified associations with bladder cancer using meta-analysis of odds ratio (OR) associated with the highest vs. the lowest category of milk intake using fixed- or random-effect models depending on the heterogeneity of effects among studies. Nineteen cohort and case-control studies were eligible for inclusion. High milk intake was significantly associated with decreased risk of bladder cancer (OR, 0.84; 95% CI, 0.71–0.97) when comparing the highest with the lowest category of milk intake. The inverse association was stronger in Asia (OR, 0.60; 95% CI, 0.40–0.81) than North America (OR, 0.89; 95% CI, 0.76–1.03), and no association was observed in Europe (OR, 1.05; 95% CI, 0.85–1.26). This relationship also varied significantly by specific dairy products. Our results suggest that milk may be related to the reduction of bladder cancer risk. Further studies need to clarify the biological mechanisms.     

Parkinson's disease risks associated with cigarette smoking, alcohol consumption, and caffeine intake

A reduced risk for Parkinson's disease (PD) among cigarette smokers has been observed consistently during the past 30 years. Recent evidence suggests that caffeine may also be protective. Findings are presented regarding associations of PD with smoking, caffeine intake, and alcohol consumption from a case-control study conducted in western Washington State in 1992-2000. Incident PD cases (n = 210) and controls (n = 347), frequency matched on gender and age were identified from enrollees of the Group Health Cooperative health maintenance organization. Exposure data were obtained by in-person questionnaires. Ever having smoked cigarettes was associated with a reduced risk of PD (odds ratio (OR) = 0.5, 95% confidence interval (CI): 0.4, 0.8). A stronger relation was found among current smokers (OR = 0.3, 95% CI: 0.1, 0.7) than among ex-smokers (OR = 0.6, 95% CI: 0.4, 0.9), and there was an inverse gradient with pack-years smoked (trend p < 0.001). No associations were detected for coffee consumption or total caffeine intake or for alcohol consumption. However, reduced risks were observed for consumption of 2 cups/day or more of tea (OR = 0.4, 95% CI: 0.2, 0.9) and two or more cola drinks/day (OR = 0.6, 95% CI: 0.3, 1.4). The associations for tea and cola drinks were not confounded by smoking or coffee consumption.