英国格拉斯哥大学的一项新的研究警告称，喝茶过量的男性患前列腺癌的风险较大。那些每天喝7杯以上茶的男性，患前列腺癌的几率要比喝3杯以下的男性高近50%。
研究人员对6000多名男性的健康状况进行了长达近40年的跟踪调查，其研究结果却和先前的研究截然不同。
先前的研究指出，喝茶不仅能降低患癌症的风险，还能减少患心脏病、糖尿病和帕金森氏症的风险。
这项研究于1970年开始，受试者的年龄介于21岁到75岁之间，他们被要求填写问卷，内容包括平常喝茶、咖啡和酒的分量，吸烟习惯，以及整体健康状况，受试者还需参加筛检。
在6016名男性受试者中，仅有不到1/4的人喝茶过量，每天要喝7杯茶。而这些过量喝茶者，其中有6.4%的人在接下来37年里患了前列腺癌。
发表在最近出版的《营养与癌症》（Nutrition and Cancer）期刊上的该研究称，先前的研究大多显示，红茶和前列腺癌并无关联，或绿茶有些预防效果。
目前还不清楚到底茶本身是危险因子，还是喝茶的人正好是前列腺癌的好发年龄。不过，研究人员称，喝茶最多的受试者不太可能会体重过重或是有饮酒习惯，且较可能有健康的胆固醇值。
研究人员指出，由于该研究只考虑到受试者饮用茶、咖啡和酒精的量，没有考虑到家族病史及其他饮食情况，因此不希望任何人误认为，适量饮茶也会增加患前列腺癌的风险。（生物谷Bioon.com）
doi:10.1080/01635581.2012.690063
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Tea Consumption and the Risk of Overall and Grade Specific Prostate Cancer: A Large Prospective Cohort Study of Scottish Men
Kashif Shafiquea, Philip McLooneb, Khaver Qureshic, Hing Leungd, Carole Harta & David S. Morrisonb
Tea may be a potentially modifiable and highly prevalent risk factor for the most common cancer in men, prostate cancer. However, associations between black tea consumption and prostate cancer in epidemiological studies have been inconsistent, limited to a small number of studies with small numbers of cases and short follow-up periods and without grade-specific information. We conducted a prospective cohort study of 6,016 men who were enrolled in the Collaborative Cohort Study between 1970 and 1973 and followed up to December 31, 2007. We used Cox proportional hazards models to investigate the association between tea consumption and overall as well as grade-specific risk of prostate cancer incidence. Three hundred and eighteen men developed prostate cancer in up to 37 years of follow-up. We found a positive association between consumption of tea and overall risk of prostate cancer incidence (P = 0.02). The association was greatest among men who drank ≥7 cups of tea per day (HR: 1.50, 95% CI: 1.06 to 2.12), compared with the baseline of 0–3 cups/day. However, we did not find any significant association between tea intake and low- (Gleason <7) or high-grade (Gleason 8–10) prostate cancer incidence. Men with higher intake of tea are at greater risk of developing prostate cancer, but there is no association with more aggressive disease. Further research is needed to determine the underlying biological mechanisms for the association.
