Zheng W, Doyle T J, Kushi L H, Sellers T A, Hong C P, Folsom A R
Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis 55454, USA.
Am J Epidemiol. 1996 Jul 15;144(2):175-82. doi: 10.1093/oxfordjournals.aje.a008905.
Tea has consistently been shown to inhibit the occurrence of tumors in experimental animals. The evidence for such a beneficial effect in humans, however, is limited. The authors examined the association between non-herbal tea consumption and cancer incidence in a prospective cohort study of 35,369 postmenopausal Iowa women. In this cohort, information on the frequency of tea drinking and other dietary and lifestyle factors was collected by mailed survey in 1986. After 8 years of follow-up, 2,936 incident non-skin cancer cases were ascertained in this cohort through the State Health Registry of Iowa. Proportional hazards regressions were used to derive adjusted relative risks and 95% confidence intervals for the association between tea consumption and cancer incidence. After controlling for confounding factors, the authors found that regular tea consumption was related to a slight, but not statistically significant, reduced incidence of all cancers combined. Inverse associations with increasing frequency of tea drinking were seen for cancers of the digestive tract (p for trend, 0.04) and the urinary tract (p for trend, 0.02). For women who reported drinking > or = 2 cups (474 ml) of tea per day, compared with those who never or occasionally drank tea, the relative risk for digestive tract cancers was 0.68 (95% confidence interval (CI) 0.47-0.98) and for urinary tract cancers, 0.40 (95% CI 0.16-0.98). Similar inverse associations were seen for specific digestive and urinary tract cancers, although site-specific analyses were not statistically significant. No appreciable association of tea drinking was found with melanoma, non-Hodgkin's lymphoma, or cancers of the pancreas, lung, breast, uterine corpus, or ovary. This study suggests that tea, one of the most popular beverages consumed worldwide, may protect against some cancers in postmenopausal women.
研究表明，茶能够抑制实验动物体内肿瘤的发生。然而，茶对人体产生这种有益作用的证据却很有限。作者在一项针对35369名爱荷华州绝经后女性的前瞻性队列研究中，检验了饮用非花草茶与癌症发病率之间的关联。在这个队列中，通过1986年邮寄调查收集了饮茶频率以及其他饮食和生活方式因素的信息。经过8年的随访，通过爱荷华州州立健康登记处确定了该队列中有2936例新发非皮肤癌病例。采用比例风险回归分析得出饮茶与癌症发病率之间关联的调整后相对风险及95%置信区间。在控制了混杂因素后，作者发现经常饮茶与所有癌症合并发病率略有降低相关，但在统计学上无显著意义。对于消化道癌症（趋势p值为0.04）和泌尿系统癌症（趋势p值为0.02），随着饮茶频率增加呈现负相关。对于报告每天饮用≥2杯（474毫升）茶的女性，与从不或偶尔饮茶的女性相比，消化道癌症的相对风险为0.68（95%置信区间（CI）0.47 - 0.98），泌尿系统癌症的相对风险为0.40（95% CI 0.16 - 0.98）。对于特定的消化道和泌尿系统癌症也观察到类似的负相关，尽管按部位分析在统计学上无显著意义。未发现饮茶与黑色素瘤、非霍奇金淋巴瘤或胰腺癌、肺癌、乳腺癌、子宫体癌或卵巢癌有明显关联。这项研究表明，茶作为全球最受欢迎的饮品之一，可能对绝经后女性的某些癌症具有预防作用。
