咖啡、茶、咖啡因能否减少乳腺癌
关于咖啡、茶摄入量对绝经前和绝经后女性乳腺癌发病率的影响，既往研究结果互相矛盾。
2021年7月27日，英国剑桥大学出版社《公共卫生营养》在线发表中国沈阳药科大学、辽宁中医药大学附属医院的研究报告，对咖啡和/或茶摄入量与绝经前和绝经后女性乳腺癌风险的相关性进行了系统回顾和网状荟萃分析。
该研究首先对美国国家医学图书馆、荷兰医学文摘、考科蓝图书馆过去30年收录的文献进行系统回顾，筛选出评估咖啡和茶摄入量对乳腺癌影响的45项病例对照研究或前瞻定群研究，其中包括超过332万3288例参与者符合分析条件。
随后进行网状荟萃分析，确定咖啡和/或茶摄入量对乳腺癌风险的影响，根据亚组分析和荟萃回归分析咖啡/茶类型、绝经状态、激素受体和体重指数的差异。
根据成对荟萃分析，咖啡摄入量较少和茶摄入量较多可能对预防雌激素受体阴性乳腺癌有效，尤其对于绝经后女性。
根据成对荟萃分析和网状荟萃分析，确定推荐每天2～3杯咖啡或≥5杯茶，其中含有高浓度咖啡因，尤其对于绝经后女性。
因此，该研究结果表明，咖啡和茶的摄入量与绝经后女性总体乳腺癌风险无关，与雌激素受体阴性乳腺癌风险可能相关，推荐每天最高2～3杯咖啡或≥5杯茶。
不过，对于杯的具体容量，各国有所不同。在美国，传统1杯通常为8美制盎司约237毫升，法定1杯通常为240毫升；在英国，标准1杯为10英制盎司约284毫升；在加拿大，传统1杯为8英制盎司约227毫升，标准1杯为250毫升；在澳大利亚和新西兰等英联邦国家，咖啡1杯为150毫升，标准1杯为250毫升；在拉丁美洲，1杯为200毫升或250毫升；在日本，传统1杯约180毫升，现代1杯为200毫升。
Public Health Nutr. 2021 Jul 27. Online ahead of print.
Does coffee, tea and caffeine consumption reduce the risk of incident breast cancer? A systematic review and network meta-analysis.
Wang S, Li X, Yang Y, Xie J, Liu M, Zhang Y, Zhang Y, Zhao Q.
Shenyang Pharmaceutical University, Shenyang, China; Affiliated Hospital of Liaoning University of Traditional Chinese Medicine, Shenyang, China.
OBJECTIVE: We aimed to evaluate the association between coffee and/or tea consumption and breast cancer (BC) risk among premenopausal and postmenopausal women and to conduct a network meta-analysis.
DESIGN: Systematic review and network meta-analysis.
SETTING: We conducted a systematic review of electronic publications in the last 30 years to identify case-control studies or prospective cohort studies that evaluated the effects of coffee and tea intake.
RESULTS: Forty-five studies that included more than 3 323 288 participants were eligible for analysis. Network meta-analysis was performed to determine the effects of coffee and/or tea consumption on reducing BC risk in a dose-dependent manner and differences in coffee/tea type, menopause status, hormone receptor and the BMI in subgroup and meta-regression analyses. According to the first pairwise meta-analysis, low-dose coffee intake and high-dose tea intake may exhibit efficacy in preventing ER(estrogen receptor)- BC, particularly in postmenopausal women. Then, we performed another pairwise and network meta-analysis and determined that the recommended daily doses were 2-3 cups/d of coffee or ≥5 cups/d of tea, which contained a high concentration of caffeine, particularly in postmenopausal women.
CONCLUSIONS: Coffee and tea consumption is not associated with a reduction in the overall BC risk in postmenopausal women and is associated with a potentially lower risk of ER- BC. And the highest recommended dose is 2-3 cups of coffee/d or ≥5 cups of tea/d. They are potentially useful dietary protectants for preventing BC.
KEYWORDS: Breast cancer; Coffee; Network meta-analysis; Preventing; Tea
PMID: 34311801
DOI: 10.1017/S1368980021000720