Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
JNCI Cancer Spectr. 2021 Apr 12;5(3). doi: 10.1093/jncics/pkab032. eCollection 2021 Jun.
Branched chain amino acids (BCAAs) are essential amino acids common throughout the US diet. Although circulating BCAAs have been implicated in insulin resistance and some obesity-related cancers, the relationship between dietary intake of BCAAs and incident breast cancer is unknown. We sought to evaluate the association between long-term dietary intakes of BCAAs and invasive breast cancer risk.
Our analyses included 196 161 women from the Nurses' Health Study and Nurses' Health Study II longitudinal cohorts. Average intakes of total and individual BCAAs (isoleucine, leucine, valine) were estimated from repeated diet questionnaires and incident self-reported breast cancer cases were confirmed via medical record review. Cox proportional hazards models, adjusted for reproductive history, lifestyle, body mass index, and other breast cancer risk factors, were used to estimate hazard ratios and 95% confidence intervals.
We observed 10 046 incident cases of breast cancer over a median of 20.8 years of follow-up. No associations between dietary intakes of total or individual BCAAs with breast cancer risk were observed. Compared with women in the bottom quintile of BCAA intake, the hazard ratio of breast cancer for those in the top quintile was 1.05 (95% confidence interval = 0.98 to 1.12; 2-sided = .20). Findings were consistent across molecular subtypes and according to type 2 diabetes diagnosis and body mass index categories.
Dietary intakes of BCAAs are not likely a risk factor for breast cancer.
支链氨基酸（BCAAs）是美国饮食中常见的必需氨基酸。尽管循环中的 BCAAs 与胰岛素抵抗和一些与肥胖相关的癌症有关，但饮食中 BCAAs 的摄入量与乳腺癌的发生之间的关系尚不清楚。我们试图评估长期饮食中 BCAAs 的摄入量与浸润性乳腺癌风险之间的关系。
我们的分析包括来自护士健康研究和护士健康研究 II 纵向队列的 196161 名女性。通过重复的饮食问卷评估总 BCAAs 和个体 BCAAs（异亮氨酸、亮氨酸、缬氨酸）的平均摄入量，通过医疗记录审查确认新发生的自我报告乳腺癌病例。使用 Cox 比例风险模型，调整生育史、生活方式、体重指数和其他乳腺癌危险因素，估计风险比和 95%置信区间。
在中位数为 20.8 年的随访中，我们观察到 10046 例乳腺癌新发病例。饮食总 BCAAs 或个体 BCAAs 摄入量与乳腺癌风险之间没有关联。与 BCAAs 摄入量处于最低五分位数的女性相比，摄入量处于最高五分位数的女性患乳腺癌的风险比为 1.05（95%置信区间为 0.98 至 1.12；双侧 P =.20）。研究结果在分子亚型之间以及根据 2 型糖尿病诊断和体重指数类别均一致。
饮食中 BCAAs 的摄入量不太可能是乳腺癌的一个危险因素。
