Center for Nutrition, Healthy Lifestyle, and Disease Prevention, School of Public Health, Loma Linda University, Loma Linda, CA, USA.
Int J Epidemiol. 2020 Oct 1;49(5):1526-1537. doi: 10.1093/ije/dyaa007.
Associations between soy, dairy intakes and breast cancer risk are inconsistent. No studies exist with large numbers of dairy consumers and soy consumers to assess mutual confounding.
The study cohort contains 52 795 North American women, initially free of cancer, followed for 7.9 years (29.7% were Black). Dietary intakes were estimated from food frequency questionnaires and, for 1011 calibration study subjects, from six structured 24-h dietary recalls. Incident invasive breast cancers were detected mainly by matching with cancer registries. Analyses used multivariable proportional hazards regression.
The participants (mean age of 57.1 years) experienced 1057 new breast cancer cases during follow-up. No clear associations were found between soy products and breast cancer, independently of dairy. However, higher intakes of dairy calories and dairy milk were associated with hazard ratios (HRs) of 1.22 [95% confidence interval (CI): 1.05-1.40] and 1.50 (95% CI 1.22-1.84), respectively, comparing 90th to 10th percentiles of intakes. Full fat and reduced fat milks produced similar results. No important associations were noted with cheese and yogurt. Substituting median intakes of dairy milk users by those of soy milk consumers was associated with HR of 0.68 (95% CI: 0.55-0.85). Similar-sized associations were found among pre- and post-menopausal cases, with CIs also excluding the null in estrogen receptor (ER+, ER-), and progesterone receptor (PR+) cancers. Less biased calibrated measurement-error adjusted regressions demonstrated yet stronger, but less precise, HRs and CIs that still excluded the null.
Higher intakes of dairy milk were associated with greater risk of breast cancer, when adjusted for soy intake. Current guidelines for dairy milk consumption could be viewed with some caution.
大豆和乳制品的摄入与乳腺癌风险之间的关联并不一致。目前尚无研究针对大量的乳制品消费者和大豆消费者进行评估，以了解它们之间的相互混杂作用。
研究队列包含 52795 名北美女性，最初无癌症，随访 7.9 年（29.7%为黑人）。膳食摄入量通过食物频率问卷进行评估，对于 1011 名校准研究对象，通过 6 次结构化 24 小时膳食回忆进行评估。通过与癌症登记处的匹配，主要检测出浸润性乳腺癌新发病例。分析采用多变量比例风险回归。
参与者（平均年龄为 57.1 岁）在随访期间经历了 1057 例新发乳腺癌。在独立于乳制品的情况下，大豆制品与乳腺癌之间未发现明确的关联。然而，较高的乳制品热量和牛奶摄入量与危险比（HR）分别为 1.22（95%置信区间（CI）：1.05-1.40）和 1.50（95%CI 1.22-1.84），比较摄入量的第 90 百分位与第 10 百分位。全脂和低脂牛奶产生了类似的结果。与奶酪和酸奶无重要关联。用豆奶消费者的中位数摄入量替代牛奶使用者的中位数摄入量，与 HR 为 0.68（95%CI：0.55-0.85）相关。在绝经前和绝经后病例中也发现了类似大小的关联，CI 也排除了雌激素受体（ER+、ER-）和孕激素受体（PR+）癌症的零假设。经过更偏向于校准测量误差调整的回归分析，得出了更强但不太精确的 HR 和 CI，仍然排除了零假设。
在调整大豆摄入量后，摄入更多的牛奶与乳腺癌风险增加相关。目前对牛奶消费的指南可能需要谨慎看待。
