Michaëlsson Karl, Wolk Alicja, Langenskiöld Sophie, Basu Samar, Warensjö Lemming Eva, Melhus Håkan, Byberg Liisa
Department of Surgical Sciences, Uppsala University, SE-751 85 Uppsala, Sweden
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
BMJ. 2014 Oct 28;349:g6015. doi: 10.1136/bmj.g6015.
To examine whether high milk consumption is associated with mortality and fractures in women and men.
Cohort studies.
Three counties in central Sweden.
Two large Swedish cohorts, one with 61,433 women (39-74 years at baseline 1987-90) and one with 45,339 men (45-79 years at baseline 1997), were administered food frequency questionnaires. The women responded to a second food frequency questionnaire in 1997.
Multivariable survival models were applied to determine the association between milk consumption and time to mortality or fracture.
During a mean follow-up of 20.1 years, 15,541 women died and 17,252 had a fracture, of whom 4259 had a hip fracture. In the male cohort with a mean follow-up of 11.2 years, 10,112 men died and 5066 had a fracture, with 1166 hip fracture cases. In women the adjusted mortality hazard ratio for three or more glasses of milk a day compared with less than one glass a day was 1.93 (95% confidence interval 1.80 to 2.06). For every glass of milk, the adjusted hazard ratio of all cause mortality was 1.15 (1.13 to 1.17) in women and 1.03 (1.01 to 1.04) in men. For every glass of milk in women no reduction was observed in fracture risk with higher milk consumption for any fracture (1.02, 1.00 to 1.04) or for hip fracture (1.09, 1.05 to 1.13). The corresponding adjusted hazard ratios in men were 1.01 (0.99 to 1.03) and 1.03 (0.99 to 1.07). In subsamples of two additional cohorts, one in males and one in females, a positive association was seen between milk intake and both urine 8-iso-PGF2α (a biomarker of oxidative stress) and serum interleukin 6 (a main inflammatory biomarker).
High milk intake was associated with higher mortality in one cohort of women and in another cohort of men, and with higher fracture incidence in women. Given the observational study designs with the inherent possibility of residual confounding and reverse causation phenomena, a cautious interpretation of the results is recommended.
研究高牛奶摄入量与女性及男性死亡率和骨折之间是否存在关联。
队列研究。
瑞典中部的三个县。
两个瑞典大型队列，一个队列有61433名女性（1987 - 1990年基线时年龄为39 - 74岁），另一个队列有45339名男性（1997年基线时年龄为45 - 79岁），均接受了食物频率问卷调查。这些女性在1997年又回复了一份食物频率问卷。
应用多变量生存模型来确定牛奶摄入量与死亡或骨折时间之间的关联。
在平均20.1年的随访期间，15541名女性死亡，17252名女性发生骨折，其中4259名发生髋部骨折。在平均随访11.2年的男性队列中，10112名男性死亡，5066名男性发生骨折，其中1166例为髋部骨折。在女性中，每天饮用三杯或更多杯牛奶与每天饮用少于一杯牛奶相比，调整后的死亡风险比为1.93（95%置信区间为1.80至2.06）。对于女性，每多喝一杯牛奶，全因死亡的调整后风险比为1.15（1.13至1.17），男性为1.03（1.01至1.04）。对于女性，无论何种骨折（1.02，1.00至1.04）或髋部骨折（1.09，1.05至1.13），随着牛奶摄入量增加，骨折风险均未降低。男性相应的调整后风险比分别为1.01（0.99至1.03）和1.03（0.99至1.07）。在另外两个队列的亚样本中，一个为男性队列，一个为女性队列，牛奶摄入量与尿液8 - 异前列腺素F2α（氧化应激生物标志物）和血清白细胞介素6（主要炎症生物标志物）之间均呈正相关。
在一组女性队列和另一组男性队列中，高牛奶摄入量与较高死亡率相关，在女性中还与较高骨折发生率相关。鉴于观察性研究设计存在残留混杂和反向因果关系现象的内在可能性，建议对结果进行谨慎解读。
