补钙可能增加老年女性心脏病发作的风险
Vascular events in healthy older women receiving calcium supplementation: randomised controlled trialObjective : To determine the effect of calcium supplementation on myocardial infarction, stroke, and sudden death in healthy postmenopausal women.
Design Randomised, placebo controlled trial.
Setting Academic medical centre in an urban setting in New Zealand.
Participants 1471 postmenopausal women (mean age 74): 732 were randomised to calcium supplementation and 739 to placebo.
Main outcome measures: Adverse cardiovascular events over five years: death, sudden death, myocardial infarction, angina, other chest pain, stroke, transient ischaemic attack, and a composite end point of myocardial infarction, stroke, or sudden death.
Results: Myocardial infarction was more commonly reported in the calcium group than in the placebo group (45 events in 31 women v 19 events in 14 women, P=0.01). The composite end point of myocardial infarction, stroke, or sudden death was also more common in the calcium group (101 events in 69 women v 54 events in 42 women, P=0.008). After adjudication myocardial infarction remained more common in the calcium group (24 events in 21 women v 10 events in 10 women, relative risk 2.12, 95% confidence interval 1.01 to 4.47). For the composite end point 61 events were verified in 51 women in the calcium group and 36 events in 35 women in the placebo group (relative risk 1.47, 0.97 to 2.23). When unreported events were added from the national database of hospital admissions in New Zealand the relative risk of myocardial infarction was 1.49 (0.86 to 2.57) and that of the composite end point was 1.21 (0.84 to 1.74). The respective rate ratios were 1.67 (95% confidence intervals 0.98 to 2.87) and 1.43 (1.01 to 2.04); event rates: placebo 16.3/1000 person years, calcium 23.3/1000 person years. For stroke (including unreported events) the relative risk was 1.37 (0.83 to 2.28) and the rate ratio was 1.45 (0.88 to 2.49).
Conclusion : Calcium supplementation in healthy postmenopausal women is associated with upward trends in cardiovascular event rates. This potentially detrimental effect should be balanced against the likely benefits of calcium on bone.
绝经后的女性通常通过补钙来保持骨骼健康，一些医生也认为钙能通过降低胆固醇水平来预防血栓。然而最近新西兰奥克兰大学一项研究显示，补钙可能会使健康绝经后女性心脏病发作风险增加。
文章发表在1月16日出版的BMJ上。这项研究最早是为了考察补钙对骨折的影响。共有1471位超过55岁的绝经后女性参加了这项随机、安慰剂对照试验，受试者平均年龄为74岁。补钙组每天补充约1861mg钙，对照组仅每天从饮食中吸收约853mg钙。受试者每6月评估一次，观察期为5年。主要评价指标为以下几项心血管相关事件：死亡、猝死、心绞痛、心肌梗死、胸痛、中风、短暂性脑缺血发作等。
结果显示，与安慰剂组相比，补钙组心肌梗死发生率显著增加；心血管事件（心肌梗死、中风及猝死）发生率也显著增加。
研究者认为，健康绝经后女性补钙与心血管事件增加趋势相关，然而他们同时谨慎地补充“补钙潜在的有害作用可能与它对骨骼的有益作用相平衡。”
原文链接：[url]http://www.bmj.com/cgi/content/full/bmj.39440.525752.BEv1[/url]
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