JAMA Intern.Med：补钙提高男性心血管疾病死亡率

西方国家老年人普遍通过补钙来预防骨质疏松症，然而，过量的钙补充对心脏和血管等非骨骼系统器官的影响仍不清楚。美国国立癌症研究所Qian Xiao博士及其同事研究发现，高钙摄入（>1,000 mg/日）与男性心血管疾病（CVD）风险升高有关，而女性中无此关联。研究结果在2013年2月4日在线发表于《美国医学杂志-内科学》。
这项前瞻性队列研究招募了50-71周岁的219,059名男性和169,170名女性，平均随访12年，以分析补钙对CVD死亡率的影响。研究发现，男性心血管死亡风险有显著提高（相对风险 [RR] 1.20, 95% CI 1.05–1.36, P <0.001），且主要归因于心脏病风险的提高（RR 1.19, 95% CI 1.03–1.37, P = 0.001）。亚组分析发现，仅吸烟者中存在的不良反应与膳食钙摄入无关。分析还发现，补钙没有提高女性的CVD死亡率。此外，研究未对维生素D摄入量、家族心脏病史及钙补充持续时间等混杂因素进行分析。
该研究结果既与“补钙可保护心血管”的假设相悖，也与妇女健康倡议等提出“补钙会提高女性CVD风险”的多项早期研究不一致。现有的假设提示，补钙的净效果可能取决于实际摄入的钙量、钙水平的骤变或其他协同的风险因子。目前关于补钙整体效应的数据结果并不确定，仍需深入研究。唯一确定的是，补钙有益于骨骼健康，膳食补钙是一条安全的途径。

 与心血管疾病相关的拓展阅读：

• Diabetes Care: 低血糖和空腹血糖受损均可预测心血管疾病发病风险
• 面相老的人患心血管疾病风险高
• 综述：盘点2012年心血管疾病预防新进展
• FDA警告 伐尼克兰或有致心血管疾病风险
• JAMA：每日补充多种维生素未能降低心血管疾病风险
• 中文版2012ESC心血管疾病预防指南
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Dietary and Supplemental Calcium Intake and Cardiovascular Disease Mortality:
 The National Institutes of Health–AARP Diet and Health Study
Importance 
Calcium intake has been promoted because of its proposed benefit on bone health, particularly among the older population. However, concerns have been raised about the potential adverse effect of high calcium intake on cardiovascular health.
Objective 
To investigate whether intake of dietary and supplemental calcium is associated with mortality from total cardiovascular disease (CVD), heart disease, and cerebrovascular diseases.
Design and Setting
Prospective study from 1995 through 1996 in California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania and the 2 metropolitan areas of Atlanta, Georgia, and Detroit, Michigan.
Participants
A total of 388 229 men and women aged 50 to 71 years from the National Institutes of Health–AARP Diet and Health Study.
Main Outcome Measures
Dietary and supplemental calcium intake was assessed at baseline (1995-1996). Supplemental calcium intake included calcium from multivitamins and individual calcium supplements. Cardiovascular disease deaths were ascertained using the National Death Index. Multivariate Cox proportional hazards regression models adjusted for demographic, lifestyle, and dietary variables were used to estimate relative risks (RRs) and 95% CIs.
Results
During a mean of 12 years of follow-up, 7904 and 3874 CVD deaths in men and women, respectively, were identified. Supplements containing calcium were used by 51% of men and 70% of women. In men, supplemental calcium intake was associated with an elevated risk of CVD death (RR>1000 vs 0 mg/d, 1.20; 95% CI, 1.05-1.36), more specifically with heart disease death (RR, 1.19; 95% CI, 1.03-1.37) but not significantly with cerebrovascular disease death (RR, 1.14; 95% CI, 0.81-1.61). In women, supplemental calcium intake was not associated with CVD death (RR, 1.06; 95% CI, 0.96-1.18), heart disease death (1.05; 0.93-1.18), or cerebrovascular disease death (1.08; 0.87-1.33). Dietary calcium intake was unrelated to CVD death in either men or women.
Conclusions and Relevance
Our findings suggest that high intake of supplemental calcium is associated with an excess risk of CVD death in men but not in women. Additional studies are needed to investigate the effect of supplemental calcium use beyond bone health.