Erin Michos  美国霍普金斯Ciccarone心脏病预防中心

　　<International Circulation>: There has been a correlation established between vitamin D and cardiovascular disease. Could you explain some of the mechanisms by which this happens?

　　《国际循环》：已经有证据表明维生素D和心血管疾病之间有相关性。您能解释下他们之间的这种相关性的机制吗？

　　Dr Michos: Even though there is a minor link between low vitamin D and cardiovascular events like heart attack， stroke and death， it is still only observational data. There may be some problems with residual confounding such that people who have a poor health status and are less likely to get outdoor physical activity and that may be why they have these worse outcomes. That being said， there is some compelling biological basis for why there is a true relationship between vitamin D and cardiovascular outcomes. Activated vitamin D seems to be an inhibitor of the renin-angiotension-aldosterone system so it down regulates renin secretion to reduce blood pressure. In the pancreas， it is thought to promote insulin production to help reduce blood glucose. It is thought to be involved in autoimmune and anti-inflammatory processes. So there are many mechanisms that are also confirmed in animal models for why vitamin D might be beneficial to the heart in preventing atherosclerosis， hypertension and diabetes. Although we have that strong observational link， we are missing a key component right now and that is evidence-based randomized clinical trial data. There are studies ongoing， so we hope to have some information in five years or so. The critical question is， if someone is vitamin D deficient and we treat them with vitamin D， whether that can actually prevent a heart attack. That is a key piece that we don’t know. We have learned from prior experience that many of the other vitamins， the antioxidants like vitamin C and vitamin E and beta-carotene， looked really promising in observational data， but in clinical trials they were not shown to reduce heart attacks or cancer. Vitamin D might follow that same saga. I am hopeful it will be a little different with vitamin D because， although we call it a vitamin， it is actually a hormone that your body can make. If you have adequate sunlight and UVB exposure， your body can make all the vitamin D it needs. It is very different from the other antioxidants. We really do need more randomized clinical trial evidence before we can make recommendations about prescribing vitamin D for cardiovascular health.

　　Dr Michos: 即使低维生素D水平和心血管事件比如心脏病发作、卒中和死亡之间的联系较小，这仍然是我们观察到的唯一资料。在这其中可能存在残余混杂比如研究中入选的人们健康状况差并缺少户外活动，因此这有可能是他们为什么出现不好临床结果的原因。话虽如此，我们仍然有一些令人信服的生物学证据表明为什么说维生素D和心血管预后之间有切实的相关性。活性维生素D似乎是肾素-血管紧张素-醛固酮系统的阻断剂，因此它能减少肾素的分泌从而降低血压。在胰腺，维生素D还被认为能通过促进胰岛素分泌而降低血糖。维生素D还被认为参与了自身免疫和抗炎过程。因此还有很多机制被动物模型证实为何维生素D可能通过减慢动脉粥样硬化进程和降低血压以及预防糖尿病而使心脏获益。尽管我们在研究中得到了很多强有力的证据表明维生素D有益于心脏，胆识我们仍缺乏关键的证据，也就是基于证据的随机临床试验数据。现在已经有临床试验观察维生素D和心脏之间的关系，因此我们希望在5年或一段时间内能获得一些资料证实这种相关性。关键的问题是，我们用维生素D来治疗维生素D缺乏的患者是否会真的预防心血管疾病的发生。这是个非常关键的问题而我们现在并不清楚。我们根据以往的经验可知，很多其他的维生素，抗氧化物例如维生素C、维生素E以及β-胡萝卜素在研究资料中显示出了非常吸引人的作用，但是在临床试验中并没有显示出它们对心脏病和肿瘤有治疗效果。维生素D的结局也可能跟这些维生素一样。但是我希望维生素D和这些维生素有所不同，因为尽管我们称之为维生素，它实际上是一种人体能产生的激素。如果你能获得足够的光照和UVB暴露，你的身体就能产生所需的维生素D。它明显不同于其它的抗氧化物。实际上在我们推荐使用维生素D治疗心血管疾病之前我们非常需要更多的随机临床试验证据来证明它的有效性。