維生素D濃度與動脈硬化相關性研究

　　2011年北曼哈頓學術研究証實，血25-烴-維生素D濃度偏低與人體動脈硬化有關。 　　2011年8月在Stroke期刊指出，北曼哈頓學術研究証實，血維生素D濃度偏低與人體的動脈硬化有關。研究團隊指出，血25-烴-維生素D濃度降低與頸動脈內膜、中膜厚度增加及頸動脈斑塊最大厚度皆相關(Investigators have identified new evidence from the Northern Manhattan Study connecting low vitamin-D levels to atherosclerosis. They found that low 25-hydroxy- vitamin-D levels were associated with increased intima-media and maximal carotid thickness in those with plaque)。

　　研究一共有203位成年人參與，所有人都抽血檢測血中25-烴-維生素D、1, 25-烴-維生素D、Ca、P、PTH濃度，並且施行頸動脈超音波掃描((The investigators studied 203 adults from the Northern Manhattan Study who had serum measurements and carotid ultrasound. They looked at 25-hydroxy vitamin D, 1,25- dihydroxy vitamin D, calcium, phosphorus, and parathyroid hormone)。結果顯示，有57%患者有頸動脈硬化斑塊，其斑塊數目與血磷濃度(p=0.02)和鈣磷乘積(p=0.03)相關(The majority of those studied—57%—had plaque, and investigators found the association of plaque number with phosphorus and calcium- phosphorus product persisted)。此外，25-烴-維生素D與頸動脈內-中膜厚度及頸動脈斑塊最大厚度呈反比(25-hydroxy vitamin D was inversely associated with both intima-media thickness (p=0.05) and maximal carotid plaque thickness (p=0.03))，但血鈣、PTH、1,25雙烴基維生素D均與頸動脈內-中膜厚度無關。

　　此外，在一項學術討論會中，Dr. Michos博士表示：動物模型已經證實，維生素D可經由多種機制來減緩動脈粥樣硬化、降低血壓和糖尿病，從而使心臟得利(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)，認為維生素D是腎素-血管緊張素-醛固酮系統的阻斷劑，它能減少腎素分泌，從而降低血壓(Activated vitamin D seems to be an inhibitor of the renin-angiotension-aldosterone system so it down regulates renin secretion to reduce blood pressure)；維生素D可提升胰島素分泌而降低血糖(to promote insulin production to help reduce blood glucose)；另外，維生素D還可能參與自身免疫和抗炎過程(It is thought to be involved in autoimmune and anti- inflammatory processes)。但目前仍缺乏大型隨機臨床試驗來證實，應用維生素D來治療維生素D缺乏患者是否會真的可以預防心血管疾病，這個情況如同維生素C、維生素E以及β-胡蘿蔔素在動物研究中顯示出非常傑出的作用，但在人體臨床試驗中並無顯示維生素C、維生素E及β-胡蘿蔔素對腫瘤及心血管疾病有滿意的治療效果。

維生素D、動脈硬化、基礎醫學、頸動脈、糖尿病、心血管疾病、維生素、胡蘿蔔素