Effect of vitamin D supplementation on the clinical conditions in the institutionalized elderly subjects

尽管有了新的强效抗微生物药物，肺炎仍是老年人死亡的常见原因。维生素D缺乏症在住院老年人中尤为常见，这可能是由于日照不足、皮肤病和饮食摄入问题造成的。维生素D缺乏症与髋部骨折以及心血管疾病、癌症和糖尿病等危及生命的疾病造成的更高死亡率有关。最近，1,25-二羟基维生素D， VD的一种生物活性形式，被报道为适应性免疫系统的有效免疫调节剂，并在感染时刺激先天免疫反应。第一项研究的目的是检查VD缺乏是否与长期护理机构的老年居民的细胞免疫功能低下和呼吸道感染易感性增加有关。我们测量了1,25-二羟基维生素D和白蛋白的血清浓度，进行了结核菌素皮肤试验（细胞免疫指标），并回顾性评估了发热性呼吸道疾病和肺炎的发病率。在第一项研究中，我们发现，在住院老年人中，较低的血清1,25-二羟基维生素D水平与结核菌素反应下降和呼吸道感染易感性增加相关。在第二项研究中，我们进行了一项前瞻性研究，以确定补充VD对通常血清VD水平低且肺炎高风险的虚弱老年人的发热性呼吸系统疾病的影响。因此，我们没有发现补充VD对机构体弱老年人的显著影响。

Pneumonia is a common cause of death among older people despite the availability of potent new antimicrobials. Vitamin D (VD) deficiency is especially common in institutionalized elderly people probably due to limited sun-exposure, skin diseases and problems of dietary intake and is associated with hip fractures and higher mortality from life-threatening conditions such as cardiovascular diseases, cancer and diabetes mellitus. Recently, 1,25-dihydroxyvitamin D, a biologically active form of VD, was reported to be a potent immune modulator of the adaptive immune system and to stimulate the innate immune response upon infection. The aim of the first study was to examine whether VD deficiency correlates with depressed cellular immunity and increases susceptibility to respiratory tract infections among older residents of long-term care facilities. We measured serum concentrations of 1,25-dihydroxyvitamin D and albumin, performed a tuberculin skin test, an indicator of cellular immunity and assessed retrospectively the incidence of both febrile respiratory illnesses and pneumonia. In the first study we showed that a lower serum level of 1,25-dihydroxyvitamin D correlated with a depressed tuberculin response and an increased susceptibility to respiratory tract infections in the institutionalized elderly subjects. In the second study, we performed a prospective study to determine the effect of VD supplementation on the febrile respiratory illnesses in frail elderly people who often have low serum VD levels and are at high risk for pneumonia. As a result, we could find no significant effects in the VD supplementation in institutionalized frail elderly subjects.