618 Journal of the College of Physicians and Surgeons Pakistan 2018, Vol. 28 (8): 618-622 INTRODUCTION Bone, skeletal muscle, brain, heart, prostate, colon, breast tissues and immune cells have Vitamin D receptors which are sensitive to the active form, calcitriol, also known as 1,25 dihydroxyvitamin D or 1,25 (OH) 2 D. 1 Apart from its well-known effects on bone turnover, clinical studies suggest that extra-skeletal effects of Vitamin D are substantial in severe deficiency of Vitamin D. Age- related alterations may lead to decreased formation of the active form of Vitamin D. 2 Less than 20 ng/mL (50 nmol/L) of 25-hydroxyvitamin D is defined as Vitamin D deficiency. Vitamin D deficiency is commonly seen in nursing home residents and has to do with a reduction in mobility, time spent outdoors with sun exposure, intrinsic skin response to ultraviolet radiation, inadequate dietary Vitamin D intake, impaired absorption, liver/kidney dysfunction, multiple comorbidities, and possibly polypharmacy. 3,4 The prevalence of Vitamin D deficiency in nursing home residents was found to be extremely high (from 79 to 98%). 5,6 In nursing homes, Vitamin D supplementation is increasingly considered to be a standard of care and, therefore, part of a good medical practice for elderly care. 3 There is considerable discussion about optimum serum concentrations of 25-hyroxyvitamin D. The prevalence of 25-hydroxyvitamin D deficiency affects more than 25% of community-dwelling elderly and the prevalence of deficiency is almost doubled among nursing home residents. 7 It was reported that more than half of physicians systematically prescribe Vitamin D in Belgium, because they believe nursing home residents are mostly deficient in Vitamin D. 8 Vitamin D supplementation may contribute to improved health status, musculoskeletal performance and reduce the risk of falls by improving strength, balance and elderly death in nursing homes. 9 The purpose of the current study was primarily to evaluate the effectiveness of daily, weekly moderate and weekly high administration of emulsified oil drop Vitamin D supplements in nursing home residents. ORIGINAL ARTICLE High versus Moderate Dosage of Daily and Weekly Administration of Vitamin D Supplements in the Form of Oil Drop in Nursing Home Residents Rezzan Mol 1 , Ahmet Dogukan Kansu 2 , Tamer Cebe 2 , Sadik Yildiz 1 , Vildan Kandemir Butun 1 , Bahadir Simsek 2 and Ufuk Cakatay 3 ABSTRACT Objective: To investigate the effectiveness of daily (800 IU), weekly-moderate (5600 IU) and weekly-high (8000 IU) supplementation of Vitamin D in nursing home residents. Study Design: A descriptive study. Place and Duration of Study: Nursing Home, MEVA, Istanbul, Turkey, from July 2016 to July 2017. Methodology: Nursing home residents were divided into 3 groups for supplementation of Vitamin D: Daily Dose Group (DDG), Weekly Dose Group-moderate (WDG-moderate) and Weekly Dose Group-high (WDG-high). Blood and physical performance tests were done initially to obtain a baseline value and the tests were repeated at 13th and 26th weeks of supplementation. Statistical analysis was conducted only on patients who were able to complete the 6-month-long study. Results: WDG-moderate (5600 IU/week) supplementation is found to be the most effective intervention in our study [25 (OH) D from 23.50 ±12.67 ng/mL to 37.38 ±14.42 ng/mL]. In WDG-moderate, the resulting Vitamin D level was found to reach near-optimum therapeutic levels. Only a limited increase was observed in 25 (OH) D level of DDG and WDG- high at the end of 26 weeks. Conclusion: Weekly (5600 IU/week) moderate supplementation of Vitamin D could be more beneficial than weekly (8000/week) high supplementation among nursing home residents. Multi-drug use among nursing home residents may hinder the therapeutic efficiency of Vitamin D administration. Physical performance tests may fail to demonstrate increased performance in mobility after Vitamin D administration in nursing home residents. Key Words: Vitamin D. Vitamin D supplementation. Nursing home. Elderly. Optimum Vitamin D dosage. Polypharmacy. 1 Department of Nursing Home, MEVA, Istanbul, Turkey. 2 Department of Medicine / Medical Biochemistry 3 , Istanbul University, Istanbul, Turkey. Correspondence: Prof. Dr. Ufuk Cakatay, Department of Medical Biochemistry, Cerrahpasa Faculty of Medicine Istanbul, Turkey. E-mail: cakatay@yahoo.com Received: December 12, 2017; Accepted: May 04, 2018.