High-dose vitamin D supplementation was superior to standard doses in the reduction of acute respiratory infection (ARI) among long-term care (LTC) residents, according to a study published recently in the Journal of the American Geriatrics Society.1 Vitamin D has been shown in previous studies to enhance the native immune response to infections.2
An investigation led by Adit Ginde, MD, MPH, professor of emergency medicine at the University of Colorado School of Medicine, of 55 residents of various LTC facilities in Colorado found a 40% reduction in ARI among those given 3,000-4,000 UI/d of vitamin D compared with a control group of 52 residents given standard doses of 400-1000 UI/d.
The LTC group was chosen for study due to a known reduced immune response among older individuals3,4 who are also at higher risk of both ARI and vitamin D deficiency.5,6
The two randomized vitamin D dosage groups (high vs standard) were followed for 12 months, to assess the incidence of both upper and lower respiratory tract infections during that period. The incidence of upper ARIs, including colds, sinusitis, pharyngitis and otitis media was significantly reduced in the high-dose group compared to the standard dose (0.44 vs 0.84; P =.02), as was the incidence of skin and soft tissue infections (0.13 vs 0.40; P =.02).
Subsequent analysis of secondary outcomes revealed little difference between the two groups in the incidence of lower ARIs (acute bronchitis, influenza, pneumonia), as well as rates of hospitalizations for all causes (46% high dose vs 43% standard dose) and deaths (22% high dose vs 21% standard dose).
One feature that stood out between the groups was the higher incidence of falls in the high-dose group—36% taking high-dose vitamin D experienced one fall during the 12 month follow-up period compared to 29% taking standard dose—which Dr. Ginde suggested might be attributed to several factors. “It could be related to unmeasured differences in baseline characteristics, such as ‘frequent fallers’ being randomized to the high dose group by chance,” he explained, “or by increased mobility causing increased falls, or some physiologic dysregulation caused by high, bolus dosing of vitamin D.”
Although surprising, the higher rate of falls did not result in a greater number of fractures in the high-dose group. “Our trial was not designed to assess detailed causes of falls. Thus, the reason for a higher incidence of falls in the high dose vitamin D group is unknown,” he noted, although the study did point to “growing interest in the role of vitamin D in fall prevention, relating to muscle function and balance.”
Dr Ginde and his colleagues also observed that participants in the high-dose group demonstrated higher average body mass indices (BMIs), higher rates of chronic obstructive pulmonary disease (COPD) and diabetes, while also having lower average rates of smoking, asthma, coronary artery disease, and dementia, although the significance of these differences was not analyzed for the purposes of this study.
- Ginde AA, Blatchford P, Breese K, et al. High-dose monthly vitamin D for prevent on of acute respiratory infection in older long-term care residents: a random clinical trial. J Am Geriatr Soc. 2016. doi: 10.1111/jgs.14679
- Liu PT, Stenger S, Li H, et al. Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response. Science. 2006;311:1770–1773. doi: 10.1126/science.1123933
- Muder RR. Pneumonia in residents of long-term care facilities: Epidemiology, etiology, management, and prevention. Am J Med. 1998;105:319-330. doi: 10.1016/S0002-9343(98)00262-9
- Loeb M, McGeer A, McArthur M, Walter S, Simor AE. Risk factors for pneumonia and other lower respiratory tract infections in elderly residents of long-term care facilities. Arch Intern Med. 1999;159:2058-2064. doi: 10.1001/archinte.159.17.2058
- Ginde AA, Mansbach JM, Camargo CA Jr. Association between serum 25 hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey. Arch Intern Med. 2009;169:384-390. doi: 10.1001/archinternmed.2008.560
- Jolliffe DA, Griffiths CJ, Martineau AR. Vitamin D in the prevention of acute respiratory infection: Systematic review of clinical studies. J Steroid Biochem Mol Biol. 2013;136:321-329. doi: 10.1016/j.jsbmb.2012.11.017