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Clin Infect Dis. 2019 Aug 17. pii: ciz801. doi: 10.1093/cid/ciz801. [Epub ahead of print]

Effect of monthly high-dose vitamin D supplementation on acute respiratory infections in older adults: A randomized controlled trial.

Author information

1
Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
2
School of Population Health, University of Auckland, Auckland, NZ.
3
Department of Public Health and Primary Care, University of Cambridge, UK.
4
Department of General Practice, University of Otago, Christchurch, NZ.

Abstract

BACKGROUND:

Although adults with low vitamin D status are at increased risk of acute respiratory infection (ARI), randomized controlled trials of vitamin D supplementation have provided inconsistent results.

METHODS:

We performed a randomized, double-blinded, placebo-controlled trial of 5,110 adults, aged 50-84 years. In 2011-2012, participants were randomized to an initial oral dose of 200,000 IU vitamin D3 followed by 100,000 IU monthly (n=2,558) or placebo (n=2,552) until late 2013 (median follow-up 1.6 years). Participants reported upper and lower ARIs on monthly questionnaires. Cox models analyzed time to first ARI (upper or lower) by treatment group.

RESULTS:

Participants' mean age was 66 years and 58% were male; 83% were of European/Other ethnicity, with the rest Maori, Polynesian or South Asian. Mean (SD) baseline blood 25-hydroxyvitamin D (25OHD) level was 63 (24) nmol/L; 25% were <50 nmol/L. In a random sample (n=441), vitamin D supplementation increased mean 25OHD to 135 nmol/L at 3 years, while those on placebo stayed at 63 nmol/L. During follow-up, 3,737 participants reported at least one ARI: 74.1% in the vitamin D group versus 73.7% in the placebo group. The hazard ratio for vitamin D compared to placebo was 1.01 (95%CI, 0.94, 1.07). Similar results were seen in most subgroups, including those with baseline 25OHD <50 nmol/L and in analyses of the upper/lower components of the ARI outcome.

CONCLUSIONS:

Monthly high-dose vitamin D supplementation does not prevent ARI in older adults with a low prevalence of profound vitamin D deficiency at baseline. Whether effects of daily or weekly dosing differ requires further study.

TRIAL REGISTRATION:

Australian New Zealand Clinical Trials Registry, Identifier ACTRN12611000402943.

KEYWORDS:

acute respiratory infection; adults; randomized controlled trial; supplement; vitamin D

PMID:
31420647
DOI:
10.1093/cid/ciz801

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