The effect of vitamin D supplementation on acute respiratory tract infection in older Australian adults

The effect of vitamin D supplementation on acute respiratory tract infection in older Australian adults

an analysis of data from the D-Health Trial

[Posted 22/Feb/2021]

AUDIENCE: Endocrinology, Internal Medicine

KEY FINDINGS: Monthly bolus doses of 60,000 IU of vitamin D did not reduce the overall risk of acute respiratory tract infection but could slightly reduce the duration of symptoms in the general population. These findings suggest that routine vitamin D supplementation of a population that is largely vitamin D replete is unlikely to have a clinically relevant effect on acute respiratory tract infection.

BACKGROUND: Observational studies have linked vitamin D deficiency with acute respiratory tract infection but results from randomized controlled trials are heterogeneous. We analyzed data from the D-Health Trial to determine whether supplementing older Australian adults, recruited from the general population, with monthly doses of vitamin D reduced the risk, duration, and severity of acute respiratory tract infections.

DETAILS: Data from the D-Health Trial, a randomized, double-blind, placebo-controlled trial of monthly vitamin D supplementation, for which acute respiratory infection was a pre-specified trial outcome was collected. Participants were supplemented and followed for up to 5 years. Participants were men and women aged 60 to 79 years (with volunteers up to age 84 years). Participants were randomly assigned to receive either vitamin D or placebo (1:1) using computer-generated permuted block randomization, which was stratified by age, sex, and state. Participants were asked to report occurrence of acute respiratory symptoms over the previous month via annual surveys, and a subset of participants completed 8-week respiratory symptom diaries in winter. Blood samples were obtained from a random sample of participants (about 450 per group per year) and serum 25-hydroxy vitamin D (25[OH]D) concentrations were measured to monitor adherence. 21,315 participants were recruited and randomized. Of the 16,000 participants selected for potential analysis of survey data, 15,373 were included in the analysis; 295 in the vitamin D group and 332 in the placebo group who were missing data for all five annual surveys were excluded from the analysis. Of the 3800 selected for potential analysis of diary data, 3070 were invited to complete the diaries because 730 had already withdrawn. 2598 people were included in the analysis; 218 people in the vitamin D group and 254 in the placebo group were missing data and were therefore excluded from the analysis. In blood samples collected from randomly sampled participants throughout the trial, the mean serum 25(OH)D concentration was 114.8 (SD 30.3) nmol/L in the vitamin D group and 77.5 (25.2) nmol/L in the placebo group. Vitamin D supplementation did not reduce the risk of acute respiratory tract infection (survey OR 0.98, 95% CI 0.93 to 1.02; diary OR 0.98, 0.83 to 1.15). Analyses of diary data showed reductions in the overall duration of symptoms and of severe symptoms, but these were small and unlikely to be clinically significant.

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Source: Pham, H., Waterhouse, M., Baxter, C., Duarte Romero, B., McLeod, D. S. A., Armstrong, B. K., et al. (2021). The effect of vitamin D supplementation on acute respiratory tract infection in older Australian adults: an analysis of data from the D-Health Trial. The Lancet Diabetes and Endocrinology, 9(2) 69-81. Published: February 1, 2021. DOI: 10.1016/S2213-8587(20)30380-6