Effect of monthly vitamin D3 supplementation in healthy adults on adverse effects of earthquakes: randomised controlled trial.

OBJECTIVE: To determine whether supplementation with vitamin D improves resilience to the adverse effects of earthquakes. DESIGN: Opportunistic addition to an established randomised double blind placebo controlled trial. SETTING: Christchurch, New Zealand, where a prolonged series of catastrophic earthquakes beginning on 4 September 2010 occurred, which caused widespread destruction, fatalities, and extensive psychological damage. PARTICIPANTS: 322 healthy adults (241 women; 81 men) aged 18-67 who were already participating in the vitamin D and acute respiratory infections study (VIDARIS) between February 2010 and November 2011. INTERVENTION: Participants were randomised to receive an oral dose of either 200,000 IU vitamin D3 monthly for two months then 100,000 IU monthly (n=161) or placebo (n=161) for a total of 18 months. MAIN OUTCOME MEASURE: This is a post hoc analysis from the previously published VIDARIS trial. The primary endpoint in the current analysis was the self reported effects and overall adverse impact of the Christchurch earthquakes as assessed by questionnaire four months after the most destructive earthquake on 22 February 2011, which was used as the index event. The secondary end point was the number of "psychological" adverse events that participants reported at their usual monthly appointments as part of the original VIDARIS trial. RESULTS: 308 participants completed the earthquake impact questionnaire (n=152 in the vitamin D group and 156 in the placebo group). There was no significant difference in the number of self reported adverse effects between those receiving vitamin D supplementation and those receiving placebo. There was also no difference in the overall adverse impact score between treatment groups (χ(2) P=0.44). The exception was that those in the vitamin D group experienced more adverse effects on family relationships (22% v 13%; χ(2) P=0.03). The number of psychological adverse events-such as fatigue, stress, anxiety, and insomnia-that participants reported at their usual monthly appointments was significantly higher after the earthquake (χ(2) P=0.007) but did not differ between treatment groups. CONCLUSION: In this trial, vitamin D supplementation did not reduce the adverse impact of earthquakes in healthy adults. Trial registration Australian New Zealand Clinical Trials Registry (anzctr.org.au) ACTRN12609000486224.

Long-term high-dose vitamin D3 supplementation and blood pressure in healthy adults: a randomized controlled trial.

Previous randomized controlled trials of vitamin D supplementation and blood pressure (BP) mainly have given vitamin D for short periods (<6 months) or at low doses (400 IU per day). This study aims to determine whether long-term high-dose vitamin D taken for 18 months lowers BP. Adults were recruited from a healthcare organization or university into a double-blind controlled trial and randomized to receive either vitamin D3 200 000 IU for 2 months followed by 100 000 IU monthly up to 18 months (n=161) or placebo (n=161). BP was measured at baseline, 5, and 18 months. Subjects had a mean (SD) age of 47.6 (9.7) years, 75% were women, and 94% were of European ancestry (white). Mean (SD) 25-hydroxyvitamin D3 changed from 73 (22) nmol/L at baseline to 124 (28) nmol/L at 18 months in the vitamin D group, and from 71 (22) nmol/L to 56 (22) nmol/L in the placebo group. Mean BP was similar for the vitamin D and placebo groups at baseline (123.4/76.3 versus 122.6/75.6 mm Hg; respectively). The mean change (95% confidence interval) in BP at 18 months minus baseline in the vitamin D group compared with placebo group was -0.6 (-2.8 to 1.6) mm Hg for systolic (P=0.61) and 0.5 (-1.1, 2.2) mm Hg for diastolic (P=0.53). Long-term vitamin D supplementation, which increased mean 25-hydroxyvitamin D3 concentration >100 nmol/L for 18 months, had no effect on systolic or diastolic BP in predominantly white, healthy adults without severe vitamin D deficiency. Beneficial effects on BP cannot be ruled out for other populations.

Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: the VIDARIS randomized controlled trial.

CONTEXT: Observational studies have reported an inverse association between serum 25-hydroxyvitamin D (25-OHD) levels and incidence of upper respiratory tract infections (URTIs). However, results of clinical trials of vitamin D supplementation have been inconclusive. OBJECTIVE: To determine the effect of vitamin D supplementation on incidence and severity of URTIs in healthy adults. DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind, placebo-controlled trial conducted among 322 healthy adults between February 2010 and November 2011 in Christchurch, New Zealand. INTERVENTION: Participants were randomly assigned to receive an initial dose of 200,000 IU oral vitamin D3, then 200,000 IU 1 month later, then 100,000 IU monthly (n = 161), or placebo administered in an identical dosing regimen (n = 161), for a total of 18 months. MAIN OUTCOME MEASURES: The primary end point was number of URTI episodes. Secondary end points were duration of URTI episodes, severity of URTI episodes, and number of days of missed work due to URTI episodes. RESULTS: The mean baseline 25-OHD level of participants was 29 (SD, 9) ng/mL. Vitamin D supplementation resulted in an increase in serum 25-OHD levels that was maintained at greater than 48 ng/mL throughout the study. There were 593 URTI episodes in the vitamin D group and 611 in the placebo group, with no statistically significant differences in the number of URTIs per participant (mean, 3.7 per person in the vitamin D group and 3.8 per person in the placebo group; risk ratio, 0.97; 95% CI, 0.85-1.11), number of days of missed work as a result of URTIs (mean, 0.76 days in each group; risk ratio, 1.03; 95% CI, 0.81-1.30), duration of symptoms per episode (mean, 12 days in each group; risk ratio, 0.96; 95% CI, 0.73-1.25), or severity of URTI episodes. These findings remained unchanged when the analysis was repeated by season and by baseline 25-OHD levels. CONCLUSION: In this trial, monthly administration of 100,000 IU of vitamin D did not reduce the incidence or severity of URTIs in healthy adults. TRIAL REGISTRATION: anzctr.org.au Identifier: ACTRN12609000486224.