Randomized Controlled Trial of Vitamin D3 Supplementation for Viral Upper Respiratory Tract Infections (URI) Prevention

A Randomized Controlled Trial of Vitamin D3 Supplementation for the Prevention of Viral Upper Respiratory Tract Infections

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00656929

Enrollment

167

Registered

2008-04-11

Start date

2006-12-31

Completion date

2007-06-30

Last updated

2008-04-11

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Viral Upper Respiratory Tract Infection

Keywords

Vitamin D, Viral URI, Influenza, Colds

Brief summary

Background: Vitamin D has been shown to be an important immune system regulator. Vitamin D insufficiency during the winter may cause increased susceptibility to infections, particularly viral upper respiratory tract infections (URIs). Objective: To determine whether vitamin D supplementation during the winter season prevents or decreases URI symptoms in adults. Methods: A randomized, double-blind, placebo-controlled trial was conducted in 162 adults. Participants were randomized to receive vitamin D3 50 mcg (2000 IU) daily or matching placebo for 12 weeks from December 2006 to March 2007. A biweekly questionnaire was used to record the incidence and severity of URI symptoms

Interventions

DIETARY_SUPPLEMENTVitamin D3

Vitamin D3 (cholecalciferol) 50 mcg (2000 IU) daily x 3 months

OTHERPlacebo

Placebo tablets

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

PREVENTION

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

ALL

Age

18 Years to 80 Years

Healthy volunteers

Yes

Inclusion criteria

* ambulatory adult age 18-80 and stable medical condition with no change in medications for 6 months prior to study entry.

Exclusion criteria

* morbid obesity (body mass index \> 35 kg/m2) * current tobacco use * history of hypercalcemia, nephrolithiasis or sarcoidosis * pregnancy * recent hospitalization * current liver or kidney disorders, malignancy and malabsorption * use of immunosuppressants or medications that interfere with vitamin D metabolism such as phenytoin and carbamazepine.

Design outcomes

Primary

Measure	Time frame
To see whether vitamin D3 supplementation during the winter prevents viral URI.	3 months

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026