Daily vitamin D supplementation can reduce the incidence of acute respiratory infection

Daily vitamin D supplementation can reduce the incidence of acute respiratory infection

A meta-analysis of 43 randomised controlled trials published in 'The Lancet' in May 2021 found that vitamin D supplementation was associated with a lower risk of acquiring acute respiratory infection in results from more than 43,000 participants, and concluded a pronounced effect in children aged 1 - 18 years taking doses of 400 - 1000IU Vitamin D3 on a daily basis which resulted in a 30% reduction in risk of experiencing at least 1 respiratory tract infection.

This study backs up findings from a previous meta-analysis conducted in 2017 which found that daily and weekly supplementation with vitamin D was associated with lower risk of acute respiratory tract infection in all participants, but that large infrequent bolus doses of vitamin D had no effect.

Acute Respiratory Infection (ARI) is defined by any episode of cold or flu with at least one of the following symptoms: fever, chills, sore throat, runny nose, or cough over 4 consecutive weeks. In 2008 to 2009 an Australian National Survey was conducted to extrapolate the prevalence of ARI by season and state, and to estimate the incidence of ARI in the Australian community. 19·9% (1505/7578) of respondents reported an ARI in the previous 4 weeks, suggesting an incidence of 68·9 million cases of ARI occurring in Australia each year, indicating that ARI imposes a significant national burden on society.

Vitamin D deficiency has been shown to increase the risk of acquiring upper respiratory tract infections. Vitamin D also appears to inhibit pulmonary inflammatory responses while enhancing innate defence mechanisms against respiratory pathogens.


1. Jolliffe D, Camargo C, Sluyter J, Aglipay M, Aloia J, Ganmaa D et al. Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials. The Lancet Diabetes & Endocrinology [Internet]. 2021 [cited 18 May 2021];9(5):276-292. Available from: https://www.thelancet.com/

2. Epidemiology and Infection: Incidence of acute respiratory infections in Australia


3. Clinical & Experimental Immunology: Vitamin D and Respiratory Health:


4. The Lancet - Diabetes & Endocrinology: Vitamin D and Respiratory Infections