The use of dietary supplements may be beneficial for preventing and treating viral RTI, concluded a study published in "Expert review of respiratory medicine". Databases such as Google Scholar, PubMed, Web of Science, and Scopus were explored to examine the randomized controlled trials that assessed the efficacy of consuming dietary supplements to prevent and treat viral RTIs.

A total of 39 randomized controlled trials (n=16,797 participants) were incorporated in this systematic review. The supplementation of vitamin D led to improvement in viral RTI in people who have a deficiency of vitamin D. Among the dietary supplements, specific lactobacillus strains were utilized most frequently with selected prebiotics that displayed substantially positive effects to prevent and treat viral RTIs. Also, ginseng extract supplementation as an adjuvant therapy seems to be beneficial to prevent viral RTIs.

But, there is a requisition of longitudinal research to verify these observations and for addressing the optimal dose, safety, and duration of dietary supplements being publicly recommended, concluded the study authors.