Effect of Vitamin C Supplements on Respiratory Tract Infections: A Systematic Review and Meta-Analysis

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#ascorbic-acid #dietary-supplements #humans #incidence #respiratory-tract-infections

Effect of Vitamin C Supplements on Respiratory Tract Infections: A Systematic Review and Meta-Analysis

Keya et al., 2022 | Curr Rev Clin Exp Pharmacol | Meta Analysis

Citation

Keya Tahmina Afrose, Leela Anthony, ... Rashid Mumunur. Effect of Vitamin C Supplements on Respiratory Tract Infections: A Systematic Review and Meta-Analysis. Curr Rev Clin Exp Pharmacol. 2022;17(3):205-215. doi:10.2174/2772432817666211230100723

Abstract

BACKGROUND: Respiratory tract infections are a primary cause of illness and mortality over the world. OBJECTIVE: This study was aimed to investigate the effectiveness of vitamin C supplementation in preventing and treating respiratory tract infections. METHODS: We used the Cochrane, PubMed, and MEDLINE Ovid databases to conduct our search. The inclusion criteria were placebo-controlled trials. Random effects meta-analyses were performed to measure the pooled effects of vitamin C supplementation on the incidence, severity, and duration of respiratory illness. RESULTS: We found ten studies that met our inclusion criteria out of a total of 2758. The pooled risk ratio (RR) of developing respiratory illness when taking vitamin C regularly across the study period was 0.94 (with a 95% confidence interval of 0.87 to 1.01) which found that supplementing with vitamin C lowers the occurrence of illness. This effect, however, was statistically insignificant (P= 0.09). This study showed that vitamin C supplementation had no consistent effect on the severity of respiratory illness (SMD 0.14, 95% CI -0.02 to 0.30: I2 = 22%, P=0.09). However, our study revealed that vitamin C group had a considerably shorter duration of respiratory infection (SMD -0.36, 95% CI -0.62 to -0.09, P = 0.01). CONCLUSION: Benefits of normal vitamin C supplementation for reducing the duration of respiratory tract illness were supported by our meta-analysis findings. Since few trials have examined the effects of therapeutic supplementation, further research is needed in this area.

Key Findings

We found ten studies that met our inclusion criteria out of a total of 2758. The pooled risk ratio (RR) of developing respiratory illness when taking vitamin C regularly across the study period was 0.94 (with a 95% confidence interval of 0.87 to 1.01) which found that supplementing with vitamin C lowers the occurrence of illness. This effect, however, was statistically insignificant (P= 0.09). This study showed that vitamin C supplementation had no consistent effect on the severity of respirator

Outcomes Measured

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Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition See abstract

MeSH Terms

  • Ascorbic Acid
  • Dietary Supplements
  • Humans
  • Incidence
  • Respiratory Tract Infections
  • Vitamins

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Meta-Analysis, Systematic Review, Journal Article
  • Vertical: vitamin-c

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09