Trial reportEuropean journal of pediatrics2011
The effect of vitamin C on upper respiratory infections in adolescent swimmers: a randomized trial.
Trial report in European journal of pediatrics, 2011. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 17 papers, 6 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
17 citing papers in PubMed, 6 syntheses or guidelines pooled it, 38 citations in OpenAlex.
- Vitamin C reduces the severity of common colds: a meta-analysis.BMC public health · 2023Pooled it
- Select Dietary Supplement Ingredients for Preserving and Protecting the Immune System in Healthy Individuals: A Systematic Review.Nutrients · 2022Pooled it
- Pooled it
- Efficacy of vitamin C for the prevention and treatment of upper respiratory tract infection. A meta-analysis in children.European journal of clinical pharmacology · 2019Pooled it
- Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials.BioMed research international · 2018Pooled it
- Vitamin C for preventing and treating the common cold.The Cochrane database of systematic reviews · 2013Pooled it
- Trial
- The Effect of Olive Leaf Extract on Upper Respiratory Illness in High School Athletes: A Randomised Control Trial.Nutrients · 2019Trial
- Probiotics and vitamin C for the prevention of respiratory tract infections in children attending preschool: a randomised controlled pilot study.European journal of clinical nutrition · 2015Trial
- Are the UK's vitamin C recommendations evidence-based? A critical comment.The British journal of nutrition · 2026Review
- Review
- Article
- The Role of Micronutrients in Support of the Immune Response against Viral Infections.Nutrients · 2020Review
- A Review of Micronutrients and the Immune System-Working in Harmony to Reduce the Risk of Infection.Nutrients · 2020Review
- Vitamin C and Infections.Nutrients · 2017Review
- The effect of vitamin C on bronchoconstriction and respiratory symptoms caused by exercise: a review and statistical analysis.Allergy, asthma, and clinical immunology : official journal of the Canadian Society of Allergy and Clinical Immunology · 2014Review
- Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma.Clinical and translational allergy · 2011Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
6 authors at 5 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The risk of upper respiratory infections (URIs) is increased in people who are under heavy physical stress, including recreational and competitive swimmers. Additional treatment options are needed, especially in the younger age group. The aim of this study was to determine whether 1 g/day vitamin C supplementation affects the rate, length, or severity of URIs in adolescent swimmers. We carried out a randomized, double-blind, placebo-controlled trial during three winter months, among 39 competitive young swimmers (mean age 13.8 ± 1.6 years) in Jerusalem, Israel. Vitamin C had no effect on the incidence of URIs (rate ratio = 1.01; 95% confidence interval (CI) = 0.70-1.46). The duration of respiratory infections was 22% shorter in vitamin C group, but the difference was not statistically significant. However, we found a significant interaction between vitamin C effect and sex, so that vitamin C shortened the duration of infections in male swimmers by 47% (95% CI: -80% to -14%), but had no effect on female swimmers (difference in duration: +17%; 95% CI: -38% to +71%). The effect of vitamin C on the severity of URIs was also different between male and female swimmers, so that vitamin C was beneficial for males, but not for females. Our study indicates that vitamin C does not affect the rate of respiratory infections in competitive swimmers. Nevertheless, we found that vitamin C decreased the duration and severity of respiratory infections in male swimmers, but not in females. This finding warrants further research.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.