Question explored with the scientific record
what supplements help children prevent ARIs
The short version: the evidence for supplements preventing respiratory infections in children is thin, mixed, and mostly about treating illness once it starts, not preventing it.
The most recent and largest pediatric trial, a 2025 meta-analysis of 17 randomized controlled trials with over 18,000 children, found that vitamin D supplementation did not reduce the overall incidence of acute respiratory infections [2]. The only signal was a possible benefit from very low daily doses (1000 IU or less), which cut the risk by about half, but higher doses showed no effect at all [2]. That pattern, where a low dose works and a high dose does not, is unusual and suggests the finding could be a statistical fluke or a sign that only deficient children benefit. The older 2010 study in adults that found a benefit used a threshold of 38 ng/mL, but that was a cohort study, not a trial, and it tested a different population [1].
For zinc, the 2023 trial in Pakistani infants found that 20 mg of zinc for 7 days shortened illness duration but did not clearly prevent infections from happening in the first place [4]. The adjusted incidence rate ratio was 0.89, meaning about an 11% reduction, but the confidence interval crossed 1.0, meaning the result was not statistically significant [4]. Older studies from the 1990s and early 2000s in developing countries showed larger reductions, but those were in populations with widespread zinc deficiency [5, 6]. For a well-nourished child in a developed country, the benefit is likely much smaller or absent.
| Supplement | What the evidence shows for prevention | Best evidence |
|---|---|---|
| Vitamin D | No overall reduction in ARI incidence in children [2] | 2025 meta-analysis, 18,372 children |
| Vitamin D (low dose only) | Possible 58% reduction, but only with ≤1000 IU/day [2] | Same meta-analysis, subgroup |
| Zinc | No significant prevention; shortens illness once started [4] | 2023 RCT, 120 infants |
| Probiotics | No good evidence for preventing respiratory infections in children [7, 8, 14] | Multiple RCTs, mostly for diarrhea |
The probiotics evidence is almost entirely about diarrhea, not respiratory infections. The umbrella meta-analysis from 2025 showed probiotics reduce diarrhea incidence and duration, but the respiratory data is absent from the retrieved evidence [14]. The one trial that tested probiotics for preventing ear infections in high-risk children found no benefit [8].
My call: for a generally healthy child, the evidence does not support routine use of any supplement to prevent respiratory infections. The only possible exception is vitamin D for a child who is genuinely deficient, but that requires a blood test to know. Confidence: moderate, because the largest pediatric trial is recent and well-designed, but the negative result is clear.
Sources used 30
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Serum 25-Hydroxyvitamin D and the Incidence of Acute Viral Respiratory Tract Infections in Healthy Adults
Prospective cohort study in healthy adults linking monthly 25-hydroxyvitamin D levels to incidence of acute viral respiratory tract infections, identifying a threshold of 38 ng/mL above which infection risk and illness burden were substantially reduced, suggesting vitamin D opti…
DOI: 10.1371/journal.pone.0011088 -
The role of vitamin D in the prevention and treatment of acute respiratory infections in pediatric populations: a systematic review and meta-analysis of randomized controlled trials
A comprehensive PRISMA-guided systematic review and meta-analysis of 17 randomized controlled trials (18,372 pediatric participants) found that vitamin D supplementation does not reduce overall ARI incidence or most clinical outcomes in children, though daily low-dose regimens (…
DOI: 10.1186/s12887-025-06361-6 -
Major Approaches to the Dosage of Vitamin D in the Elderly: A Systematic Review
A systematic review of vitamin D dosing in the elderly finds that maintaining serum 25(OH)D above 30 ng/mL with 1,000-2,000 IU daily reduces falls, fractures, and may improve COVID-19 outcomes.
DOI: 10.34256/mdnt2131 -
A Randomized Controlled Trial on Zinc Supplementation for Prevention of Acute Respiratory Infections in Infants
Zinc supplementation in Pakistani infants with acute respiratory infections shortened illness duration and raised serum zinc levels, with inconclusive or variable effects on ARI incidence.
DOI: 10.54393/pjhs.v4i04.696 -
Simultaneous Weekly Supplementation of Iron and Zinc Is Associated with Lower Morbidity Due to Diarrhea and Acute Lower Respiratory Infection in Bangladeshi Infants
This study evaluates the efficacy of simultaneous weekly supplementation of iron and zinc on reducing morbidity from diarrhea and acute lower respiratory infections in Bangladeshi infants, finding that such supplementation is associated with lower risks of these conditions, part…
DOI: 10.1093/jn/133.12.4150 -
Therapeutic and preventive effects of zinc on serious childhood infectious diseases in developing countries
This study reviews the therapeutic and preventive effects of zinc supplementation on diarrhea and other serious infectious diseases in children from developing countries, highlighting significant reductions in illness duration and incidence.
DOI: 10.1093/ajcn/68.2.476s -
Effect of probiotics supplementation on acute diarrhea in infants: a randomized double blind clinical trial
Add-on probiotic supplementation to standard therapy shortened diarrhea duration in infants with acute diarrhea and reduced treatment failures, with no adverse events observed.
DOI: 10.14238/pi47.4.2007.172-8 -
Probiotics and Prebiotics in Preventing Episodes of Acute Otitis Media in High-risk Children
This study investigates the efficacy of follow-up formula supplemented with probiotics and prebiotics in reducing the incidence of acute otitis media in high-risk children, finding no significant difference compared to placebo.
DOI: 10.1097/INF.0b013e31828df4f3 -
Acute Gastroenteritis
This paper discusses the management of acute gastroenteritis in children, emphasizing the importance of oral rehydration solutions and early dietary reintroduction while highlighting outdated practices and the role of pharmacologic therapies.
DOI: 10.1542/pir.33-11-487 -
Effects of exercise with probiotics, exercise alone, and probiotics alone on physical, motor, affective, and cognitive functions in stroke patients: a randomised controlled trial
Combining multimodal exercise with probiotic supplementation in stroke patients yields greater improvements across physical disability, motor function, mood, and cognition than either intervention alone, with exercise alone surpassing probiotics alone in physical and cognitive o…
DOI: 10.1186/s13102-025-01446-2 -
Effect of probiotic supplement (kidilact) on prevention of acute diarrhea in children: a double-blind randomized clinical trial
A double-blind randomized clinical trial in Iran (84 children, 6–60 months) tested the Kidilact probiotic against standard treatment for acute diarrhea; the probiotic reduced stool defecation frequency and improved some vital signs over 3 days, with no significant difference in …
DOI: 10.18203/2320-6012.ijrms20172595 -
Effect of probiotics plus zinc supplementation on clinical outcomes of infants and children with acute infectious diarrhea: a randomized controlled trial
Adding zinc to Lactobacillus rhamnosus GG probiotic therapy in infants and children with acute infectious diarrhea did not significantly change dehydration or overall disease severity by two weeks, but shortened healing time compared with probiotic therapy alone.
DOI: 10.3345/cep.2023.01340 -
The Effect of Feed Supplementation with EM Bokashi® Multimicrobial Probiotic Preparation on Selected Parameters of Sow Colostrum and Milk as Indicators of the Specific and Nonspecific Immune Response
This study on sows fed EM Bokashi multimicrobial probiotic evaluated changes in colostrum and milk immune quality, showing increased B-cell subpopulations and immune markers in treated animals, suggesting enhanced humoral and nonspecific mammary defense that may benefit piglet i…
DOI: 10.1007/s12602-021-09850-z -
Probiotics for pediatric diarrhea and constipation: an umbrella meta-analysis
An umbrella meta-analysis of 35 pediatric probiotic systematic reviews showing that probiotics reduce diarrhea incidence, prevalence, and duration and offer modest benefits for constipation, with high heterogeneity and strain-specific effects, highlighting the need for standardi…
DOI: 10.1186/s12887-025-06002-y -
Safety evaluation of HOWARU® Restore (Lactobacillus acidophilus NCFM, Lactobacillus paracasei Lpc-37, Bifidobacterium animalis subsp. lactis Bl-04 and B. lactis Bi-07) for antibiotic resistance, genomic risk factors, and acute toxicity
A comprehensive safety assessment of four probiotic strains (Lactobacillus acidophilus NCFM, L. paracasei Lpc-37, Bifidobacterium animalis subsp. lactis Bl-04, Bi-07) and the HOWARU Restore blend, combining in vitro antibiotic resistance testing, genome mining for virulence/toxi…
DOI: 10.1016/j.fct.2017.10.037 -
The protective effect of probiotic/prebiotic consumption against fatigue in the general population is modulated by BMI: an analysis of mediating and moderating effects based on NHANES
A cross-sectional analysis of NHANES data (2009–2018; n=3,791) finds that probiotic/prebiotic consumption is associated with a reduced fatigue risk in the general population, with higher BMI strengthening this protective association, while sleep duration, depression, and physica…
DOI: 10.1186/s40001-025-03129-7 -
The effect of probiotic supplementation on the clinical and para-clinical findings of multiple sclerosis: a randomized clinical trial
Saccharomyces boulardii probiotic supplementation for four months in relapsing-remitting MS reduces systemic inflammation and oxidative stress and improves pain, fatigue, mental health, and several quality-of-life measures compared with placebo.
DOI: 10.1038/s41598-023-46047-6 -
Surface-Specific Efficacy of Fluoride Varnish in Caries Prevention in the Primary Dentition: Results of a Community Randomized Clinical Trial
This study evaluates the surface-specific efficacy of fluoride varnish in preventing dental caries in the primary dentition of Aboriginal children, revealing a 25% reduction in caries risk, particularly benefiting sound tooth surfaces.
DOI: 10.1159/000344015 -
Vitamin A Supplementation: Implications for Morbidity and Mortality in Children
This article reviews decades of vitamin A supplementation trials in children, showing a roughly 30% reduction in total mortality with more pronounced benefits for measles mortality, while effects on diarrhea and respiratory infections vary by age, nutritional status, setting, an…
DOI: 10.1086/315921 -
Dexamethasone for Parapneumonic Pleural Effusion: A Randomized, Double-Blind, Clinical Trial
This study demonstrates that dexamethasone significantly reduces the time to recovery in children with parapneumonic pleural effusion compared to placebo, without increasing serious adverse events.
DOI: 10.1016/j.jpeds.2017.02.043 -
Treatment of Attention Deficit Hyperactivity Disorder in Children
This article reviews ADHD diagnosis and pharmacotherapy in children, highlighting the Multimodal Treatment Study of Children with ADHD (MTA) which found optimized pharmacotherapy to be more effective than behavioral therapy or routine community care, with no clear advantage of c…
DOI: 10.1345/aph.10353 -
A low intensity, community based lifestyle programme to prevent weight gain in women with young children: cluster randomised controlled trial
This study evaluates the effectiveness of a low-intensity, community-based lifestyle program in preventing weight gain among women with young children, demonstrating a significant weight loss in the intervention group compared to the control group over 12 months.
DOI: 10.1136/bmj.c3215 -
Secondhand Smoke Exposure Reduction Intervention in Chinese Households of Young Children: A Randomized Controlled Trial
This study evaluates the effectiveness of a community health worker-delivered smoking hygiene intervention in reducing secondhand smoke exposure among young children in Chinese households, demonstrating significant improvements in smoking restrictions and lower cotinine levels i…
DOI: 10.1016/j.acap.2015.06.008 -
An Integrated Child Nutrition Intervention Improved Growth of Younger, More Malnourished Children in Northern Viet Nam
A randomized, community-based evaluation of Save the Children’s integrated nutrition program (CENP) in rural northern Vietnam found no overall growth benefit, but younger children (≤15 months) who were more malnourished at baseline experienced modest improvements in weight-for-a…
DOI: 10.1177/15648265020234S208 -
A randomized clinical trial to arrest dentin caries in young children using silver diamine fluoride
A randomized, community-based clinical trial in Thailand comparing 38% silver diamine fluoride (SDF) with 5% sodium fluoride varnish (NaF) applied semiannually in 1–3 year-old children at high caries risk shows that SDF more effectively arrests dentin caries over 12 months, with…
DOI: 10.1016/j.jdent.2020.103375 -
Design and sample characteristics of COordinated Oral health Promotion (CO-OP) Chicago: A cluster-randomized controlled trial
This paper describes the design, sampling, and baseline characteristics of CO-OP Chicago, a cluster-randomized trial evaluating a community health worker intervention to improve oral health behaviors among low-income urban children under three years old.
DOI: 10.1016/J.CCT.2019.105919 -
Analysis of serious adverse events in a pediatric community-acquired pneumonia randomized clinical trial in Malawi
Double-blind randomized non-inferiority trial in Malawi shows 3 days of amoxicillin for non-severe chest-indrawing pneumonia in HIV-uninfected children is non-inferior to 5 days with no increase in serious adverse events; SAEs were rare, with higher risk in male and younger chil…
DOI: 10.1038/s41598-022-07582-w -
RANDOM SPATIAL DISTRIBUTION OF SCHISTOSOMA MANSONI AND HOOKWORM INFECTIONS AMONG SCHOOL CHILDREN WITHIN A SINGLE VILLAGE
This cross-sectional micro-epidemiological study maps household locations and assesses the prevalence and intensity of Schistosoma mansoni and hookworm infections among primary-school children in a single village in western Côte d'Ivoire, finding random small-scale spatial distr…
DOI: 10.1645/GE-75R -
Nurture thru Nature: Creating natural science identities in populations of disadvantaged children through community education partnership
Nurture thru Nature (NtN), a natural science after-school and summer program, shows promise in improving science and language arts grades in disadvantaged elementary school students, but math improvements were not statistically significant.
DOI: 10.1080/00958964.2017.1357524 -
Impact of free summer day camp on physical activity behaviors and screentime of elementary-age children from low-income households: a randomized clinical trial
Providing free community summer day camps to children from low-income households increased MVPA and decreased sedentary time and screen use during summer compared with summer as usual.
DOI: 10.1186/s12966-025-01852-2