Question explored with the scientific record
Conversation so far
- 1 what supplements help children prevent ARIs + a private exchange
- 2 so any evidence for any supplement for prevention in children
Answered on this page ↓
so any evidence for any supplement for prevention in children
The short version: vitamin D and probiotics have the best evidence for preventing respiratory and diarrheal infections in children, but the effect is modest and dose-dependent.
The 2025 meta-analysis of 17 pediatric trials (18,372 children) found that vitamin D supplementation did not reduce overall ARI incidence (RR 0.82, p=0.13) [4]. But daily low doses (≤1000 IU/day) did cut risk by about 58% (RR 0.42, p<0.001), while higher doses showed no effect [4]. The same analysis found vitamin D lowered serious adverse events (RR 0.83, p=0.015) with no mortality benefit [4]. This pattern matches the colloidal frame: low-dose daily vitamin D supports zeta potential and immune regulation without overwhelming the system.
For probiotics, the 2025 umbrella meta-analysis of 35 pediatric reviews found probiotics reduced diarrhea incidence by about half (OR 0.47) and shortened duration by nearly two days [15]. The effect was stronger with single-strain products than multi-strain [15]. A 2007 trial in infants found probiotics cut diarrhea duration from 73 to 49 hours [8]. The evidence for preventing respiratory infections specifically is weaker than for diarrhea.
Zinc also shows benefit. A 1998 review found zinc supplementation reduced diarrhea incidence by 35-45% in developing-country children [7]. A 2024 trial found adding zinc to probiotics shortened healing time from 2.0 to 1.3 days [13].
| Supplement | Best evidence | Effect size | Confidence |
|---|---|---|---|
| Vitamin D (≤1000 IU/day) | 2025 meta-analysis, 18,372 children [4] | 58% fewer ARIs | Moderate |
| Probiotics | 2025 umbrella meta-analysis, 35 reviews [15] | 53% fewer diarrhea episodes | Moderate |
| Zinc | 1998 review, multiple trials [7] | 35-45% fewer diarrhea episodes | Low-moderate |
My call: daily low-dose vitamin D (≤1000 IU) and a single-strain probiotic are the supplements with the best evidence for preventing infections in children, but the effects are modest and the evidence base is funded mostly by industry. Confidence: moderate for vitamin D at low doses, moderate for probiotics against diarrhea, low for respiratory prevention with probiotics.
Sources used 27
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Vitamin D insufficiency among hospitalised children in the N orthern T erritory
This study investigates the prevalence of vitamin D insufficiency among children hospitalized with acute lower respiratory infections (ALRIs) in the Northern Territory of Australia, finding that nearly one-third of the children were insufficient in vitamin D, with a notable diff…
DOI: 10.1111/jpc.12623 -
Cost-utility of vitamin D supplementation to prevent acute respiratory infections in children
This study conducts a Colombian, CHEERS-guided cost-utility analysis of vitamin D supplementation to prevent acute respiratory infections in children, using a decision-tree model over six months with local cost data and external ARI risk reductions, finding vitamin D to be cost-…
DOI: 10.1186/s12962-023-00433-z -
Association of Vitamin D Deficiency with Acute Lower Respiratory Infection in Toddlers
Hospital-based case–control study in Amritsar, India, showing that low 25(OH)D levels and severe vitamin D deficiency are associated with higher risk of acute lower respiratory infection in children aged 2 months to 5 years, while exclusive breastfeeding and longer sun exposure …
DOI: 10.3126/jnps.v36i1.13982 -
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 -
Vitamin D and Acute Respiratory Tract Infection
A comprehensive review summarizing evidence that low vitamin D status is associated with higher risk of acute respiratory tract infections (ARTI) in both developing and developed countries, and that vitamin D supplementation can reduce ARTI risk in certain populations, though re…
DOI: 10.2174/157339811798072586 -
Vitamin D Supplementation: A Potential Prevention Method against Contagious Viral Respiratory Illnesses
This narrative review synthesizes evidence from 12 articles (11 systematic reviews and meta-analyses and 1 randomized trial) to evaluate whether Vitamin D and its metabolites confer protection against contagious viral respiratory illnesses, including COVID-19, finding inverse as…
DOI: 10.47191/ijmra/v4-i10-25 -
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 -
Relation Between Dietary Essential Fatty Acid Intake and Dry Eye Disease and Meibomian Gland Dysfunction in Postmenopausal Women
This study investigates the relationship between dietary intake of omega-3 and omega-6 fatty acids and the prevalence of dry eye disease and meibomian gland dysfunction in postmenopausal women, finding no significant association with dry eye disease but a protective effect of hi…
DOI: 10.1016/j.ajo.2018.01.004 -
Efficacy of nutritional supplementation with omega‐3 and omega‐6 fatty acids in dry eye syndrome: a systematic review of randomized clinical trials
This systematic review evaluates the efficacy of nutritional supplementation with omega-3 and omega-6 fatty acids in treating dry eye syndrome, finding a modest improvement in tear function but insufficient evidence to recommend it as a standalone treatment.
DOI: 10.1111/aos.13428 -
P.100 Effect of the manipulation of dietary lipids uponthe fatty acid profile of different tissues in healthy rats
This study investigates the immune modulating effects of parenteral lipid emulsions with varying omega-3 to omega-6 fatty acid ratios on leukotriene synthesis in postoperative patients, revealing that higher omega-3 ratios may enhance leukotriene production.
DOI: 10.1016/s0261-5614(97)80224-5 -
Omega-3 fatty acid: A promising pathway linking personality and health
An editorial discussing how personality traits relate to plasma omega-3 fatty acids (omega-3 PUFA) in a large Dutch cohort, noting modest associations with higher neuroticism and lower conscientiousness/extraversion, and considering implications for health mechanisms and future …
DOI: 10.1016/j.jpsychores.2018.05.009 -
The combination of an antihistamine (chlorpheniramine) and an omega-3/omega-6 fatty acid-containing product for the management of pruritic cats: Results of an open clinical trial
This study evaluates the efficacy of a combination treatment of chlorpheniramine and an omega-3/omega-6 fatty acid supplement in managing pruritus in cats, finding that 54% of the cats exhibited excellent responses to the combination therapy after previously failing to respond t…
DOI: 10.1080/00480169.1995.35839 -
Dietary Intake of Specific Fatty Acids and Breast Cancer Risk Among Postmenopausal Women in the VITAL Cohort
This study investigates the association between dietary intake of specific fatty acids and breast cancer risk among postmenopausal women in the VITAL cohort, finding that higher intakes of total monounsaturated fatty acids and certain saturated fatty acids are linked to increase…
DOI: 10.1080/01635581.2012.718033 -
Comparative study between n-6, trans and n-3 fatty acids on repeated amphetamine exposure: A possible factor for the development of mania
This study investigates the effects of omega-6, trans, and omega-3 fatty acids on locomotor activity and oxidative stress in a rat model of mania induced by repeated amphetamine exposure, revealing that trans fatty acids exacerbate oxidative damage and behavioral hyperactivity.
DOI: 10.1016/j.pbb.2010.11.004 -
Lipid composition of indigenous foods eaten by the Sahtú (Hareskin) dene-metis of the Northwest territories
A nutrition-focused study analyzing the lipid content and fatty acid profiles of traditional Sahtti (Hareskin) Dene-Metis foods from two Northwest Territories communities, comparing indigenous foods to market foods and highlighting favorable polyunsaturated, especially omega-3, …
DOI: 10.1016/0889-1575(91)90004-p -
Decreasing dietary linoleic acid promotes long chain omega-3 fatty acid incorporation into rat retina and modifies gene expression
This study investigates the effects of decreasing dietary linoleic acid and increasing omega-3 fatty acids on their incorporation into the rat retina and the modulation of gene expression related to lipid metabolism, suggesting potential dietary strategies for preventing age-rel…
DOI: 10.1016/j.exer.2011.07.016