Diarrhea
Supplements studied for diarrhea.
Overview
Zinc has the strongest evidence (WA 76, five studies): 5–20 mg daily shortens diarrhea duration in malnourished or zinc-deficient children by roughly 11–26 hours and lowers persistence rates. Saccharomyces boulardii (WA 68; medium effect size, very high evidence, medium trust; 15 studies) may shorten acute diarrhea by about one day in children and works well combined with zinc.
Probiotics (WA 64; medium effect size, medium evidence, high trust) are possibly effective per limited trials. Vitamin A (WA 60) reduces diarrhea incidence and mortality in young children when supplemented directly, though maternal supplementation did not clearly help breastfed infants. Nattokinase entries reflect soy formula/fiber research rather than nattokinase itself. See the heatmap and evidence reviews below.
Effect graph
Relevant supplements
Relevant supplements sorted by DEX Score.
| Zinc | ★★★★★ | High |
| Saccharomyces boulardii | ★★★★★ | Medium |
| Nattokinase | ★★★★★ | Medium |
| Probiotics | ★★★★★ | Medium |
| Boswellia | ★★★★★ | Low |
| Black Tea | ★★★★★ | Low |
| Oleic Acid | ★★★★★ | Low |
| Vitamin B9 (Folate) | ★★★★★ | Very Low / None |
Studies
Find individual evidence reviews for supplements sorted by DEX Score.
8 supplements for , and rated at least stars. All purchase bands. No minimum star filter.
ZincView supplement →
Consider purchase·★★★★★
How we scored this▸
- Zinc helps shorten and lessen the severity of diarrhea in children who are malnourished or have low zinc levels.
- Studies show that zinc can reduce how long diarrhea lasts—on average by about 11 hours for short-term diarrhea and about 16 hours for ongoing cases.
- The biggest benefits are seen in children who are clearly undernourished, where zinc can shorten symptoms by about 26 hours and lower the chance of diarrhea continuing on days 3, 5, and 7 by 18–24%.
- Taking 5–20 mg of zinc per day works well.
- Smaller doses of 5–10 mg are less likely to cause vomiting than 20 mg and work just as effectively.
- The type of zinc—sulfate, gluconate, or acetate—doesn’t seem to matter.
- Zinc might also lower the risk of death from diarrhea in children under five by about 15%, but the evidence isn’t strong enough to be certain.
Browse 5 studies·2 meta-analyses
MetaEffect of zinc supplementation on mortality in under 5-year children: a systematic review and meta-analysis of randomized clinical trials2021n=237,068
A meta-analysis of 28 RCTs in 237,068 under-5 children found zinc supplementation reduced all-cause mortality by 16%, with stronger reductions at ≥10 mg/day and in low-birth-weight infants.
- Effect
- No Benefit
- Duration
- 11 months
- Dose
- 10 mg/day
- Population
- Children/adolescents
- Participants
- 237,068
- Ages
- under 5
RCTLower-Dose Zinc for Childhood Diarrhea - A Randomized, Multicenter Trial2020n=4,500
In 4,500 children aged 6–59 months with acute diarrhea, 5 mg and 10 mg/day zinc for 14 days were noninferior to 20 mg/day for diarrhea duration and stool count but caused significantly less vomiting.
- Effect
- Benefit
- Duration
- 14 days
- Dose
- 20 mg
- Population
- Children/adolescents
- Participants
- 4,500
- Ages
- 6–59 months
MetaOral zinc for treating diarrhoea in children2016n=10,841
A Cochrane review of 33 trials in 10,841 children found zinc shortened acute diarrhea by about half a day in children over 6 months and by about one day in malnourished children, with increased vomiting risk.
- Effect
- Benefit
- Duration
- 6 months
- Population
- Children/adolescents
- Participants
- 10,841
- Ages
- 1–59 months
MetaWhat zinc supplementation does and does not achieve in diarrhea prevention: a systematic review and meta-analysis2011
A meta-analysis found preventive zinc associated with modest reductions in diarrhea incidence (9%), prevalence (19%), and multiple episodes (28%), but evidence for persistent diarrhea, dysentery, and mortality was inconclusive.
- Effect
- No Benefit
- Population
- Children
MetaZinc for the treatment of diarrhoea: effect on diarrhoea morbidity, mortality and incidence of future episodes2010
A systematic review of 13 treatment trials concluded zinc for childhood diarrhea reduces episodes lasting beyond 7 days, hospitalizations, and estimated diarrhea mortality by about 23%.
- Effect
- Benefit
- Dose
- 40 mg/day
- Population
- Children/adolescents
- Ages
- 1–59 months
NattokinaseView supplement →
Consider purchase·★★★★★
How we scored this▸
- Soy-based formulas and soy fiber have been shown in studies to help shorten and ease acute diarrhea in young children and in some other settings.
- Most research has used soy formula or soy fiber in the diet, not nattokinase supplements.
- If your child has diarrhea, ask your doctor about the best feeding approach.
Browse 10 studies
RCTUse of soy fiber in acute diarrhea in infants and toddlers1997n=44
In 44 US infants >6 months with acute diarrhea, soy fiber-supplemented formula (Isomil DF) shortened median diarrhea duration to 9.7 hours vs 23.1 hours with standard soy formula.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 44
RCTCow's milk versus soy-based formula in mild and moderate diarrhea: a randomized, controlled trial1994n=76
In 73 infants aged 2–12 months with mild or moderate diarrhea, soy-based formula refeeding after rehydration did not differ from cow's milk formula in time to first normal stool.
- Effect
- No Benefit
- Duration
- 2–12 months
- Population
- Children/adolescents
- Participants
- 76
- Ages
- 2–12
RCTEffect of dietary fiber (soy polysaccharide) on the severity, duration, and nutritional outcome of acute, watery diarrhea in children1993n=19
In 34 Peruvian infants with acute watery diarrhea, adding soy polysaccharide to soy formula did not reduce stool output or duration vs soy formula without fiber.
- Effect
- No Benefit
- Population
- Children/adolescents
- Participants
- 19
RCTRole of a soy-based lactose-free formula in the outpatient management of diarrhea1991
In 56 outpatient infants with diarrhea, early introduction of soy lactose-free formula resolved diarrhea in 72% by 48 h vs 44% with oral rehydration alone for 24 h (P = 0.02).
- Effect
- Benefit
- Population
- Children/adolescents
RCTSoy-polysaccharide fiber: effect on diarrhea in tube-fed, head-injured patients1989
In 9 head-injured tube-fed patients, soy polysaccharide fiber did not reduce stool weight, improve consistency, or lower diarrhea incidence vs fiber-free feeding.
- Effect
- No Benefit
- Population
- Head-injured patients
RCTThe effect of feeding four different formulae on stool weights in prolonged dehydrating infantile gastroenteritis1988
In 72 South African infants with prolonged dehydrating gastroenteritis, stool weights were similar across cow's milk, lactose-free casein, soy, and whey-hydrolysate formulas over 3 days.
- Effect
- No Benefit
- Duration
- 3 days
- Dose
- 30 g/kg
- Population
- Children/adolescents
- Ages
- 6 weeks–2 years
RCTRole of soy-based, lactose-free formula during treatment of acute diarrhea1985n=44
In 87 American Indian infants with acute diarrhea, early soy lactose-free feeding reduced stool output (121 vs 299 mL/kg) and illness duration (54 vs 93 h) vs 48-h dietary restriction.
- Effect
- Benefit
- Population
- Infants
- Participants
- 44
RCTDietary treatment of acute diarrhea: comparison between cow's milk and a soy formula without disaccharides1984
In a randomized trial comparing cow's milk and soy formula without disaccharides for acute infantile diarrhea, both formulas were evaluated but detailed outcome data were not reported in the available abstract.
- Population
- Children/adolescents
Controlled trialThe use of a soy isolate based formula in the treatment of infantile diarrhoea1981n=112
In 112 infants with severe diarrhoea requiring IV rehydration, lactose-free soy isolate formula (Isomil) had a 93% response rate vs 75% with standard cow's milk formula.
- Effect
- Benefit
- Population
- Infants
- Participants
- 112
Clinical trialSoy-based formula for infantile diarrhoea: a controlled trial1979
In a controlled trial of soy-based formula for infantile diarrhoea, limited abstract data were available to assess comparative efficacy vs standard formula.
- Effect
- Benefit
Saccharomyces boulardiiView supplement →
Consider purchase·★★★★★
How we scored this▸
- Taking Saccharomyces boulardii can help children with acute diarrhea get better about one day faster and may shorten hospital stays by about a day.
- It works well when given with zinc, with the combination helping kids recover even faster.
- Studies show it lowers how often kids have diarrhea stools and helps them return to normal stools sooner, especially for common stomach viruses.
- Saccharomyces boulardii may also help with longer-lasting diarrhea in young children.
- For adults, the benefits are less clear.
- In very sick adults on feeding tubes, it may reduce diarrhea.
- Overall, S. boulardii is safe and helpful for managing diarrhea in children.
Browse 15 studies·4 meta-analyses
MetaEffectiveness and Safety of Saccharomyces Boulardii for the Treatment of Acute Gastroenteritis in the Pediatric Population: A Systematic Review and Meta-Analysis of Randomized Controlled Trials2022n=1,282
A meta-analysis found S. boulardii reduced acute gastroenteritis duration and stool frequency in children under 5 versus control.
- Effect
- Benefit
- Duration
- 1 day
- Population
- Children/adolescents
- Participants
- 1,282
- Ages
- <5
RCTComparison of safety, effectiveness and serum inflammatory factor indexes of Saccharomyces boulardii versus Bifidobacterium triple viable in treating children with chronic diarrhea: a randomized trial2021n=161
In 161 children with chronic diarrhea, S. boulardii improved recovery rate and safety profile versus bifidobacterium triple viable.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 161
- Ages
- 2–8
RCTEffect of Saccharomyces boulardii CNCM-I 3799 and Bacillus subtilis CU-1 on Acute Watery Diarrhea: A Randomized Double-Blind Placebo-Controlled Study in Indian Children2021n=180
In 180 children with acute diarrhea, combined S. boulardii and B. subtilis with ORS and zinc improved recovery versus placebo.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 180
MetaWhich Probiotic Is the Most Effective for Treating Acute Diarrhea in Children? A Bayesian Network Meta-Analysis of Randomized Controlled Trials2021n=13,443
A network meta-analysis found S. boulardii among the more effective probiotics for shortening acute diarrhea in children.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 13,443
RCTA Multicenter, Randomized, Double-blind, Placebo-controlled Trial of Saccharomyces boulardii in Infants and Children With Acute Diarrhea2020n=100
In 100 infants with acute diarrhea, S. boulardii CNCM I-3799 5 billion CFU twice daily improved recovery versus placebo over 5 days.
- Effect
- Benefit
- Duration
- 5 days
- Dose
- 10^10 CFU/day S. boulardii
- Population
- Children/adolescents
- Participants
- 100
- Ages
- 3–36 months
MetaSystematic review with meta-analysis: Saccharomyces boulardii for treating acute gastroenteritis in children-a 2020 update2020n=3,450
A meta-analysis found S. boulardii shortened acute gastroenteritis in children versus no treatment or placebo.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 3,450
RCTClinical Efficacy Comparison of Saccharomyces Boulardii and Lactic Acid as Probiotics in Acute Pediatric Diarrhea2018
In children with acute diarrhea, S. boulardii and lactic acid probiotics both shortened illness versus usual care, with similar efficacy.
- Effect
- Benefit
- Duration
- 5 days
- Population
- Children/adolescents
- Ages
- 6 months–5 years
MetaComparative effectiveness and safety of interventions for acute diarrhea and gastroenteritis in children: A systematic review and network meta-analysis2018
A comparative effectiveness review found zinc, probiotics including S. boulardii, and some antidiarrheals shorten acute diarrhea in children.
- Effect
- Benefit
- Population
- Children/adolescents
RCTComparison of Two Forms of Loperamide-Simeticone and a Probiotic Yeast (Saccharomyces boulardii) in the Treatment of Acute Diarrhoea in Adults: A Randomised Non-Inferiority Clinical Trial2015n=139
In adults with acute diarrhea, loperamide-simeticone and S. boulardii both improved symptoms versus placebo, with similar tolerability.
- Effect
- Benefit
- Duration
- 5 days
- Dose
- 250 mg 2×/day
- Population
- Adults
- Participants
- 139
- Ages
- 18+
RCTSaccharomyces boulardii CNCM I-745 reduces the duration of diarrhoea, length of emergency care and hospital stay in children with acute diarrhoea2015n=363
In children with acute watery diarrhea, S. boulardii CNCM I-745 reduced duration of diarrhea and hospital stay versus standard care.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 363
MetaEfficacy and safety of Saccharomyces boulardii for acute diarrhea2014
A systematic review found S. boulardii effective and safe for acute childhood diarrhea, though trial quality varied.
- Effect
- Benefit
- Population
- Children/adolescents
RCTEfficacy and safety of Saccharomyces boulardii in acute childhood diarrhea: a double blind randomised controlled trial2012
In children aged 3 months to 5 years, S. boulardii 250 mg twice daily for 5 days shortened diarrhea duration versus placebo.
- Effect
- Benefit
- Duration
- 5 days
- Dose
- 250 mg 2×/day
- Population
- Children/adolescents
- Ages
- 3–59 mo
RCTEffects of Saccharomyces boulardii in children with acute diarrhoea2005n=200
In 200 children with acute diarrhoea, S. boulardii 250 mg for 5 days reduced stool frequency faster than placebo after day 2.
- Effect
- Benefit
- Duration
- 5 days
- Dose
- 250 mg/day
- Population
- Children/adolescents
- Participants
- 200
RCTEffect of Lactobacillus strains and Saccharomyces boulardii on persistent diarrhea in children2003n=30
In 89 children with persistent diarrhea, Lactobacillus or S. boulardii shortened illness versus placebo.
- Effect
- Benefit
- Duration
- 5 days
- Dose
- 175 g 2×/day
- Population
- Children/adolescents
- Participants
- 30
- Ages
- 6–24
RCTSaccharomyces boulardii prevents diarrhea in critically ill tube-fed patients. A multicenter, randomized, double-blind placebo-controlled trial1997n=128
In tube-fed ICU patients, S. boulardii 500 mg four times daily did not significantly reduce diarrhea incidence versus placebo.
- Effect
- No Benefit
- Dose
- 2000 mg/day
- Population
- Head-injured patients
- Participants
- 128
ProbioticsView supplement →
Consider purchase·★★★★★
How we scored this▸
- Probiotics are possibly effective for Diarrhea.
Browse 2 studies·1 meta-analysis
RCTEfficacy and Safety of Lactobacillus acidophilus LA85 in Preventing Antibiotic-Associated Diarrhea: A Randomized, Placebo-Controlled Study2025n=82
In 82 adults on amoxicillin, Lactobacillus acidophilus LA85 2×10^9 CFU/day for 14 days shortened diarrhea duration versus placebo, though AAD incidence reduction was not significant.
- Effect
- Benefit
- Duration
- 14 days
- Population
- Adults
- Participants
- 82
MetaEfficacy and safety of Saccharomyces boulardii CNCM I-745 for the treatment of pediatric acute diarrhea in China: a systematic review and meta-analysis2025n=1,125
A meta-analysis of 10 Chinese pediatric trials (n=1125) found Saccharomyces boulardii CNCM I-745 shortened acute diarrhea duration and raised treatment effectiveness versus control.
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 1,125
- Ages
- <5
Black TeaView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Black tea might help improve stool consistency in children with acute nonbacterial diarrhea.
- One early study found that giving children a single dose of black tea tablets dissolved in water improved stool consistency within a day compared to placebo.
Browse 1 study
RCTThe Effect of Black Tea (Camellia sinensis (L) Kuntze) on Pediatrics With Acute Nonbacterial Diarrhea: A Randomized Controlled Trial2017n=120
In 120 children with acute nonbacterial diarrhea, black tea tablets plus standard treatment increased the proportion with formed stool after 24 h and reduced defecation frequency versus standard treatment alone.
- Effect
- Benefit
- Dose
- 2 g/day
- Population
- Children/adolescents
- Participants
- 120
BoswelliaView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is unclear if taking Boswellia serrata helps with acute diarrhea.
- A small study found that taking a special form of Boswellia extract twice daily for five days shortened diarrhea by about 1.4 days, reduced how often people had diarrhea, and improved stomach pain and nausea better than a placebo.
Browse 1 study
RCTPositive Effects of a Lecithin-Based Delivery Form of Boswellia serrata Extract in Acute Diarrhea of Adult Subjects2022n=49
In 49 adults with acute diarrhea, 250 mg/day lecithin-based Boswellia serrata extract (CASP) for 5 days shortened time to recovery (3.08 vs 4.44 days; p<0.0001) and reduced stool frequency, abdominal pain, and nausea.
- Effect
- Benefit
- Duration
- 5 days
- Dose
- 250 mg/day
- Population
- Adults
- Participants
- 49
Oleic AcidView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is unclear if taking oleic acid helps with chronic diarrhea.
- A small study found that taking oleic acid before meals reduced bowel movements by about 22% during the day and slowed digestion time by about half an hour to nearly an hour.
- Since the reasons for diarrhea were different in the patients studied, it’s not clear if oleic acid helps all types of chronic diarrhea or only some types.
Browse 1 study
Controlled trialSlowing of gastrointestinal transit by oleic acid: a preliminary report of a novel, nutrient-based treatment in humans2001n=45
In 45 patients with chronic diarrhea, pre-meal oleic acid emulsion dose-dependently slowed gastrointestinal transit (29 to 83 min) and reduced stool frequency and volume.
- Effect
- Benefit
- Dose
- 1.6–3.2 ml oleic acid
- Population
- Patients with chronic diarrhea
- Participants
- 45
Vitamin B9 (Folate)View supplement →
Do not purchase·★★★★★
How we scored this▸
- Giving folic acid, with or without vitamin B12, to young children at risk of malnutrition for 6 months does not lower the chance of getting diarrhea compared to a placebo.
- In fact, it may increase the risk of longer-lasting diarrhea.
Browse 1 study
RCTFolic acid and vitamin B-12 supplementation and common infections in 6-30-mo-old children in India: a randomized placebo-controlled trial2013
A randomized trial in children/adolescents found that in comparison with placebo, children treated with folic acid alone or in combination with vitamin B-12 had a significantly higher risk of persistent diarrhea (OR: 2.1; 95% CI: 1.1, 3.8).
- Effect
- No Benefit
- Duration
- 6–30 months
- Population
- Children/adolescents
- Ages
- 6–30
Evidence visualised
Same ratings as above, aggregated so you can see coverage and imbalance.
| Supplement | DEX | Studies | Meta-analyses | Share |
|---|---|---|---|---|
| Saccharomyces boulardii | ★★★★★68% | 15 | 4 | 42% |
| Nattokinase | ★★★★★68% | 10 | 0 | 28% |
| Zinc | ★★★★★76% | 5 | 2 | 14% |
| Probiotics | ★★★★★64% | 2 | 1 | 6% |
| Black Tea | ★★★★★44% | 1 | 0 | 3% |
| Boswellia | ★★★★★44% | 1 | 0 | 3% |
| Oleic Acid | ★★★★★40% | 1 | 0 | 3% |
| Vitamin B9 (Folate) | ★★★★★32% | 1 | 0 | 3% |