Lactulose
Research reviewed: Up until 03/2026
Lactulose (Lactulose (4-O-β-D-galactopyranosyl-D-fructose)) is a dietary supplement with 7 published peer-reviewed studies involving 406 participants, researched for Constipation, Hepatic Encephalopathy, Prebiotic & Microbiome Effects.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Constipation
ModerateHepatic Encephalopathy
ModeratePrebiotic & Microbiome Effects
ModerateResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Constipation
To evaluate lactulose for chronic constipation.
Study Type
Systematic review and meta-analysis
Purpose
To evaluate lactulose for chronic constipation.
Dose
15-30 mL/day (10-20 g)
Participants
Meta-analysis of 11 RCTs, 868 patients
Duration
2-12 weeks
Results
Lactulose significantly increased stool frequency (WMD 2.5 bowel movements/week) and improved stool consistency compared to placebo. NNT = 4.
How They Measured It
Stool frequency, stool consistency, straining, patient satisfaction
To evaluate lactulose for chronic constipation in elderly nursing home residents.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate lactulose for chronic constipation in elderly nursing home residents.
Dose
15 mL lactulose twice daily
Participants
115 elderly nursing home residents with chronic constipation
Duration
12 weeks
Results
Lactulose significantly increased bowel movement frequency and reduced need for rescue laxatives. 68% of patients reported satisfactory relief.
How They Measured It
Stool frequency, laxative use, stool consistency
To compare lactulose with PEG for chronic constipation in children.
Study Type
Randomised controlled trial
Purpose
To compare lactulose with PEG for chronic constipation in children.
Dose
Lactulose 1-2 mL/kg/day vs PEG 0.4 g/kg/day
Participants
100 children aged 2-14 with chronic constipation
Duration
8 weeks
Results
PEG was slightly more effective than lactulose for stool frequency, but both were effective. Lactulose was better tolerated with fewer taste complaints.
How They Measured It
Stool frequency, fecal incontinence episodes, abdominal pain
Hepatic Encephalopathy
To evaluate lactulose for prevention and treatment of hepatic encephalopathy.
Study Type
Systematic review and meta-analysis
Purpose
To evaluate lactulose for prevention and treatment of hepatic encephalopathy.
Dose
30-60 mL/day adjusted to produce 2-3 soft stools/day
Participants
Meta-analysis of 22 RCTs, 1415 patients with cirrhosis
Duration
Various (2 weeks to 12 months)
Results
Lactulose significantly reduced risk of hepatic encephalopathy (RR 0.47, 95% CI 0.37-0.60). Also showed reduction in mortality (RR 0.59) and improved cognitive function.
How They Measured It
Prevention of HE episodes, mortality, cognitive test scores
To evaluate lactulose for prevention of HE after acute variceal bleeding.
Study Type
Randomised controlled trial
Purpose
To evaluate lactulose for prevention of HE after acute variceal bleeding.
Dose
30-60 mL lactulose per day
Participants
70 cirrhotic patients with acute variceal bleeding
Duration
5 days
Results
Lactulose significantly reduced incidence of HE after variceal bleeding (14% vs 40% control). Blood ammonia was significantly lower in lactulose group.
How They Measured It
Incidence of hepatic encephalopathy, blood ammonia levels
Prebiotic & Microbiome Effects
To evaluate prebiotic effects of low-dose lactulose on gut microbiome.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate prebiotic effects of low-dose lactulose on gut microbiome.
Dose
5-10 g/day lactulose (sub-laxative dose)
Participants
48 healthy adults
Duration
4 weeks
Results
Sub-laxative doses of lactulose significantly increased fecal Bifidobacterium counts and SCFA (especially butyrate) production. Stool pH decreased.
How They Measured It
Fecal Bifidobacterium and Lactobacillus counts, SCFA levels, stool pH
To evaluate lactulose effects on gut microbiome in cirrhosis patients.
Study Type
Randomised controlled trial
Purpose
To evaluate lactulose effects on gut microbiome in cirrhosis patients.
Dose
30 mL/day lactulose
Participants
40 patients with compensated cirrhosis
Duration
8 weeks
Results
Lactulose shifted gut microbiome towards more beneficial composition (increased Bifidobacterium, decreased Enterobacteriaceae). Plasma endotoxin levels decreased.
How They Measured It
Fecal microbiome (16S rRNA), plasma endotoxin, systemic inflammation
Frequently Asked Questions
Common questions about Lactulose research
There are currently 7 peer-reviewed studies on Lactulose (Lactulose (4-O-β-D-galactopyranosyl-D-fructose)), involving 406 total participants. Research covers Constipation, Hepatic encephalopathy, Prebiotic effects and 1 more areas. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (5 human studies), and reported outcomes.
Lactulose has been researched for: Constipation, Hepatic encephalopathy, Prebiotic effects, Gut health. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 5 out of 7 studies are human trials. Human trials carry more weight in our evidence scoring system.
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