Are non-absorbable disaccharides associated with beneficial or harmful effects in people with cirrhosis and hepatic encephalopathy?


Cirrhosis is a chronic disorder of the liver. People with cirrhosis may develop hepatic encephalopathy, a condition that results in poor brain functioning. Hepatic encephalopathy may be clinically obvious (overt) with changes including poor concentration, tremor, and alterations in consciousness. Others have no obvious clinical changes (minimal) but, when tested, some aspects of brain function such as attention and the ability to perform complex tasks are impaired.

The reason why people develop hepatic encephalopathy is complex. The accumulation of ammonia plays a key role. The non-absorbable disaccharides, lactulose and lactitol, are indigestible sugars that reduce the levels of ammonia in the blood.

Review question

We investigated the use of non-absorbable disaccharides for the prevention and treatment of hepatic encephalopathy in people with cirrhosis by reviewing randomised clinical trials (RCTs).

Search date

The search date was October 2015.

Study funding sources

Seven RCTs received financial support and 11 RCTs received lactitol or inactive placebo free of charge from a pharmaceutical company.

Study characteristics

We included 29 RCTs comparing non-absorbable disaccharides with inactive placebo or no intervention and nine RCTs comparing lactulose with lactitol. Seven of the included RCTs evaluated the prevention of hepatic encephalopathy and 31 evaluated the treatment of hepatic encephalopathy. Sixteen of the treatment RCTs included people with overt hepatic encephalopathy while 15 included people with minimal hepatic encephalopathy. The duration of treatment varied depending on the type of hepatic encephalopathy from five days to one year.

Key results

People who received non-absorbable disaccharides were less likely to die than people given a placebo or no treatment. They were also less likely to develop serious complications of their liver disease such as liver failure, bleeding, and infections. The non-absorbable disaccharides were also effective in preventing the development of hepatic encephalopathy and increased the number of participants who recovered from hepatic encephalopathy. There was some evidence from a small number of trials that lactulose has a beneficial effect on the quality of life, but we were unable to include the data in an overall analysis. The non-absorbable disaccharides were associated with adverse events including diarrhoea, nausea, bloating, and flatulence. None of the RCTs comparing lactulose versus lactitol reported quality of life. The analyses showed no differences between the two interventions for the remaining outcomes.

Quality of the evidence

In the comparison of non-absorbable disaccharides versus placebo/no intervention, we found moderate quality evidence of benefit for the outcomes of death, hepatic encephalopathy, and serious complications. The evidence for the remaining outcomes was of very low quality.

Authors' conclusions: 

This review includes a large number of RCTs evaluating the prevention or treatment of hepatic encephalopathy. The analyses found evidence that non-absorbable disaccharides may be associated with a beneficial effect on clinically relevant outcomes compared with placebo/no intervention.

Read the full abstract...

Non-absorbable disaccharides (lactulose and lactitol) are recommended as first-line treatment for hepatic encephalopathy. The previous (second) version of this review included 10 randomised clinical trials (RCTs) evaluating non-absorbable disaccharides versus placebo/no intervention and eight RCTs evaluating lactulose versus lactitol for people with cirrhosis and hepatic encephalopathy. The review found no evidence to either support or refute the use of the non-absorbable disaccharides and no differences between lactulose versus lactitol.


To assess the beneficial and harmful effects of i) non-absorbable disaccharides versus placebo/no intervention and ii) lactulose versus lactitol in people with cirrhosis and hepatic encephalopathy.

Search strategy: 

We carried out electronic searches of the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 10), MEDLINE, EMBASE, and Science Citation Index Expanded to 19 October 2015; manual searches of meetings and conference proceedings; checks of bibliographies; and correspondence with investigators and pharmaceutical companies.

Selection criteria: 

We included RCTs, irrespective of publication status, language, or blinding.

Data collection and analysis: 

Two review authors, working independently, retrieved data from published reports and correspondence with investigators. The primary outcomes were mortality, hepatic encephalopathy, and serious adverse events. We presented the results of meta-analyses as risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI). We assessed the quality of the evidence using 'Grading of Recommendations Assessment Development and Evaluation' (GRADE) and bias control using the Cochrane Hepato-Biliary Group domains. Our analyses included regression analyses of publication bias and other small study effects, Trial Sequential Analyses to detect type 1 and type 2 errors, and subgroup and sensitivity analyses.

Main results: 

We included 38 RCTs with a total of 1828 participants. Eight RCTs had a low risk of bias in the assessment of mortality. All trials had a high risk of bias in the assessment of the remaining outcomes. Random-effects meta-analysis showed a beneficial effect of non-absorbable disaccharides versus placebo/no intervention on mortality when including all RCTs with extractable data (RR 0.59, 95% CI 0.40 to 0.87; 1487 participants; 24 RCTs; I2 = 0%; moderate quality evidence) and in the eight RCTs with a low risk of bias (RR 0.63, 95% CI 0.41 to 0.97; 705 participants). The Trial Sequential Analysis with the relative risk reduction (RRR) reduced to 30% confirmed the findings when including all RCTs, but not when including only RCTs with a low risk of bias or when we reduced the RRR to 22%. Compared with placebo/no intervention, the non-absorbable disaccharides were associated with beneficial effects on hepatic encephalopathy (RR 0.58, 95% CI 0.50 to 0.69; 1415 participants; 22 RCTs; I2 = 32%; moderate quality evidence). Additional analyses showed that non-absorbable disaccharides can help to reduce serious adverse events associated with the underlying liver disease including liver failure, hepatorenal syndrome, and variceal bleeding (RR 0.47, 95% CI 0.36 to 0.60; 1487 participants; 24 RCTs; I2 = 0%; moderate quality evidence). We confirmed the results in Trial Sequential Analysis. Tests for subgroup differences showed no statistical differences between RCTs evaluating prevention, overt, or minimal hepatic encephalopathy. The evaluation of secondary outcomes showed a potential beneficial effect of the non-absorbable disaccharides on quality of life, but we were not able to include the data in an overall meta-analysis (very low quality evidence). Non-absorbable disaccharides were associated with non-serious (mainly gastrointestinal) adverse events (very low quality evidence). None of the RCTs comparing lactulose versus lactitol evaluated quality of life. The review found no differences between lactulose and lactitol for the remaining outcomes (very low quality evidence).