Key messages
We found that prebiotics may not differ from placebo in preventing relapses of ulcerative colitis. For adults in remission, prebiotics may result in more side effects than placebo.
The evidence was of poor quality for remission, improvement in disease activity, inflammation, and quality of life, therefore we could not reach any conclusions for these outcomes.
There needs to be more high-quality research on this topic before any firm conclusions can be reached.
What is ulcerative colitis?
Ulcerative colitis is one of the two main forms of inflammatory bowel disease. It is a lifelong condition that causes inflammation and ulcers in the large bowel. Symptoms include bloody stools, diarrhoea, stomach pain, fever, weight loss, and feeling tired. We don't know exactly what causes ulcerative colitis. It is probably a mix of genes, immune system problems, bacteria in the gut, and something in the environment. There is no known cure, but the symptoms are usually managed with medicine and sometimes surgery.
Most people with ulcerative colitis have times when they have symptoms (active disease) and times when their symptoms are under control (remission). When symptoms come back after being in remission, it is called relapse. When medicines are used to get ulcerative colitis under control, it is called induction of remission. When medicines are used to keep ulcerative colitis under control, it is called maintenance of remission.
What did we want to find out?
We wanted to find out if prebiotics work and are safe for the treatment of ulcerative colitis. Prebiotics are foods that affect the balance of good and bad bacteria in your gut.
We wanted to find out if prebiotics can get active ulcerative colitis into remission, prevent relapses, and improve disease activity, inflammation, and quality of life. We also wanted to find out how many people have side effects from prebiotics, and how many people stop taking prebiotics because of side effects.
What did we do?
We searched for randomised controlled trials (studies where people are assigned to one of two or more treatment groups using a random method) comparing prebiotics with any other treatment, standard treatment, dummy treatment (placebo), or different dosages of prebiotics.
What did we find?
We found 9 studies involving a total of 445 people with ulcerative colitis. The studies lasted from 14 days to 6 months. Five studies included people with active disease; three included people in remission; and one study did not report this information. In most studies, people continued taking their usual ulcerative colitis medicines.
Two studies compared prebiotics with dummy treatment for induction of remission. There was no information on rate of side effects. We do not know if prebiotics affect any of the other outcomes we looked at because the quality of the evidence was very low.
Two studies compared different doses of prebiotics for induction of remission. We do not know if prebiotics affect any of the outcomes we looked at because the quality of the evidence was very low.
One study compared prebiotics plus anti-inflammatory therapy with anti-inflammatory therapy alone for induction of remission. There was no information on remission, quality of life, side effects, or rate of withdrawals due to side effects. We do not know if prebiotics affect any of the other outcomes we looked at because the quality of the evidence was very low.
Three studies compared prebiotics with dummy treatment for maintenance of remission. There may be no difference in rate of relapse between prebiotics and dummy treatment. Prebiotics may lead to more side effects than dummy treatment. We do not know if prebiotics affect any of the other outcomes we looked at because the quality of the evidence was very low.
One study compared prebiotics with prebiotics plus probiotics for maintenance of remission. There was no information on relapse, disease activity, inflammation, or rate of side effects. We do not know if prebiotics affect any of the other outcomes we looked at because the quality of the evidence was very low.
One study compared prebiotics with probiotics for maintenance of remission. There was no information on relapse, disease activity, inflammation, or rate of side effects. We do not know if prebiotics affect any of the other outcomes we looked at because the quality of the evidence was very low.
What are the limitations of the evidence?
The evidence is mostly of very low and low quality. This is because of problems with the way the studies were performed and how results were reported. Additionally, there very small numbers of people included for most of the outcomes we examined.
How up-to-date is this review?
This review is current to June 2023.
There may be no difference in occurrence of clinical relapse when adjuvant treatment with prebiotics is compared with adjuvant treatment with placebo for maintenance of remission in UC. Adjuvant treatment with prebiotics may result in more total adverse events when compared to adjuvant treatment with placebo for maintenance of remission. We could draw no conclusions for any of the other outcomes in this comparison due to the very low certainty of the evidence. The evidence for all other comparisons and outcomes was also of very low certainty, precluding any conclusions.
It is difficult to make any clear recommendations for future research based on the findings of this review given the clinical and methodological heterogeneity among studies. It is recommended that a consensus is reached on these issues prior to any further research.
People affected by ulcerative colitis (UC) are interested in dietary therapies as treatments that can improve their health and quality of life. Prebiotics are a category of food ingredients theorised to have health benefits for the gastrointestinal system through their effect on the growth and activity of intestinal bacteria and probiotics.
To assess the efficacy and safety of prebiotics for the induction and maintenance of remission in people with active UC.
We searched CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and WHO ICTRP on 24 June 2023.
We included randomised controlled trials (RCTs) on people with UC. We considered any type of standalone or combination prebiotic intervention, except those prebiotics combined with probiotics (known as synbiotics), compared to any control intervention. We considered interventions of any dose and duration.
We followed standard Cochrane methodology.
We included 9 RCTs involving a total of 445 participants. Study duration ranged from 14 days to 2 to 3 months for induction and 1 to 6 months for maintenance of remission. All studies were on adults. Five studies were on people with mild to moderate active disease, three in remission or mild activity, and one did not mention.
We judged only one study as at low risk of bias in all areas.
Two studies compared prebiotics with placebo for induction of remission. We cannot draw any conclusions about clinical remission (70% versus 67%; risk ratio (RR) 1.05, 95% confidence interval (CI) 0.57 to 1.94); clinical improvement (mean Rachmilewitz score on day 14 of 4.1 versus 4.5; mean difference (MD) −0.40, 95% CI −2.67 to 1.87); faecal calprotectin levels (mean faecal calprotectin on day 14 of 1211 μg/mL versus 3740 μg/mL; MD −2529.00, 95% CI −6925.38 to 1867.38); interleukin-8 (IL-8) levels (mean IL-8 on day 7 of 2.9 pg/mL versus 5.0 pg/mL; MD −2.10, 95% CI −4.93 to 0.73); prostaglandin E2 (PGE-2) levels (mean PGE-2 on day 7 of 7.1 ng/mL versus 11.5 ng/mL; MD −4.40, 95% CI −20.25 to 11.45); or withdrawals due to adverse events (21% versus 8%; RR 2.73, 95% CI 0.51 to 14.55). All evidence was of very low certainty. No other outcomes were reported.
Two studies compared inulin and oligofructose 15 g with inulin and oligofructose 7.5 g for induction of remission. We cannot draw any conclusions about clinical remission (53% versus 12.5%; RR 4.27, 95% CI 1.07 to 16.96); clinical improvement (67% versus 25%; RR 2.67, 95% CI 1.06 to 6.70); total adverse events (53.5% versus 31%; RR 1.71, 95% CI 0.72 to 4.06); or withdrawals due to adverse events (13% versus 25%; RR 0.53, 95% CI 0.11 to 2.50). All evidence was of very low certainty. No other outcomes were reported.
One study compared prebiotics and anti-inflammatory therapy with anti-inflammatory therapy alone for induction of remission. We cannot draw any conclusions about clinical improvement (mean Lichtiger score at 4 weeks of 6.2 versus 10.3; MD −4.10, 95% CI −8.14 to −0.06) or serum C-reactive protein (CRP) levels (mean CRP levels at 4 weeks 0.55 ng/mL versus 0.50 ng/mL; MD 0.05, 95% CI −0.37 to 0.47). All evidence was of very low certainty. No other outcomes were reported.
Three studies compared prebiotics with placebo for maintenance of remission. There may be no difference between groups in rate of clinical relapse (44% versus 33%; RR 1.36, 95% CI 0.79 to 2.31), and prebiotics may lead to more total adverse events than placebo (77% versus 46%; RR 1.68, 95% CI 1.18 to 2.40). The evidence was of low certainty. We cannot draw any conclusions about clinical improvement (mean partial Mayo score at day 60 of 0.428 versus 1.625; MD −1.20, 95% CI −2.17 to −0.22); faecal calprotectin levels (mean faecal calprotectin level at day 60 of 214 μg/mL versus 304 μg/mL; MD −89.79, 95% CI −221.30 to 41.72); quality of life (mean Inflammatory Bowel Disease Questionnaire (IBDQ) score at day 60 of 193.5 versus 188.0; MD 5.50, 95% CI −8.94 to 19.94); or withdrawals due to adverse events (28.5% versus 11%; RR 2.57, 95% CI 1.15 to 5.73). The evidence for these outcomes was of very low certainty. No other outcomes were reported.
One study compared prebiotics with synbiotics for maintenance of remission. We cannot draw any conclusions about quality of life (mean IBDQ score at 4 weeks 182.4 versus 176.1; MD 6.30, 95% CI −6.61 to 19.21) or withdrawals due to adverse events (23% versus 20%; RR 1.13, 95% CI 0.48 to 2.62). All evidence was of very low certainty. No other outcomes were reported.
One study compared prebiotics with probiotics for maintenance of remission. We cannot draw any conclusions about quality of life (mean IBDQ score at 4 weeks 182.4 versus 168.6; MD 13.60, 95% CI 1.22 to 25.98) or withdrawals due to adverse events (22.5% versus 22.5%; RR 1.00, 95% CI 0.44 to 2.26). All evidence was of very low certainty. No other outcomes were reported.