Prebiotics aren’t effective in active Crohn’s disease, researchers said here.

Different from probiotics, which are actual bacteria, these prebiotic carbohydrates enhance the presence of indigenous bacteria in the gut.

But in a randomized controlled trial, there was no difference in the number of patients who had a clinical response between those on prebiotics or those on placebo, James O. Lindsay, MD, of Barts and the London in the U.K., and colleagues presented during a poster session at Digestive Disease Week here.

“We didn’t see any differences, and there were more side effects with prebiotics,” Lindsay told MedPage Today. “[Prebiotics] are less effective in active disease.”

Research has shown that intestinal microbiota drive the inflammation associated with Crohn’s. So previous studies have looked at probiotics to see if these would alleviate the disease. But Lindsay said these studies were “generally all negative.”

Probiotics simply add bacteria into the gut that may not be native to a patient. So Lindsay and colleagues hypothesized that if Crohn’s patients were given prebiotics — which are essentially carbohydrates that induce changes in gut bacteria — their natural microflora would be enhanced.

They chose fructo-oligosaccharide, since preliminary data have shown that this carbohydrate can increase two types of colon bacteria — bifidobacteria and Faecalibacterium prausnitzii — and ultimately induce immunoregulatory dendritic cell responses.

Lindsay and his team had done earlier studies on the effects of this prebiotic, and found that it does increase the presence of certain bacteria.

So to assess the impact of a diet supplemented with prebiotics in patients with active Crohn’s, the researchers conducted a randomized, double-blind, placebo-controlled trial in 103 patients.

For four weeks, they received either 15g/day of fructo-oligosaccharide or an identical non-prebiotic maltodextrin placebo.

The primary endpoint was clinical response at week four, and secondary endpoints included disease remission and reduction in CRP and fecal calprotectin.

The researchers found no benefit of prebiotics over placebo. Lindsay said there was no difference between groups in the number of patients who had a clinical response to the treatment.

In fact, significantly more patients taking prebiotics withdrew from the study (26% versus 8%, P=0.018).

There were no differences in CRP or fecal calprotectin levels.

Yet there were some differences in immunological results. There was a significant increase in IL-10 production in patients on prebiotics, as well as a significant reduction in IL-6+, compared with those on placebo (P<0.05).

There was no effect on IL-12, but the other two findings may have something to do with the release of short-chain fatty acids induced by the prebiotic, Lindsay said.

Still, patients taking prebiotics had more flatulence and borborygmus compared with those on placebo (10.8% versus 7.3%, P=0.004 and 8.3% versus 6.1%, P=0.029, respectively). Lindsay said that’s because of increased fermentation in the gut among prebiotic users.

But overall, there were no differences in changes in gut bacteria at the end of the study.

Lindsay said that could possibly be due to a short follow-up, although that’s unlikely because four weeks should be sufficient time to see any changes in bacterial colonization.

So the researchers concluded that patients with active Crohn’s disease won’t clinically benefit from a diet supplemented with prebiotics, even though it does appear to impact immunology.