A study looking at the effect of non digestible carbohydrates on bowel cells (DISC study)

Cancer type:

Bowel (colorectal) cancer





This study was done to see how non digestible carbohydrates affect healthy bowel cells and whether they can help prevent bowel cancer.

More about this trial

Non digestible carbohydrates (NDCs) include resistant starch and polydextrose. The body cannot digest or absorb these forms of carbohydrate. But healthy bacteria in the bowel can break them down (ferment them) into other substances. These include acetate, butyrate and propionate.

Research has shown that these substances can help prevent bowel cancer in a number of different ways. 

Butyrate has been shown to help regulate growth of bowel cells, and reduce inflammation. It may also help regulate a series of reactions in the cells called the Wnt pathway. The Wnt pathway is often over active in bowel cancer cells. 

The research team took tissue samples (biopsies) from the lining of the bowel. They looked at the genetic material (DNA) in the cells, to see if there were any changes.

They also took samples of poo (stool) and measured the amount of a protein called calprotectin. The level of calprotectin is usually higher if the lining of the bowel is inflamed or damaged.

Researchers doing this study wanted to find out whether NDCs could affect the Wnt pathway and help prevent bowel cancer.

Summary of results

The research team found that resistant starch and polydextrose didn’t affect calprotectin levels, but did affect some genes linked to bowel cancer.
This trial was open for people to join between 2010 and 2011, and the research team first published results in 2016. 
About this study
The people taking part in this study were put into 1 of 4 groups at random:
  • Group 1 had had dummy (placebo) powder 
  • Group 2 had resistant starch powder
  • Group 3 had polydextrose powder
  • Group 4 resistant starch and polydextrose powder
Everyone taking part had had seen a doctor and had an colonoscopy to investigate bowel symptoms. But they didn’t have bowel cancer.
They all had the carbohydrate (or placebo) powder every day, for 50 days. They could add it to cold food or drinks. 
Neither the people taking part nor the research team could chose, or knew, which group they were in. This is called a double blind study.
The 88 people who took part were put into 1 of the 4 treatment groups at random, and:
  • 22 had the placebo
  • 22 had resistant starch
  • 23 had polydextrose
  • 21 had resistant starch and polydextrose

Calprotectin results
The research team looked at the level of calprotectin in the stool samples, and found there was little difference between the groups. Neither resistant starch or polydextrose (or a combination of the two) affected calprotectin levels. 

These results suggest that measuring calprotectin in stool samples is not an accurate way to assess inflammation and bowel cancer risk. Or it may be that the carbohydrates used in this study didn’t change calprotectin levels.
Wnt pathway results 
The team also looked at 12 genes of the Wnt pathway. Genes are coded messages that tell cells which proteins to make. They can be turned on and off. When a gene is turned on (activated) to make a protein, it is called gene expression. 
The team found that resistant starch and polydextrose both reduced the expression of a gene called SFRP1. And polydextrose reduced the expression of another gene called SFRP2, but resistant starch did not.
These results were a bit unexpected. Increased expression of these genes usually reduces signals in the Wnt pathway. So decreased expression of these genes may mean that the Wnt pathway is more active. And this would suggest an increased (rather than decreased) risk of bowel cancer.
The research team suggest that not all non digestible carbohydrates (NDCs) affect bowel cancer risk. And those that do, may work on other pathways or affect different cells within the bowel.
Micro genetic analysis
Within our cells there are tiny bits of genetic material called micro RNA, or miRNA. They help control how much of each protein is made, and this effects how different cells divide and grow. If the miRNA are disrupted, this can affect the risk of developing cancer.
The research team looked at more than 1,000 different miRNAs from the people taking part in this study. They found that people who had non digestible carbohydrates had different amounts of 111 miRNAs:
  • more than usual of 33 
  • less than usual of 78
There was much more than usual of one miRNA called miR-32. Other research had already shown that miR-32 helps regulate some processes in cells. These processes are often disrupted in cancer cells. So having more miR-32 may help stop the disruption, and so reduce the risk of bowel cancer.
The research team concluded that resistant starch and polydextrose do not affect the amount of calprotectin in stool samples. But these carbohydrates can affect the expression of some genes in healthy bowel cells. 
They suggest more work is done to find out more about the Wnt pathway and miRNA in bowel cells. 
Where this information comes from
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor John Mathers

Supported by

Biotechnology and Biological Sciences Research Council
NIHR Clinical Research Network: Cancer
Northumbria Healthcare NHS Foundation Trust
University of Newcastle


If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Alan took part in a clinical trial for bowel cancer patients

A picture of ALan

“I think it’s essential that people keep signing up to these type of trials to push research forward.”

Last reviewed:

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