What is modified citrus pectin?

Modified citrus pectin (MCP) is an alternative therapy that is claimed to stop prostate cancer and melanoma from spreading. Pectin is found in many fruits, including citrus fruits. It is what we use to make jam set, and is found mostly in the pips and the pith of citrus fruits. The pectin in modified citrus pectin has been changed to make it easier for the body to take in through the gut. You take it as a capsule or a powder.

Alternative therapists claim that pectin may help with prostate cancer and melanoma because these cancers have been tested in animal studies using MCP. In mice, MCP seemed to lower the risk of prostate cancer spread to the lungs. Also in mice, it seemed to result in less melanoma spread to the lungs. So MCP may make it harder for cancer cells to break away and spread in mice. But it hasn't yet been shown to affect primary cancers (the original tumour). It has also not been shown to have any activity in fighting cancer in people.

One study in humans has tested modified citrus pectin (MCP). This was a small pilot study looking at the effect of MCP on prostate specific antigen (PSA). Prostate Specific Antigen is a protein produced by prostate cells. It is produced in higher amounts by prostate cancer cells. The study looked at the time it took for PSA to double in men with prostate cancer who had not responded to treatment at all, or whose cancer had begun to grow again after treatment.

It did seem to take longer for the PSA to double in some of the men on the trial. But the researchers decided that more trials with larger numbers of patients will have to be done before we know if MCP is of any use in prostate cancer treatment. Until such studies are carried out and published, Cancer Research UK will not be able to offer any other view on this substance.

The American Cancer Society has a page about citrus pectin on their website.