How does reducing colonic transit time with fiber prevent colorectal cancer?

Less contact. The hypothesis is that one factor in colon cancer is potentially ingested carcinogens(cancer causing) that are in the food we eat. The faster the stool moves through the colon, the less time the carcinogen has in contact with any segment of the colon so it's should be less damaging.
Inflammation! Although the data supports a healthy diet high in fiber with fruits and vegetables improves colonic health - there is some speculation that it may also reduce the risk of colorectal cancer. A diet high in dietary fiber reduces colonic transit time - meaning you go more regularly. The more regular you move your bowels there is less stagnation of stool and decreased inflammation in the colon.
It doesnt. That was antheory espoused several years ago based on population based studies but it never panned out.

Related Questions

What can you tell me regarding rare types of colon (colorectal) cancer?

Sure. The most common kind of colon cancer is adenocarcinoma. There are however many more rate types of colon cancer. You can find out more about these at cancer.Gov or on the pub med website. Read more...

Why is the colon prone to cancer in hnpcc (hereditary nonpolyposis colorectal cancer)?

Genetic mutations. HNPCC or hereditary nonpolyposis colorectal cancer is an autosomal dominant genetic condition that has a high risk of colon cancer The disease first described by Lynch and is associated with other cancers including endometrial ovary and stomach. The increased risk is due to inherited mutations that impair DNA mismatch repair. .Individuals with HNPCC have an 80% lifetime risk for colon ca. Read more...

Colon cancer or colorectal cancer, what's the difference?

Location. Cancers that arise from the epithelium of the large intestine are similar in most ways whether they are in the colon or rectum. Discussions of "colon cancer" unspecified usually mean "colorectal" unless stated otherwise. Usage, including by me, is often sloppy. Read more...

Are colorectal cancer and colon cancer the same thing with different locations?

Can be. Colon cancer and colon-rectal cancer are usually an adenocarcinoma, requiring surgery and sometimes chemotherapy. Colon cancer would occur somewhere in the large intestine, and rectal cancer in the lower anatomic location. Rectal cancers may be treated with chemotherapy and radiation therapy before surgery due to its location and research sowing the benefits of treatments before surgery. Read more...
Yes and no. Both are adenocarcinomas of the 'large intestine' broadly speaking. However, due to several anatomic differences, colon and rectal cancer behave differently. For that reason the preoperative staging is different and the treatment can be different (surgery +/-chemotherapy for colon cancer, surgery +/- chemoradiation therapy for rectal cancer). The functional outcomes are different as well. Read more...

For what reason colon part is usually prone to cancer in hnpcc (hereditary hereditary nonpolyposis colorectal cancer)?

Genetic disorder. Hnpcc also called lynch syndrome results from at least four type of genetic defects involving genes needed for repair of damaged dna. See this site for more info. http://ghr.nlm.nih.gov/condition/lynch-syndrome. Read more...

Having surgery for colorectal cancer? How much of the colon does the doctor take out? Will I have normal bowel function after?

You . You have to know what part of teh colon its going to take out. Its the rigth side will be almost normal may have alittle od los bowel in the firts 3 months. Its the left will be loss for 6 months but only in consistence. Its the rectum may change you ability of sensation, consistency and frequency. Read more...
Depends on location. Stage, size and location of the tumor determine how much colon and therefore how much impact on your bowel function you will experience. Read more...
Depends on location. Colon cancer is usually treated with wide removal of the segment of colon involved along with the lymph nodes draining that segment. The ends of the remaining intestine are reattached with staples or sutures. Bowel function is usually altered minimally unless there is more than one cancer and the entire colon is removed and sewn to the rectum. In that case, you might have frequent bms. Read more...