Smokers are at a significantly higher risk for colon polyps than nonsmokers and risk increases with duration of smoking, according to a presentation at the annual meeting of the American College of Gastroenterology.

The American investigators had examined the relationship between polyps and dietary and recreational habits as well as medications in a prospective study of 157 patients with a mean age of 55 years. The researchers gathered a range of demographic and health information, including smoking history and use of herbal and nutraceutical supplements including vitamins and minerals, among other information. Participants underwent colonoscopy screening to detect polyps and colorectal cancer.

The researchers found cigarette smokers were more likely to have polyps, to have a greater number of polyps, and to have larger polyps than non-smokers. A logistic regression analysis determined a four percent increased risk of polyps for every additional year of smoking.

Interestingly, the researchers found there was a significant association between use of vitamin C and absence of polyps (p=0.023). In this sample, none of the 16 patients who regularly consumed vitamin C supplements at doses equal to or more than 1000 mg daily had polyps.

In the other arm of the study, the researchers conducted a retrospective review of patients who underwent colonoscopy, excluding patients with a history of colon cancer or colon surgery. Their study included 177 patients with a median age of 65 years. Of the group, 57 percent had polyps located on the left side of the colon.

When analyzed for all ages, left-sided polyps showed a statistically significant association with a history of smoking. Among all ages of smokers, the chance of left-sided polyps was 2.7 times higher than among non-smokers. This association was even more significant in smokers above 50 years of age. The probability of left-sided polyps was three times greater among smokers over 50 than non-smokers over 50 years.

The researchers stressed that future studies with better quantification of smoking history would be required to evaluate this association.