Orlistat (brand name Alli) is an over-the-counter weight loss drug that decreases fat absorption by inhibiting a digestive enzyme called gastrointestinal lipase. As a result, the large bowel is exposed to increased fat as well as altered amounts of other stool chemicals such as bile acid and free fatty acids. To determine whether these alterations might cause an increased risk for cancer, researchers launched a study to look for an early marker of cancer risk in the colon: increased cell multiplication. From the Department of Cell and Molecular Pharmacology and Experimental Therapeutics at MUSC, researcher Dr. Michael Wargovich and colleagues joined forces to answer this question.
The researchers studied 24 obese subjects who consumed 120 mg of orlistat 3 times a day for 6 weeks. Participants were hospitalized during days 1-3 and 33-42 of treatment and were treated as outpatients for the remaining days. Half of subjects were randomly assigned to take orlistat and the other half took placebo, an inactive substance. Neither the subjects nor the doctors knew whether the subjects were taking orlistat or placebo until the code was broken at the end of the study. Meanwhile, doctors measured levels of fecal fats and bile acid and studied the appearance of the lining (mucosal) cells of the intestine to check for increased cell multiplication, an early sign of change that precedes the onset of cancer.
Good news for orlistat users: As expected, treatment with orlistat for 6 weeks resulted in the passing of fat in the stools and bile acid changes were also observed. But most importantly, orlistat did not alter colonic cell proliferation, a marker that may be associated with increased risk for colon cancer.
Ahnen Dennis J; Guerciolini Roberto; Hauptman Jonathan; Blotner Steven; Woods Cindy J; Wargovich Michael J
Effect of orlistat on fecal fat, fecal biliary acids, and colonic cell proliferation in obese subjects.
Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. 2007;5(11):1291-9.