Aug. 28 (HealthDay News) -- People with the chronic condition known as irritable bowel syndrome may find relief by consuming soluble fiber (psyllium).

But they'll get no relief -- and perhaps more bowel upset -- from bran, a new Dutch study found.

IBS, which involves chronic abdominal discomfort and irregular bowel habits, affects about one in 10 Americans. Some experts have advised increased intake of dietary fiber, but data on the effectiveness of this approach has been limited.

In the study, published online Aug. 28 in BMJ, a team at the University Medical Center Utrecht had 275 adult patients with IBS consume either 10 grams of psyllium (soluble fiber), bran (insoluble fiber) or a placebo twice daily for three months. They then checked patient symptoms at one, two and three months, including abdominal pain and quality of life.

The researchers found psyllium to be most effective in treating IBS. After three months of follow-up, people taking psyllium had a 90-point drop in symptom severity, on average. This compared to a 58-point drop among those taking bran and 49-point drop for those taking the placebo. While symptom severity was eased, the researchers found no difference between the groups in terms of abdominal pain or quality of life.

Bran showed "no clinically relevant benefit," the researchers said in a news release. In fact, many patients couldn't tolerate the bran and this group experienced the highest dropout rate.

The findings suggest that psyllium, but not bran, may be a useful first treatment approach to help manage IBS, the researchers said, while bran may not help -- or may even exacerbate -- the condition.

SOURCE: BMJ, news release, Aug. 28, 2009