A new study on Friday suggests that wheat bran and other fibrous foods that do not dissolve easily in water not only fail to soothe irritable bowels but may even make things worse, AFP reported.
The study found that most soluble types of bran, such as psyllium, appear to ease inflamed bowels, but the insoluble varieties people have traditionally eaten for regularity don't work as advertised.
The hard outer layer of grains is referred to as bran. Psyllium, also referred to as isphagula, is derived from the seed husks of the Plantago ovata plant, and is the chief ingredient in many over-the-counter laxatives.
Irritable bowel syndrome (IBS), which affects about 10 percent of the population, causes abdominal pain and an irregular bowel habit.
Doctors all over the world recommend daily doses of fiber in the form of insoluble bran, but few studies have been done to prove that boosting intake of this type of fiber is really efficient.
researchers from the Netherlands set up clinical trials to explore bran’s effectiveness by dividing 275 patients into three groups -- giving each a different 12-week treatment regimen.
One group was given 10-grams of bran twice a day, while the second ate the same quantities of psyllium, which forms a gel-like substance when mixed with water. The third group ate a neutral placebo made out of rice flour, which contains no fiber at all.
Over three-quarters of the participants were women, as women are known to suffer from IBS more than men. The patients had either been diagnosed as having the syndrome within the last two years, or fulfilled other criteria for chronic bowel-related issues.
Psyllium was found to be the most effective treatment after only one month, according to a standardized scale measuring the severity of symptoms.
Inflammations was reduced by 90 points in the psyllium group, 49 points in the placebo group, and 58 points in the bran group after three months of trial tests.
The researchers noted a statistically insignificant difference between the bran and the rice gruel placebo.
The researchers reported in the British Medical Journal that bran showed no clinically relevant benefits, and many patients seemed not to tolerate bran.
"Indeed, bran may worsen symptoms of irritable bowel syndrome and should be advised only with caution," they wrote.
Past studies suggest soluble fibers promote healthy blood cholesterol levels and a better regulation of blood sugar.
Psyllium, barley, oatmeal, lentils, fruit and vegetables all contain soluble fiber.