Soluble Versus Insoluble Fiber in IBS

For those with irritable bowel syndrome (IBS), controlling your diet is a very important part of reducing the symptoms of the condition. In many cases, dietary fiber has been shown to lessen the symptoms of IBS. A high fiber diet will ensure that the waste that passes through your colon is "bulky", which may prevent diarrhea and relieve muscle spasms.

There are two types of dietary fiber: soluble and insoluble. In previous years, it was thought that either type of dietary fiber would provide a benefit to suffers, but a greater benefit to those with diarrhea-predominant symptoms. An increasing body of scientific literature now indicates that the benefits of soluble fiber are universal to sufferers whose symptoms are either diarrhea-predominant or constipation-predominant, and that insoluble fiber can actually trigger or exacerbate symptoms in some patients.

Soluble substances are those can be dissolved in water, whereas insoluble substances cannot. Soluble substances also tend to absorb water, which is where the principal benefit for IBS sufferers is derived. In comparison to insoluble fiber, the sugar molecules of soluble fiber are held together by chemical bonds that cannot be digested by the enzymes in the human gastrointestinal (GI) tract. As such, soluble fiber passes straight through your body intact meaning that more soluble fiber arrives in the colon and is available to absorb water. Water absorption from the colon by the fecal matter encourages the formation of stools that are gel-like, which helps to prevent diarrhea.

But additional water absorption doesn't mean that constipation-predominant sufferers will be adversely affected. In fact, the absorptive properties of soluble fiber mean that the passage of softer, gel-like waste will actually soften and encourage excretion of impacted fecal matter.

Further, the gel-like consistency of waste containing soluble fiber means that the GI muscles are stretched around your full colon, which helps the muscles to grip during the waves of peristaltic contractions that act to force the waste through your gut. Violent and irregular muscle spasms are minimized, which means that abdominal cramping is also relieved.

So where do you find the different forms of fiber? Both insoluble and soluble fiber are contained in all plants foods, with the ratio varying dependent on the plant type. Insoluble fiber is typically found in whole wheat, wheat and corn bran, flax seed lignans and vegetables including carrots, celery, green beans and potato skin. Soluble fiber is found in rice and rice cereals, pasta, oatmeal, cornmeal, barley, quinoa and soy. You can also find soluble fiber in vegetables such as carrots, yams, sweet potatoes, turnips, pumpkins and mushrooms. Papayas are also a particularly good source of soluble fiber, with the added bonus that they are a digestive aid that relieves flatulence and indigestion.

Adopting a diet high in soluble fiber can help you manage the symptoms of irritable bowel syndrome. It can be beneficial to speak to a dietitian or medical practitioner about your new diet, to ensure that it is balanced and nutritious.