March 23, 2015
Written by David Rakel MD, FAAFP
Overall, four questions can help guide nutritional therapy for irritable bowel syndrome (IBS).
Question 1: What is the diet like?
Some patients drink three pots of coffee a day or only eat pizza for breakfast, lunch, and dinner. We don’t know if we don’t ask, and when we hear stories like this, we have some low-hanging fruit to start treatment on improving their overall nutrition.
Question 2: Are there specific chemicals in food that trigger symptoms?
Some of the most common triggers of IBS symptoms are monosodium glutamate (MSG), which gives food a salty flavor and is often an ingredient in soups and croutons. Tartrazine, or yellow #5, has been banned in numerous countries (but not in the United States) due to its allergenic potential. Sodium benzoate is a food preservative found in condiments and soda. Polyol sweeteners, such as sorbitol, can trigger bowel spasms. I have had a couple lucky patients whose IBS resolved when they stopped chewing sugarless gum. Avoiding polyol sugars is also part of the FODMaP diet. They are the “P” at the end.
Question 3: Is there more diarrhea or constipation?
If there is more diarrhea, patients often respond best to the FODMaP diet. It is low in sugars, which are difficult to absorb, leading to fermentation and gas, while also being osmotic, pulling fluid into the intestine and worsening the diarrhea. Although the diet has been found to be helpful in people with both diarrhea- and constipation-dominant IBS, it has has a greater therapeutic effect in those with frequent bowel movements.1 A summary of this diet can be found here. The authors of a recently published review in Gastroenterology2 have also created a Low FODMaP Diet app, which may prove beneficial to your patients.
My concern with long-term use of the FODMaP diet is that it removes a lot of healthy foods and it can be quite restrictive. If the patient with IBS responds, he or she will often do so within a week. Some clinicians have responders slowly add back in foods as they are able, allowing them to fine-tune a diet that is less restrictive long-term.2
Question 4: Are there foods the patient craves or eats a lot of?
Some food proteins, such as gluten and casein, can stimulate enteral opioids called exorphins, causing individuals to occasionally crave the very food that may be causing the problem. When taking a nutritional history, if a patient with IBS indicates that he or she craves a big bowl of ice cream each night, have the patient avoid it for 2 weeks and see if symptoms improve. Food intolerances have been found to stimulate lymphocytic infiltrations along the gut lining. Gluten (in wheat) and casein/whey (in dairy) are the most common, but soy, shellfish, peanuts, yeast, and eggs contain others. For guidance on how to do an elimination diet, click here.
The most important thing to avoid is the risk of creating a fear of food. The research in this area shows a high nocebo effect, meaning that a fear of food may cause symptoms even if there is no immune intolerance. It is our job to help patients find a balance wherein they can have a harmonious relationship with one of life’s pleasures without having to run to the bathroom.