For people with irritable bowel syndrome (IBS), a diet that limits carbohydrates—and certain ones in particular—may bring more relief than medication, according to a new well-conducted study.
IBS is an often debilitating condition that causes chronic abdominal pain, along with constipation or diarrhea—or sometimes both. It can be difficult to manage, and doctors often recommend some combination of diet changes and other lifestyle measures (like getting more exercise), medication, and probiotics or other supplements such as peppermint oil.
There has been relatively little research comparing the effectiveness of dietary tactics versus medication, however. The new study, published in The Lancet Gastroenterology & Hepatology, is among the first. It focused on a diet commonly recommended for IBS known as low-FODMAP, which restricts particular carbohydrates that are poorly digested and thus tend to trigger IBS symptoms in susceptible people. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols—the short-chain carbohydrates (sugars) that are the culprits.
The particular carbohydrates restricted include wheat-based products, most conventional dairy foods, many fruits and vegetables, most legumes, and various sweeteners. Low-FODMAP does not equal low-carb, however: People are free to eat foods like rice, potatoes, quinoa, lactose-free dairy products, and certain fruits and vegetables like carrots, oranges, and raspberries.
The study, from Sweden, involved nearly 300 adults, mostly women, with moderate to severe IBS who were randomly assigned to one of three groups. In one, participants followed a low-FODMAP diet and received standard dietary advice for dealing with IBS, such as eating slowly and limiting coffee and alcohol. A second group followed a low-carbohydrate diet (10 percent of daily calories from carbs) that included foods like seeds and special low-carb bread to optimize fiber intake. The third group received medication based on their primary symptoms; if constipation was the main complaint, for example, a laxative was given.
After four weeks, those in all three groups were faring better—but the diet groups showed greater improvement: 76 percent and 71 percent of the low-FODMAP and low-carb groups, respectively, reported a significant reduction in IBS symptoms, versus 58 percent of participants using medication. It’s not clear why the low-carb diet worked about as well as low-FODMAP, but the researchers noted that the carb restriction, by default, reduced intake of many of the same foods targeted by a low-FODMAP diet. Of note, all three groups also reported improvement in quality of life and psychological symptoms like depression and anxiety that may accompany IBS.
The study did not obtain data beyond four weeks to know whether there would be more separation in outcomes of the three treatment options. Still, the findings suggest that dietary tactics can be a good way to manage IBS. In fact, the researchers concluded that diet changes might be considered as first-line treatments. One important point, though, is that the initial low-FODMAP restrictions are not meant to be forever: Once symptoms improve, restricted foods can be gradually reintroduced to see which ones are tolerable. The goal is to have both IBS relief and the most diverse, nutritious diet possible. It’s also worth noting that many study participants on medication got symptom relief. For some people, a combination of diet changes and medication might be optimal.
BOTTOM LINE: Based on the study findings, if you have IBS, you might want to try a low-carb diet before attempting a more-challenging low-FODMAP diet. Either way, a registered dietitian/nutritionist (RDN) can help craft a personalized eating plan that’s effective and nutritionally balanced. There are also many online FODMAP resources, notably from Monash University in Australia, where the diet was developed. The website provides a list of FODMAP-tested foods, recipes, an app you can download on your phone, and a directory of FODMAP-trained dietitians who have passed Monash University’s online course, though the university does not specifically endorse them (you must do your own due diligence).
