The study below demonstrates a very low carbohydrate diet improved all aspects of IBS.

Background & Aims: Patients with diarrhea-predominant irritable bowel syndrome (IBS-D) anecdotally report symptom improvement after initiating a very low-carbohydrate diet (VLCD). This study prospectively evaluated a VLCD in IBS-D.

Methods: Participants with moderate to severe IBS-D were provided a 2-week standard diet, then 4 weeks of a VLCD (20 g carbohydrates/d). A responder was defined as having adequate relief of gastrointestinal symptoms for 2 or more weeks during the VLCD. Changes in abdominal pain, stool habits, and quality of life also were measured.

Results: Of the 17 participants enrolled, 13 completed the study and all met the responder definition, with 10 (77%) reporting adequate relief for all 4 VLCD weeks. Stool frequency decreased (2.6 ± 0.8/d to 1.4 ± 0.6/d; P < .001). Stool consistency improved from diarrheal to normal form (Bristol Stool Score, 5.3 ± 0.7 to 3.8 ± 1.2; P < .001). Pain scores and quality-of-life measures significantly improved. Outcomes were independent of weight loss.

Conclusions: A VLCD provides adequate relief, and improves abdominal pain, stool habits, and quality of life in IBS-D.
Source: http://www.cghjournal.org/article/S1542-3565%2809%2900198-0/abstract

In my previous post I discussed carbohydrate malabsorption and gut inflammation. If significantly reducing carb consumption improves all symptoms, does it also reduce the level of inflammation in IBS sufferers’ guts? That would be an interesting study and I have no doubt that carb reduction does reduce low-grade inflammation in the guts of sufferers, and it would also demonstrate the link between sugar consumption and gut inflammation.