Dietary intake and quality in irritable bowel syndrome: a comparative study with controls and the association with symptom severity.

Background: Patients with irritable bowel syndrome (IBS) often attribute the onset or worsening of gastrointestinal symptoms to intake of food. Hence, in order to alleviate symptoms, patients with IBS may avoid triggering foods, potentially impacting their dietary intake and diet quality. This study aimed to compare the habitual diet intake and quality of IBS patients with controls, and to explore the association between dietary habits and symptoms in IBS patients.

Methods: IBS patients were included from four clinical studies reporting habitual dietary intakes at baseline. Age- and sex-matched controls representing the general population were derived from the Swedish population-based Riksmaten study. Dietary intakes were assessed using 4-day food diaries. Diet quality was measured using a diet quality index (DQI-SNR), and diet diversity was scored based on the variety of food groups consumed.

Results: The study included 646 patients with IBS and 646 controls (38±14 years, 77% female). Both groups adhered to Nordic nutrition recommendations for macronutrients, except patients consumed fewer carbohydrates. Patients reported eating less carbohydrates, coffee, and dairy products, and more fats, lactose-free dairy products, and nuts and seeds compared to controls. Fewer patients had a good diet quality according to the DQI-SNR. In patients, symptom severity and gastrointestinal-specific anxiety were associated with reduced energy and carbohydrate intake, lower diet diversity, and worse diet quality. Poor diet quality was associated with younger age, more severe IBS symptoms, anxiety, and depression.

Conclusion: Patients with IBS exhibit different dietary patterns compared to controls, with poorer dietary habits linked to more severe symptoms. Understanding food-symptom associations may enhance the optimization and personalization of dietary management for IBS patients.