Clin Gastroenterol Hepatol. 2021 May 19;S1542-3565(21)00565-6.doi: 10.1016/j.cgh.2021.05.027. Online ahead of print.

Adrienne Lenhart ¹, Tien Dong ¹, Swapna Joshi ², Nancee Jaffe ¹, Charlene Choo ³, Cathy Liu ², Jonathan P Jacobs ⁴, Venu Lagishetty ¹, Wendy Shih ⁵, Jennifer S Labus ², Arpana Gupta ², Kirsten Tillisch ², Emeran A Mayer ², Lin Chang ⁶

Author information

• ¹Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California, Los Angeles, United States.
• ²G Oppenheimer Center for Neurobiology of Stress and Resilience; Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California, Los Angeles, United States.
• ³David Geffen School of Medicine, University of California, Los Angeles, United States.
• ⁴Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California, Los Angeles, United States,; Division of Gastroenterology, Hepatology and Parenteral Nutrition, Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, United States.
• ⁵Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, United States.
• ⁶G Oppenheimer Center for Neurobiology of Stress and Resilience; Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, University of California, Los Angeles, United States,. Electronic address: LinChang@mednet.ucla.edu.

Abstract

Background & aims: Altered fecal microbiota have been reported in IBS, although studies vary which could be due to dietary effects. Many IBS patients may eliminate certain foods because of their symptoms, which in turn may alter fecal microbiota diversity and composition. This study aims were to determine if dietary patterns were associated with IBS, symptoms, and fecal microbiota differences reported in IBS.

Methods: 346 IBS participants and 170 healthy controls (HCs) completed a Diet Checklist reflecting the diet(s) consumed most frequently. An exclusion diet was defined as a diet that eliminated food components by choice. Within this group, a gluten-free, dairy-free, or low FODMAP diet was further defined as restrictive as they are often implicated to reduce symptoms. Stool samples were obtained from 171 IBS patients and 98 HCs for 16S rRNA gene sequencing and microbial composition analysis.

Results: Having IBS symptoms was associated with consuming a restrictive diet (27.17% of IBS patients vs 7.65% of HCs; OR 3.25; 95% CI 1.66-6.75; p-value 0.006). IBS participants on an exclusion or restrictive diet reported more severe IBS symptoms (p=0.042 and p=0.029 respectively). The composition of the microbiota in IBS patients varied depending on the diet consumed. IBS participants on an exclusion diet had a greater abundance of Lachnospira and a lower abundance of Eubacterium (q-values<0.05) and those on a restrictive diet had a lower abundance of Lactobacillus (q-value <0.05).

Conclusions: Restrictive diets are likely consumed more by IBS patients than HCs to reduce GI symptom severity. Dietary patterns influence the composition of fecal microbiota and may explain some of the differences between IBS and HCs.