Editorial: Food for Thought—Addressing the Nuances of Diet and Mood When Evaluating Dietary Intervention in IBS

Abstract

In the study by O'Connor et al. participants with primarily IBS-D undergoing a group-based education program on the British Dietary Association's advice for IBS were less likely to achieve the 12-week primary endpoint (50-point reduction in the IBS Symptom Severity Scale) if they had elevated levels of depression or anxiety at baseline [1].

We appreciate the complex undertaking of evaluating psychological factors as part of dietary intervention, in pursuit of the growing need for personalised, integrated care for IBS [2]. Unfortunately, a few missed opportunities in the study design make it hard to reconcile the complex intersection between psychological “influencers” such as depression and anxiety, eating behaviours, IBS symptoms and response to dietary treatment.

First, reliance on the Hospital Anxiety and Depression Scale (HADS) > 8 as an indicator of psychiatric distress fails to consider the psychological nuances seen in patients with IBS, particularly with respect to their personal responses to gastrointestinal symptoms. Although generalised anxiety and major depression are associated with IBS [3], there seems to be a stronger relationship with symptom-specific anxiety, a well-established driver of IBS and a known risk factor for disordered/restricted eating behaviour [4]. Further, only baseline measures of depression and anxiety were considered, inhibiting the ability to determine the bi-directional and ongoing associations between depression, diet and IBS in response to intervention. Since there was no evaluation of whether anxiety and depression symptoms varied with IBS symptom severity after the intervention, it cannot be assumed that HADS scores were independent predictors of dietary response. Finally, the co-association of IBS symptom severity and symptoms of anxiety and depression at baseline begs the question of whether reductions in IBS symptoms were related to the reduction in symptoms of anxiety and depression due to following a healthy diet, which is quite plausible given the host of studies establishing the impact of diet interventions (e.g., Mediterranean diet) independently on psychological symptoms and well-being [3].

Finally, while the discussion section suggests that patients with greater severity of IBS symptoms may affect dietary behaviour (e.g., patients with more bothersome symptoms being more motivated to adhere to dietary guidance), there was no consideration of how symptoms of depression or anxiety (including fear of eating differently) may have the opposite effect on diet behaviour. Without data on dietary adherence over the 12-week intervention period, the team missed an opportunity to explore what, if any, relationships exist between motivation, symptom severity and depressive or anxiety symptoms.

There is certainly a need for more studies at the intersection of food and mood, particularly those that include measures of psychological distress, including symptom specific anxiety, measured at more frequent intervals. Future studies that consider the impact of mood and anxiety on dietary intervention motivation, adherence and adverse effects (e.g., eating disorder behaviour) would shed more light on these results, help to uncover the underlying mechanisms at play, and ideally lead to more personalised and more efficacious treatments.

Cecilia Katzenstein: writing – original draft, conceptualization, investigation. Laurie Keefer: writing – review and editing, supervision.

Cecilia Katzenstein: None. Laurie Keefer: Consultant to Pfizer, Eli Lilly, Janssen, Reckitt, Coprata Health; unrestricted research funds Ardelyx, Leona M and Harry B Helmsley Charitable Trust, Equity owner and co-founder Trellus Health, Board of Directors, Rome Foundation.

This article is linked to O’Connor et al papers. To view these articles, visit https://doi.org/10.1111/apt.18337 and https://doi.org/10.1111/apt.18384.