Personalized Research on Diet in Ulcerative Colitis and Crohn's Disease: A Series of N-of-1 Diet Trials

Review article: Evidence-based dietary management of inflammatory bowel disease

BACKGROUND

Dietary management of patients with inflammatory bowel disease (IBD) involves more than defining a therapeutic diet. The profusion of 'expert advice' is not necessarily built on evidence.

AIMS

To provide evidence-based guidance on all clinically relevant aspects of nutritional and dietary management of patients with IBD.

METHODS

A comprehensive review of the published literature was made.

RESULTS

Four pillars of management should be considered in all patients. First, nutritional status should be optimised, since myopenia and visceral obesity are associated with poorer outcomes, which can be improved with attention to their correction. Accurate point-of-care measurement of body composition is advocated to identify problems, guide interventions and monitor outcomes. Second, exclusive enteral nutrition and the Crohn's Disease Exclusion Diet with partial enteral nutrition in reducing intestinal inflammation in patients with Crohn's disease have sufficient evidence to be advocated. Multiple other dietary approaches, while promising, have insufficient evidence to be recommended. Third, dietary approaches are important in symptomatic control in many non-inflammatory scenarios. Finally, guidance on following a healthy diet is fundamental to the general health of patients. Multiple approaches are advocated, but the optimal strategy is unclear. The precarious nutritional status of patients with IBD together with the risks of nutritional inadequacy and maladaptive eating behaviours associated with restrictive diets dictate involvement of expert dietitians in assessment and personalised delivery of dietary interventions.

CONCLUSIONS

Four pillars of nutritional management require specific assessment and interventional strategies that should be chosen by evidence. Optimal delivery requires the skills of a specialised dietitian.

Personalized (N-of-1) Clinical Trials for Inflammatory Bowel Disease: Opportunities and Challenges

BACKGROUND & AIMS

Heterogeneity of treatment effects in inflammatory bowel disease (IBD) means that many individuals or patient subgroups depart from the average for whom the outcomes from traditional randomized trials may not be applicable. The N-of-1 trial is a design in which a single patient is followed over time with the treatments being randomized from period to period with the intention of finding the most effective treatment for that patient. The aim was to investigate the utility of N-of-1 trials in IBD.

METHODS

To identify relevant articles for this scoping review, a MEDLINE literature search was conducted through the PubMed platform for articles published in the English language using the search terms "inflammatory bowel disease," "Crohn's disease," "ulcerative colitis," "N-of-1 trials," "single case designs," and "personalized trials."

RESULTS

N-of-1 trials have seen a resurgence across several medical disciplines, driven by a need for more personalized medicine and patient-centered health care; their use in IBD is scarce with only 3 trials identified. Studies involving multiple N-of-1 trials can generate robust evidence for each participant and average effect estimates. The N-of-1 trial may hold potential for studying patients with IBD that are excluded from or underrepresented by randomized trials, such as those with extraintestinal manifestations, pouchitis, and proctitis. Although methodologically sound and akin to the rigor of a randomized controlled trial, the crossover periods inherent to the study design can be perceived as burdensome by patients and researchers.

CONCLUSIONS

The N-of-1 trial design provides a patient-centered means of objectively determining individual response to therapy.

N-of-1 trials in epilepsy: A systematic review and lessons paving the way forward

OBJECTIVE

Defined as prospective single-patient crossover studies with repeated paired cycles of active and control intervention, N-of-1 trials have gained attention as an option to obtain high-quality evidence of efficacy, particularly for patients with rare epilepsies in whom conduction of well-powered randomized controlled trials can be challenging. The objective of this systematic review is to provide an appraisal of the literature on N-of-1 trials in individuals with epilepsy.

METHODS

We searched PubMed and Embase on January 12, 2024, for studies meeting the following criteria: prospectively planned, within-patient, multiple-crossover design in individuals with epilepsy and outcomes related to comorbidities. Information on design, outcome measurements, intervention, and analyses was retrieved. Risk of bias assessment was performed using the Risk of Bias in N-of-1 Trials (RoBiNT) scale. We highlighted methodological aspects of the N-of-1 trials identified and discuss future recommendations.

RESULTS

Five studies met our inclusion criteria. An additional multiple-crossover trial that evaluated treatment effects exclusively at group level was also included because of its relevance to N-of-1 study methodology. The studies enrolled individuals with focal seizures, absences or cognitive impairement and electrographic discharges. Treatments included established or investigational antiseizure medications, off-label medications, neurostimulation or lifestyle intervention. Three of the five N-of-1 trials reported on individual cases. The studies' strengths were the use of individualized treatment dosages and symptom-specific patient-reported outcomes. Limitations were related to minimal reporting of baseline characteristics and seizure burden.

SIGNIFICANCE

The trials identified by our search exemplify how the N-of-1 design can be applied to assess interventions in individuals with epilepsy-related disorders. Future N-of-1 trials of antiseizure interventions should take into account baseline seizure frequency, should apply statistical models suited to capture seizure frequency changes reliably and make predefined interim assessments. Non-seizure outcome measures evaluable over short periods should be considered. Tailored N-of-1 methodology could pave the way to evidence-based, treatment selection for patients with rare epilepsies.

Food-Based Interventions as Therapy for Inflammatory Bowel Disease: Important Steps in Diet Trial Design and Reporting of Outcomes

Diet therapy for inflammatory bowel disease (IBD) is an international research priority but guidance for IBD-specific diet trial design is lacking. This review critically evaluates key elements of prospective IBD food-based intervention trials and identifies gaps. Electronic databases were searched for interventional IBD diet studies. Prospective primary studies/trials were included if used food-based dietary strategies. Forty studies/trials evaluating 29 food-based strategies as therapy for IBD were identified. Considerable heterogeneity in diets, trial design, and methodology exists. Thirty-one trials (78%) intended the diet to modulate inflammation but 14/31 (46%) did not have a primary endpoint measuring an objective change in inflammatory activity and 20/31 (65%) controlled for medication stability prior to application of diet at baseline. Higher-quality IBD diet trials used symptom-based assessment tools coupled with an objective evaluation of inflammatory activity. Dietary advice trials are the most common. One-third of trials developed and administered diet education without a dietitian. Evaluation and reporting on adherence to diet therapy occurred in <60% of trials. Failure to include or report on key elements of trial design reduced the interpretability and validity of the results. This is a considerable limitation to advancing scientific knowledge in this area. Diet therapy trials should adhere to similar rigorous quality standards used to develop other IBD therapies. Therefore, a set of practical recommendations was generated to provide the authors' perspective to help inform the future design of high-quality IBD diet trials.

A methodological review of randomised n-of-1 trials

BACKGROUND

n-of-1 trials are a type of crossover trial designed to optimise the evaluation of health technologies in individual patients. This trial design may be considered for the evaluation of health technologies in rare conditions where fewer patients are available to take part in research. This review describes the characteristics of randomised n-of-1 trials conducted over the span of 12 years, including how the n-of-1 design has been employed to study both rare and non-rare conditions.

METHODS

Databases and clinical trials registries were searched for articles including "n-of-1" in the title between 2011 and 2023. The reference lists of reviews identified by the searches were searched for any additional eligible articles. Randomised n-of-1 trials were selected for inclusion and data were extracted on a range of design, population, and analysis characteristics. Descriptive statistics were produced for all variables.

RESULTS

We identified 74 studies meeting our eligibility criteria, 13 of which (17.6%) were conducted in rare conditions. They were conducted in a range of clinical areas with the most common being neurological conditions (n = 16, 21.6%). The median (Q1, Q3) number of participants randomised was 9 (4, 20) and 12 trials (16.2%) involved a single patient only. Forty-six (62.2%) trials evaluated pharmaceutical interventions and 49 (66.2%) trials were placebo controlled. Trials had a median (Q1, Q3) of six (4, 8) periods and 61 (82.4%) compared two health technologies. Fifty-seven (77.0%) trials incorporated blinding and 32 (43.2%) had a washout period. Forty-nine trials (66.2%) used patient-reported outcome measures (PROMs) to assess the primary outcome. Trials used a range of approaches to analysis and 48 (64.9%) combined data from multiple patients. The characteristics of the n-of-1 trials conducted in rare conditions were generally consistent with those in non-rare conditions.

CONCLUSIONS

n-of-1 trials are still underused and the application of the n-of-1 design for the evaluation of health technologies for rare diseases has been particularly limited. We have summarised the characteristics of randomised n-of-1 trials in rare and non-rare conditions. We hope that it can inform researchers in the design of future n-of-1 studies. Further work is required to provide guidance on specific design considerations, implementation, and statistical analysis of these studies.

TRIAL REGISTRATION

Not applicable.

Diet and Nutrition in Inflammatory Bowel Disease: A Review of the Literature

Diet is thought to contribute to the development of inflammatory bowel disease (IBD) and may act as a mediator of inflammation in patients with IBD. Patients commonly associate their diet with symptoms and inquire about dietary modifications to manage their IBD. Without clinical guidelines and well-established nutritional data, healthcare providers managing patients with IBD may find it difficult to provide recommendations. Strong evidence for enteral nutrition, particularly in the pediatric population, has been established in Crohn's disease (CD) as a therapeutic option. Enteral nutrition may also serve as an adjunct to an exclusion diet. Recent studies such as the randomized trial comparing the Specific Carbohydrate Diet to a Mediterranean Diet in CD patients provide additional insights in forming dietary plans. A low-fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet in quiescent IBD and an anti-inflammatory diet have also been explored as adjunctive therapies. In this review, we discuss the latest evidence for the role of diet in IBD both as a therapeutic modality and as an opportunity to provide patient-centered care.

The Role of Diet in Pediatric Inflammatory Bowel Disease

The pathogenesis of inflammatory bowel disease (IBD) involves a complex interaction between genetics, immune response, and the environment. Epidemiologic associations between diet and development of IBD plus the ability of diet to modify the microbiota and modulate immune function have led to the hypothesis that diet can prevent and/or treat IBD. It is well established that the induction of remission and healing of the mucosa in Crohn's disease can be accomplished with exclusive enteral nutrition. Whole food-based alternatives such as the Crohn's disease exclusion diet have shown promising results.

Food for Thought: Remission of Perianal Pediatric Crohn's Disease on Specific Carbohydrate Diet Monotherapy

There is growing interest among patients about the specific carbohydrate diet (SCD) as a treatment for Crohn's disease. In the meantime, deep remission in patients using SCD as their sole treatment has not been documented. We report a case with perianal and ileocolonic Crohn's disease in whom SCD monotherapy successfully induced and maintained not only clinical, but also endoscopic, radiographic and histologic (ie, deep mucosal remission) remission as well.

A Systematic Review of the Role of Diet in Ulcerative Colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by inflammation and ulceration of the colon and rectum. Diet is an important part of UC management because it can either aggravate or alleviate symptoms along with medication therapy. A comprehensive literature search was conducted using multiple databases (PubMed and Online Wiley Library) and search engines (Google Scholar) using specific keywords related to UC and diet. The search resulted in a large number of articles, which were then narrowed down by focusing on clinical trials and randomized controlled trials published between 2010 and 2023. According to the research, certain dietary interventions, such as the low FODMAP diet, the Mediterranean diet, and the anti-inflammatory diet, appear to improve symptoms and overall quality of life. Dietary interventions have the potential to help with UC management. The goal should be to provide patients with tailored dietary interventions and other treatments to improve their quality of life. More research is needed to identify the most effective dietary interventions and better understand how they work.

Working to Answer the Effectiveness of Nutrition in IBD: Still a Ways to Go

ABSTRACT

The Specific Carbohydrate diet (SCD) is an exclusion diet widely popular among patients with IBD, which restricts carbohydrates and processed foods. Two recently concluded controlled studies PRODUCE (Personalized Research on Diet in Ulcerative Colitis (UC) and Crohn's Disease) and DINE-CD (The Diet to Induce Remission in Crohn's disease) confirm efficacy of SCD on symptom control but fail to demonstrate a sustained anti-inflammatory response. These dietary studies are a welcome addition to a poorly understood field of dietary management of IBD, we explore some practical challenges including trial designs, recruitment, and retention in long term dietary intervention studies. Future dietary intervention studies should, therefore, incorporate endoscopic end points to establish a true anti-inflammatory response to elimination diets, preferably with detailed multi-omics analysis to understand mechanism of action.

Current Nutritional Therapies in Inflammatory Bowel Disease: Improving Clinical Remission Rates and Sustainability of Long-Term Dietary Therapies

Inflammatory Bowel Disease (IBD) includes a spectrum of chronic immune-mediated intestinal diseases thought to be related to the complex interaction between the host immune system and the intestinal microbiome. Research supports the use of nutritional therapy in IBD; however, it is not routinely used in clinical practice. This literature review seeks to advance the understanding of diet and its effect in IBD with a focus on both Crohn's Disease (CD) and Ulcerative Colitis (UC). The contribution of diet to the development and treatment of IBD cannot be overstated. In both pediatric as well as adult IBD, nutritional interventions have been shown to improve clinical symptoms as well as inflammatory burden. The impact of dietary intervention is best exemplified through the use of Exclusive Enteral Nutrition (EEN) in CD. EEN and clinical research on exclusionary whole food diets-Crohn's Disease Exclusion Diet (CDED), Specific Carbohydrate Diet (SCD), low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet, and Mediterranean Diet-are discussed within this review. Current clinical literature supports the elimination of detrimental components and the incorporation of low processed whole foods in the diet. Additional prospective and longitudinal dietary studies on sustainable and long-term dietary options, along with a deeper understanding of the mechanism, are needed to further advance the role of nutritional interventions in IBD.

Personalized Dietary Regimens for Inflammatory Bowel Disease: Current Knowledge and Future Perspectives

Inflammatory bowel diseases (IBD) are chronic and incurable conditions of the gastro-intestinal tract with an increasing incidence and prevalence worldwide. Common symptoms are abdominal pain, diarrhea, and weight loss. Despite recent advances in medical management, many patients fail to achieve clinical remission and healing of the mucosa of the bowel. The cause is thought to involve an inappropriate reaction of the immune system, the microbiome and the environment in genetically susceptible individuals, leading to chronic bowel inflammation. Evidence is emerging that diet is a key environmental factor that might influence disease onset and course, and therefore may become a therapeutic strategy to mitigate inflammation and symptoms. Since IBD is a heterogeneous disease on a clinical and a molecular level, personalizing dietary advice could be the crucial factor to achieve long-lasting changes in dietary behaviors that could not only improve nutritional status but also tackle gut inflammation and abdominal symptoms on an individual level. In this review, we first discuss different aspects of personalized nutrition, namely the level, focus, and scope of personalized dietary regimens. Then, we provide a framework for the different goals of nutritional therapy in IBD and current evidence for personalized dietary approaches. Lastly, we discuss the need for adequate trial designs, access to the right data types and the bioinformatic tools that are necessary to develop algorithms that will allow us to move from general "healthy eating" advice to truly personalized nutritional plans for the individual IBD patient.

Comparison and recommendation of dietary patterns based on nutrients for Eastern and Western patients with inflammatory bowel disease

Inflammatory bowel disease (IBD), a non-specific chronic idiopathic inflammatory condition of the digestive system, requires lifelong treatment in which drugs are the mainstay, along with surgery when necessary. In adjuvant therapies, the diet is considered to be an essential, controllable, and economical component. However, the majority of recent nutrition research has focused on the general effects of nutrients on IBD, with little attention given to the advantages and negative aspects of individual foods and dietary combinations. To cover these shortcomings, we surveyed the benefits and drawbacks of typical foods and their chemical compositions on intestinal pathophysiology by comparing nutrients existing in the foods in Eastern and Western countries. Moreover, for Eastern and Western patients with IBD, we innovatively propose a 3-step dietary recommendation based on modified customary eating habits, including lowering the triggering foods, modifying dietary advice to control disease progression, and improving surgery prognosis.