Crohn’s disease (CD) and ulcerative colitis (UC) are two chronic inflammatory diseases of the gastrointestinal tract, collectively known as inflammatory bowel disease (IBD). Each is distinct in its presentation and course of disease, and both are chronically relapsing illnesses. Despite histological differences between the two diseases, dietary therapy (with the exception of known efficacy of enteral therapy and CD) has often been similar for both [1], involving options that include increased fluids, avoidance of fatty foods, dietary fiber, and dairy products if lactose intolerant. Others have ingested nothing by mouth for a period of time, and used tube feeding with elemental diets [2]. Presently, an alteration of the intestinal microbiome is believed to be a major factor in the pathogenesis of IBD, and this change provides a possible pathway for dietary manipulations of the microbiome that may reduce inflammation in these conditions [3, 4].

The goals for treatment of IBD are the induction of remission, maintenance of remission, reduction in the need for long-term use of corticosteroids, improved quality of life, and improved prognosis. The mainstays of current treatment comprise of anti-inflammatory agents including corticosteroids, immunomodulators, and biologic agents. There are surgical options including colectomy, which while curative for patients with UC, can result in a pouch or end ileostomy in approximately 30% of patients [5]. Neither of these surgical options is without complications and up to 70% of patients with a pouch may develop pouchitis [6, 7]. An even higher percentage of CD patients need surgery, with upward of 80% of patients requiring surgical resection that is not necessarily curative [5].

Until recently, the investigation of nutritional approaches in treating the diseases have been largely limited to the use of enteral and total parenteral nutrition with the aim of providing bowel rest [8, 9]. Dietary whole food recommendations for CD and UC are poorly developed, even though patients often ask for advice with their diet [10]. To prepare clinicians for the complex management of patients with IBD, Brown et al. published dietary guidelines to fill this gap, [2] compiling a summary of suggestions from reputable organizations, concluding that no specific diet currently exists for patients with IBD. Most dietary guidelines, though varied in scope and complexity, indicate that limiting lactose, excess fat, excess carbohydrates, and reducing fiber in the diet is necessary, particularly during flares of disease [2]. Mineral and vitamin supplementation may or may not assist with nutrient deficiencies and malabsorption. In addition, many patients also experience other food intolerances [11, 12]. To provide a dietary therapy approach addressing nutrient adequacy, malabsorption issues, and symptoms, we developed the IBD-Anti-Inflammatory Diet, or IBD-AID [13–15]. The diet was offered to patients who were refractory to pharmacological therapy, or treatment was not as effective as desired. This is a retrospective case series to demonstrate the beneficial effects of the IBD-AID on a small number of patients.

Out of the original 40 patients, 37 were seen by the dietitian. Of those, 13 did not attend any follow-up visits. Three had an ambivalent or negative response to the diet, and 24 had a good or very good response to the diet, as measured by self-report of symptoms and compliance with the diet through food records. Of the patients reporting improvement, they were all able to reach greater than 70% compliance to the diet. Of the 3 patients (2 with UC, 1 with CD) with ambivalent or negative response, 2 were diagnosed with Clostridium Difficile (C-diff), and the other (UC) patient’s response is unattributable.

The 11 patients, who met eligibility by IRB and had complete data, underwent medical record review: 8 have CD, 3 have UC, and age range was 19–70 years (see Table 1). All patients used the diet for at least 4 weeks. Before the dietary intervention, 7 patients (64%) had 1 or more drug treatment failures, meaning they had adverse side effects, the medication had no effect, or the medication had become ineffective over time. After using the IBD-AID, which was the only additional intervention added, all (100%) of the patients worked with their gastroenterologists to downscale their medication regimen and all (100%) of the patients had their IBD symptoms reduced. Of the CD patients, the baseline HBI averaged 11 (range 1 to 20), and after dietary intervention, the HBI averaged 1.5 (range 0 to 3). The UC patients had a mean baseline score of MTLWSI of 7 (range 6 to 8, with one patient unable to report baseline), and their mean follow-up score was 0. The mean decrease in the HBI was 9.5 and the mean decrease in the MTLWSI was 7 (Table 1).

Our data suggest that at least some of our patients with inflammatory bowel disease can benefit from the use of the IBD-AID, particularly in terms of reducing symptomatology and consequently a reduction in the use of medication. A portion (33%) of patients who were offered the diet declined initiation, and of those who decided to participate, many encountered behavioral and intellectual barriers that are to be expected with any comprehensive change in dietary lifestyle. The assistance of a partner also trained in the IBD-AID was clearly beneficial [31]. In the current study, due to small numbers of patients and the case series study design, we were unable to confirm our hypothesized mechanisms of action by examining the impact of the IBD-AID on the intestinal microbiome. However, as deep sequencing and other techniques for defining the microbiome become less expensive this may prove an objective measure of the benefit not only of the IBD-AID, but other diets as well; particularly if the microbiome can be shown to normalize as mucosal healing occurs.

Studies have suggested that IBD results from an inappropriate activation of the mucosal immune system in a genetically susceptible host [30]. The intraluminal gut flora appears to play a role in the inflammatory response and pathogenesis of IBD [32]. A study of patients with UC revealed that bifidobacteria populations are approximately 30 times lower than that of healthy individuals, indicating a dysbiosis that may potentially alter inflammatory responses [33, 34]. However, it is unclear whether the change in flora is primary, or secondary to the disease. Diet has been shown to influence the balance of the intestinal flora [35]; therefore, it is conceivable that altering the diet can impact the inflammatory response [36].

Mucosal healing potential is another aspect of the IBD-AID [37]. Minimizing irritants, while increasing nutrient delivery in a phased manner, (see Table 2) according to patient symptomology is an important consideration to the diet. This is derived from the success of treatment of IBD with tube feeding as opposed to simply nothing by mouth (NPO) [38]. Nutritional deficiencies can result from reduced oral intake, malabsorption, medication side effects and systemic inflammation due to active disease [38, 39]. In CD, the natural history of disease progression is a significant increase in complicated disease (from <29% patients at initial diagnosis having stricturing or penetrating disease to 88% of patients at 20 years) [40].

The Specific Carbohydrate Diet (SCD, from which the IBD-AID was derived and augmented) was developed by Dr. Sydney Valentine Haas and Dr. Merrill P Hass for the treatment of celiac disease in the mid-20^th century [41], and was later popularized as a treatment for IBD via the internet and lay population [42]. This nutritional regimen eliminates all grains, and encourages ingestion of probiotics in the form of homemade yogurt. The IBD-AID diet is not designed around avoidance of gluten, and strives to address other micro- and macronutrients not addressed in the SCD. The food supply, processing and transport of foods have changed dramatically since the inception of the SCD. The IBD-AID also modifies fatty acids, specifically decreasing the total and saturated fats and eliminating hydrogenated oils, and encouraging the increased intake of foods with omega-3 fatty acids. The IBD-AID also differs from the SCD with the inclusion of oats, since oats (and possibly other fermentable grains that provide a substrate for probiotics) [43] appear to be well tolerated and indeed are useful in regulation of bowel frequency and consistency [44].

The IBD-AID is a dietary pattern for which the mechanism and efficacy have yet to be elucidated. Poorly digested complex carbohydrates (even those with defined pre-biotic properties) may lead to bacterial overgrowth and bowel injury with increased intestinal permeability. The waste products of fermentation of undigested carbohydrates include methane, carbon dioxide, hydrogen, lactic and acetic acid, which are all gastrointestinal irritants. The carbohydrates allowed on the original diet are monosaccharides, that is, they have a molecular structure which allows intestinal absorption without additional enzymatic degradation. Improvement of nutritional status and alteration in ileo-colonic flora by certain foods is theorized to lead to decreased mucosal inflammation [2, 45]. There has been an increase in publications over the past ten years with regard to food-based strategies used to alter the intestinal microflora as an alternative or adjunctive therapy for the treatment of IBD. The altered bacteria in the microbiome of IBD patients is said to drive inflammatory responses, [21, 24] and there are a growing number of articles linking particular foods that influence the intestinal microbiome, by withholding certain foods that are not well tolerated by patients, or introducing others that can improve symptoms [46].

The dietary pattern of the IBD-AID is carefully oriented to decrease inflammation [14, 15] and improve nutritional status, and thought to maintain a beneficial intestinal bacterial balance; however, this has yet to be proven by rigorous scientific examination. The current case series is promising, but must be followed with rigorous research and standardized study design to detect molecular markers of inflammatory and histo-pathological changes to correlate with clinical outcomes.

The IBD-AID can be difficult and restrictive diet; with adherence largely dictated by personal motivation, support from family and friends, and skills in the kitchen and the marketplace. Consultation and continued support from a knowledgeable dietitian may enhance compliance with the diet.

Physicians are not provided with specific dietary treatments to offer their IBD patients [47], and recommendations for normal diet are often based upon a philosophy of “if it hurts, don’t do it”. This case series serves to highlight the importance of dietary manipulation as an adjunct to the limited existing management options for IBD. The study of the IBD-AID would benefit from the rigorous analysis provided by a randomized clinical trial, with evaluation of mucosal healing and assessment of change in gut flora to examine the exact mechanism(s) of benefit.