Adverse reactions to foods

Postprandial symptoms in disorders of gut-brain interaction and their potential as a treatment target

Postprandial, or meal-related, symptoms, such as abdominal pain, early satiation, fullness or bloating, are often reported by patients with disorders of gut-brain interaction, including functional dyspepsia (FD) or irritable bowel syndrome (IBS). We propose that postprandial symptoms arise via a distinct pathophysiological process. A physiological or psychological insult, for example, acute enteric infection, leads to loss of tolerance to a previously tolerated oral food antigen. This enables interaction of both the microbiota and the food antigen itself with the immune system, causing a localised immunological response, with activation of eosinophils and mast cells, and release of inflammatory mediators, including histamine and cytokines. These have more widespread systemic effects, including triggering nociceptive nerves and altering mood. Dietary interventions, including a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols, elimination of potential food antigens or gluten, IgG food sensitivity diets or salicylate restriction may benefit some patients with IBS or FD. This could be because the restriction of these foods or dietary components modulates this pathophysiological process. Similarly, drugs including proton pump inhibitors, histamine-receptor antagonists, mast cell stabilisers or even tricyclic or tetracyclic antidepressants, which have anti-histaminergic actions, all of which are potential treatments for FD and IBS, act on one or more of these mechanisms. It seems unlikely that food antigens driving intestinal immune activation are the entire explanation for postprandial symptoms in FD and IBS. In others, fermentation of intestinal carbohydrates, with gas release altering reflex responses, adverse reactions to food chemicals, central mechanisms or nocebo effects may dominate. However, if the concept that postprandial symptoms arise from food antigens driving an immune response in the gastrointestinal tract in a subset of patients is correct, it is paradigm-shifting, because if the choice of treatment were based on one or more of these therapeutic targets, patient outcomes may be improved.

Naturally-occurring dietary salicylates in the genesis of functional gastrointestinal symptoms in patients with irritable bowel syndrome: Pilot study

Background and Aim

An elimination‐rechallenge dietary approach targeting naturally‐occurring bioactive chemicals has been proposed to alleviate functional gastrointestinal symptoms. A major focus of this approach is salicylates. This study aimed to address the potential role of dietary salicylates in the induction of symptoms in patients with irritable bowel syndrome (IBS).

Methods

A pilot, double‐blind, randomized, cross‐over trial of 2‐week low‐ versus high‐salicylate diets (6.6 and 27.9 g/day salicylate, respectively) was undertaken. All foods were provided containing minimal quantities of other potential food triggers. Gastrointestinal and extraintestinal symptoms were measured daily using a 100‐mm visual‐analogue‐scale.

Results

Ten participants with IBS completed the study, including one with known aspirin‐sensitivity. Overall, no differences in symptoms were observed (P = 0.625; Friedman test). However, clear symptom provocation was seen in the aspirin‐sensitive participant, with all abdominal symptoms and tiredness worsening during the high‐salicylate diet. A similar trend was seen in another participant, where abdominal symptoms gradually worsened during the high‐salicylate diet.

Conclusions

These results provide some evidence that food‐related salicylates may influence the genesis of symptoms in a subset of patients with IBS. A larger cohort is needed to determine the incidence of salicylate‐sensitivity and further evaluate the diet as a potential therapeutic target.

The protocol was registered at www.anzctr.org.au (ACTRN12620001250921).

Restriction and Elimination Diets in ADHD Treatment

Food elimination diets are defined and the history of their investigation in relation to attention-deficit/hyperactivity disorder (ADHD) is reviewed. After noting that a consensus has emerged that an elimination diet produces a small but reliable aggregate effect, the present review provides updated quantitative estimates of effect size and clinical response rates to elimination diets. It then highlights key issues that require research attention, in particular characterization of dietary responders. Finally, because some children may benefit, clinical guidelines at the present state of knowledge are summarized. It is concluded that updated trials of elimination diets are sorely needed for ADHD.

Are adverse food reactions linked to irritable bowel syndrome?

OBJECTIVE

We undertook to determine whether adverse food reactions play a role in irritable bowel syndrome (IBS).

METHODS

A systematic review of the literature using Medline (1980-1996), targeting IBS and adverse food reactions, was performed. All clinical trials whereby dietary exclusion was followed by food challenge were selected. Each study was reviewed using a structured format to examine methodological issues and study outcomes.

RESULTS

Of the seven studies included, the positive response to an elimination diet ranged from 15% to 71%; double-blind placebo-controlled challenges identified problem foods in 6% to 58% of cases. Milk, wheat, and eggs were most frequently identified to cause symptom exacerbation; of the foods identified the most common trait was a high salicylate content. Foods high in amines were also identified. Studies of diarrhea-predominant IBS identified a higher percentage of adverse food reactions. However, all studies had major limitations in their trial designs, including inadequate patient selection, appropriateness of--and duration of--exclusion diets, and methods of food challenge.

CONCLUSION

Whether adverse reactions to foods are a key factor in exacerbating IBS symptoms or whether dietary manipulation is a valid treatment option is unclear. Carefully designed controlled clinical trials are now needed to specifically test the potential role of adverse food reactions in diarrhea-predominant IBS.