Plasma glucagon-like peptide 1 and peptide YY levels are not altered in symptomatic fructose-sorbitol malabsorption

Perceived food hypersensitivity: a review of 10 years of interdisciplinary research at a reference center

Perceived food hypersensitivity is a prevalent, but poorly understood condition. In this review article, we summarize narratively recent literature including results of our 10 years' interdisciplinary research program dealing with such patients. The patients (more than 400) included in our studies were all adults referred to a university hospital because of gastrointestinal complaints self-attributed to food hypersensitivity. Despite extensive examinations, food allergy was seldom diagnosed. The majority of the patients fulfilled the diagnostic criteria for irritable bowel syndrome. In addition, most suffered from several extra-intestinal health complaints and had considerably impaired quality of life. However, psychological factors could explain only approximately 10% of the variance in the patients' symptom severity and 90% of the variance thus remained unexplained. Intolerance to low-digestible carbohydrates was a common problem and abdominal symptoms were replicated by carbohydrate ingestion. A considerable number of patients showed evidence of immune activation by analyses of B-cell activating factor, dendritic cells and "IgE-armed" mast cells. Multiple factors such as immune activation, disturbed intestinal fermentation, enteric dysmotility, post-infectious changes and "local" allergy in the gut as well as psychological disturbances may play a role in the pathophysiology of perceived food hypersensitivity. Hence, our results support the view that management of these patients should be interdisciplinary.

Intestinal fermentation in patients with self-reported food hypersensitivity: painful, but protective?

PURPOSE

Enterometabolic disturbances may cause meal-related symptoms. We performed a functional evaluation of the intestinal microflora in patients with unexplained, self-reported food hypersensitivity by measuring fecal short-chain fatty acids (SCFAs).

PATIENTS AND METHODS

Thirty-five consecutive patients with self-reported food hypersensitivity and 15 healthy volunteers of similar age, gender, and body mass index collected all feces for 72 hours. Fecal concentrations of acetic, propionic, n-butyric, i-butyric, n-valeric, i-valeric, n-caproic, and i-caproic acids were analyzed by gas-liquid chromatography. Concentrations and excretions (output) of SCFAs in patients and controls were compared and related to gastrointestinal symptoms.

RESULTS

Despite nonsignificant differences between patients and controls for both total and individual SCFA concentrations and excretions, n-butyric acid comprised a higher (P = 0.035) and acetic acid a lower (P = 0.012) proportion of total SCFA in patients compared to controls. There were no significant correlations between symptom scores and concentrations or excretions of individual or total SCFAs, but the proportion of n-butyric acid was significantly higher in patients with severe symptoms compared to patients with moderate symptoms (P = 0.016).

CONCLUSION

The results indicate an enterometabolic disturbance in patients with self-reported food hypersensitivity. Higher proportions of n-butyric acid may be related to abdominal symptom generation, but may also protect against organic bowel disease. Further studies are needed to clarify these aspects.

Carbohydrate intolerance in patients with self-reported food hypersensitivity: comparison of lactulose and glucose

OBJECTIVE

Malabsorption of low-digestible carbohydrates is physiological, but poorly tolerated in some patients. We investigated symptom anticipation and microbial fermentation as possible mechanisms of carbohydrate intolerance in patients with self-reported food hypersensitivity.

MATERIAL AND METHODS

In a randomized, double-blind, cross-over study, 27 consecutive patients with unexplained, self-reported food hypersensitivity were given 10 g lactulose and 10 g glucose (placebo). Symptoms and pulmonary excretion of hydrogen and methane were assessed. Short-chain fatty acids (SCFAs), lactate and prostaglandin E(2) (PGE(2)) were analyzed in rectal dialysis fluid, and compared to dialysates from nine healthy volunteers.

RESULTS

Post-lactulose symptom scores were correlated with habitual symptom scores (r = 0.6, p = 0.001), significantly higher than post-glucose symptom scores (p = 0.01) and significantly higher in patients than controls (p = 0.0007). Levels of SCFAs, lactate and PGE(2) in rectal dialysates were not significantly different after lactulose and glucose, or between patients and controls. Hydrogen excretion was not correlated with symptom scores.

CONCLUSIONS

The findings suggest that self-reported food hypersensitivity is related to microbial fermentation of malabsorbed carbohydrates and not to symptom anticipation solely. Levels of SCFAs, lactate and PGE(2) in rectal dialysates could not explain the fermentation-associated hypersensitivity.