Effects of low pseudoallergen diet on urticarial activity and leukotriene levels in chronic urticaria

Pseudoallergens and leukotrienes (LTs) may have a role in chronic urticaria (CU). The aim of our study is to evaluate the response to the low pseudoallergen diet therapy in patients with CU and the change in LT levels in diet responsive and non-responsive patients. 34 patients with CU were put on diet for 4 weeks. All patients kept a daily score sheet of pruritus and whealing symptoms. The urticarial activity score (UAS) of each patient was calculated with the sum of pruritus and wheal score. The sum score of the first 7 consecutive days (UAS7-first week) and last 7 days (UAS7-fourth week) were used to compare the clinical outcome of the diet. A reduction of a parts per thousand yen50% in UAS7-fourth week compared to UAS7-first week was considered as "response". Urinary LTE4 (uLTE4) level of each patient was measured at baseline and after the 4 week of diet therapy. 14 of the patients (41.2%) were responsive to diet therapy. Baseline uLTE4 levels were similar between responsive and non-responsive patients (P = 0.540). Second uLTE4 levels (after the 4 week of diet therapy) were significantly lower in responsives than in non-responsive patients (P < 0.001). Second uLTE4 levels of responsives were significantly lower than the baseline values (P = 0.019), whereas this was not significant for non-responsives (P = 0.070). There was a significant correlation between the change in uLTE4 levels and the change in mean urticarial activity scores (r = 0.554, P = 0.001) in the whole study population. In conclusion, low pseudoallergen diet helps to reduce the urticarial activity in CU. The change in urticarial activity correlates with the change in LT levels.