Impact of dietary regimen on the duration of cow's milk allergy: a random allocation study.

Background: The impact of diet on cow's milk allergy (CMA) duration and whether exposure to residual amounts of cow's milk protein influences the onset of tolerance are unknown.

Objective: To prospectively assess the dietary factors influencing disease duration in a randomized cohort.

Methods: We randomly switched the formula of symptomatic patients from the Milan Cow's Milk Allergy Cohort to one of three treatment groups according to the quarterly rotation of rice hydrolysate formula, extensively hydrolysed cow's milk formula and soy-based formula. In this intention-to-treat, randomized analysis, a hazard ratio (HR) estimation model was used to analyse dietary impact on disease duration.

Results: Seventy-two children aged a mean of 14.1+/-8.6 months at diagnosis were followed up for a median of 26 months. Fifty-one reached tolerance at a mean of 34.1+/-15.2 months. The mean duration of disease was 40.2+/-4.8 months with milk hydrolysate, 24.3+/-3.6 months with rice and 24.3+/-2.6 months with soy. Dietary choice independently predicted shorter duration of disease [adjusted HRs 3.09 (P=0.007) for rice, 2.54 (P=0.02) for soy, both against milk hydrolysate]. In 50 children not co-sensitized to soy, diet choice impacted the duration of disease more strongly [adjusted HRs 8.02 (P=0.006) for rice, 6.53 (P=0.015) for soy, both against milk hydrolysate].

Discussion: Patients not exposed to cow's milk protein residue achieve cow's milk tolerance earlier than patients who follow an extensively hydrolysed cow's milk diet. This may be due to residual antigenicity in hydrolysed milks. As the effect of dietary intervention is stronger in patients not sensitized to soy, we infer that when atopic disease has progressed to multiple sensitizations, the elimination of allergenic exposure may not be sufficient to reduce the duration of CMA.