Evaluation the effect of elimination diet on intestinal mucus barrier in infants diagnosed with Cow's milk protein allergy

Cow's milk protein allergy (CMPA) is the most common food allergy in infants and young children, for which elimination diet is the only effective treatment. Allergic disease originates in the intestinal barrier, where mucin 2 (MUC2) and secretory Immunoglobulin A (sIgA) are critical for defence. This study included infants with non-IgE mediated CMPA in the case group and healthy infants in the control group. The aim was to assess MUC2 and sIgA levels in both groups and to evaluate the effects of the elimination diet on these parameters, as well as on growth, development, and nutritional status. The study was included 17 infants with CMPA and 17 healthy infants under 26 weeks of age and their mothers. Data were collected at two time points: at the beginning and end of the elimination diet for case group, 3 months after recruitment for control group. A structured questionnaire was used to collect socio-demographic and health information. Growth and development were assessed by anthropometric measurements, and stool samples were collected to analyze MUC2 and sIgA levels. Three-day dietary records were obtained from both mothers and infants, and maternal dietary compliance and infant feding status were assessed. Infants' clinical symptoms were evaluated using the Cow's Milk Related Symptom Score (CoMiSS). The mean duration of the elimination diet in the case group was 1.9±0.79 months. At the end of the study, body weight, height and weight-for-age in the case group were lower than in the control group (p<0.05). Only the control group showed a significant increase (p<0.05). The CoMiSS score was significantly higher in the case group at baseline and the end of the study but decreased significantly with the elimination diet (p<0.05). After the elimination diet, the case group had lower energy, protein, saturated fat, vitamin E, vitamin B1, vitamin B2, vitamin B3, vitamin B6, folate, calcium and phosphorus, while carbohydrate intake was higher (p<0.05). At baseline, MUC2 levels were 4.07 (1.17) ng/mL in the case group and 3.45 (1.09) ng/mL in the control group (p<0.05). Following the elimination diet, MUC2 levels in the case group significantly decreased to 2.95 (1.48) ng/mL (p<0.05). sIgA levels remained similar between groups throughout the study (p>0.05). In conclusion, elimination diets may cause growth and nutritional deficiencies, it's important to follow up. In addition, CMPA increases MUC2 levels and the mucus barrier structure of infants with CMPA may become similar to that of healthy individuals on elimination diet.