Can fecal calprotectin levels be used to monitor infant milk protein allergies?

BACKGROUND: Milk protein allergy is one of the most common food allergies in infants. We aimed to test whether fecal calprotectin can be used to monitor food allergies in infants by comparing the fecal calprotectin levels in infants with a milk protein allergy before and after an intervention treatment. METHODS: The study was designed as a prospective case–control trial. Stool samples were collected at follow-up, and the concentration of fecal calprotectin was determined using an enzyme-linked immunosorbent assay. The infant’s weight and length were measured. RESULTS: The allergic group comprised 90 milk-allergic infants (41 boys, 49 girls), and the nonallergic group comprised 90 nonallergic infants (51 boys, 39 girls). Compared with the fecal calprotectin level in the nonallergic group (median: 141 μg/g), that in the allergic group (median: 410 μg/g) was significantly higher (z = − 9.335, p < 0.001). After two dietary interventions and treatments, the fecal calprotectin levels of the infants with a milk protein allergy at the first (median: 253 μg/g) and second follow-up visits (median: 160 μg/g) were significantly lower than those before the intervention (z = − 7.884, p < 0.001 and z = − 8.239, p < 0.001, respectively). The growth index values (LAZ and WAZ) of the infants with a milk protein allergy at the first and second follow-up visits were significantly higher than those before dietary intervention (p < 0.05). Fecal calprotectin was negatively and significantly correlated with the WLZ and WAZ at the second follow-up visit (Spearman’s rho = − 0.234, p = 0.01 and Spearman’s rho = − 0.193, p = 0.03, respectively). CONCLUSION: The level of fecal calprotectin in infants with a milk protein allergy decreased after dietary intervention and seems to be a promising biological indicator for monitoring intestinal allergies.