Cow's milk allergy is associated with changes in urinary organic acid concentrations

Cow's milk allergy (CMA) is the most common form of food allergy affecting 2.5% of children, but the diagnosis is often difficult. Both intestinal microbiota and barrier function seem to be disturbed in patients with food allergies, and administration of probiotics has been shown to normalize intestinal microbiota and alleviate symptoms. We hypothesized that the differences in intestinal metabolic activity and permeability could lead to detectable changes in the end-products of metabolism in patients with CMA. This could offer new diagnostic possibilities. The urinary concentrations of 37 organic acids were studied by a mass spectrometry-based method in 35 infants aged under 1 yr with atopic eczema, 16 of them having CMA diagnosed with a double-blind placebo-controlled food challenge test. The control group consisted of the remaining 19 infants with only atopic eczema. In a second study, Lactobacillus rhamnosus GG (LGG) or placebo was administered to the infants with CMA for 4 wk and the urinary organic acids were analysed again. CMA patients and patients with only atopic eczema had statistically significant differences in urinary concentrations of hydroxybutyrate (p < 0.001); adipate and isocitrate (p < 0.01 for both); homovanillate, suberate, tartarate, 3-indoleacetate and 5-hydroxyindoleacetate (p < 0.05 for all). These concentrations did not change significantly following LGG administration to the CMA patients, but a trend towards the control group was seen. Thus, CMA is associated with changes in some urinary organic acid levels. These differences between atopic infants with and without CMA could be investigated as a novel approach for CMA diagnosis.