Lactic Acid Alleviates Cow’s Milk Allergy by Regulating Regulatory T Cells and Intestinal Microbiota

Cow's milk allergy (CMA) is common in early childhood, and the incidence is increasing. As a precursor of short-chain fatty acids, lactic acid holds great potential in the treatment of CMA. The β-lactoglobulin-induced food allergy mice model was established, and lactic acid was added at different times to explore its antiallergic activity. The LA-Pre group (lactic acid administered before sensitization) significantly decreased the levels of immunoglobulin (Ig) E and IgG1, inhibiting Th2 differentiation and the production of interleukin (IL)-4 while promoting the differentiation of regulatory T cells. However, the LA-Post group (lactic acid administered after sensitization) reduced only the levels of IgE and IL-4. Additionally, the LA-Pre group demonstrated significant regulation of the abundance of intestinal microbiota, influencing the numbers of <i>Firmicutes</i>, <i>Bacteroidetes</i>, and <i>Lactobacilli</i> in the intestinal tracts. Taken together, the antiallergic activity of lactic acid was examined providing a novel strategy for the prevention and treatment of CMA.