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 Firmicutes, Bacteroidetes, and Lactobacilli 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.