Impact of soymilk consumption on 2,4-dinitrofluorobenzene-induced contact hypersensitivity and gut microbiota in mice

Soymilk is rich in phytochemicals such as soy isoflavones (SIs) and soyasaponins (SSs). Dietary SIs and SSs display inhibitory effects on contact hypersensitivity (CHS), which was reported in a mouse model for allergic contact dermatitis (ACD); however, the beneficial effects of soymilk consumption on CHS remain unknown. Here, we studied the effects of drinking soymilk on CHS and gut microbiota. Soymilk consumption attenuated ear oedema and swelling, decreased the infiltration of Gr-1-positive cells into ear tissues, and reduced the production of chemokine (C-X-C motif) ligand 2 and triggering receptor expressed on myeloid cells-1 in ear tissues. The analysis of bacterial 16S ribosomal RNA gene sequences indicated that CHS caused changes in the gut microbiota structure and that consuming soymilk reduced these changes. These results suggest that soymilk consumption may be of therapeutic value for patients with ACD and may help control the balance of intestinal microbiota.