Single-cell RNA sequencing reveals that kimchi dietary intervention modulates human antigen-presenting and CD4⁺ T...

Kimchi, a traditional Korean fermented food, is recognized for its metabolic benefits; however, its effects on human immune function remain poorly defined. In this study, we performed single-cell RNA-seq on peripheral blood mononuclear cells from 13 overweight adults using a paired pre/post design in a 12-week randomized, double-blind, placebo-controlled trial. The participants consumed a placebo, spontaneously fermented kimchi powder, or starter culture-fermented kimchi powder. Kimchi enhanced intercellular signaling mediated by antigen-presenting cells, increased antigen uptake, and promoted the upregulation of MHC class II-related genes through the JAK/STAT1-CIITA axis. Single-cell trajectory analysis revealed accelerated CD4⁺ T cell differentiation toward effector and regulatory phenotypes, whereas CD8⁺ T cells, B cells, and NK cells remained stable, indicating preserved systemic immune homeostasis. In summary, 12 weeks of kimchi dietary intervention enhanced antigen presentation and remodeled CD4⁺ T cells without broad systemic activation, providing single-cell evidence of kimchi-induced dietary immunomodulation in humans. The clinical trial was registered at ClinicalTrials.gov ( https://www.clinicaltrials.gov/ ) under the identifier NCT05898802.