A New Perspective on the Role of Lactobacillus acidophilus in the Prevention and Treatment of Allergic Diseases and Cancer

The aim of this review is to provide a narrative analysis of the role of Lactobacillus acidophilus as an active modulating factor in the prevention and treatment of cancer and allergic diseases. The paper discusses the molecular, metabolic, and bionanotechnological mechanisms of Lactobacillus acidophilus’s anticancer and immunomodulatory effects, which define this probiotic as an essential component of modern natural and functional medicine. A narrative review of the scientific literature was conducted, mainly from 2019–2026, focusing on the results of in vitro studies and studies on preclinical in vivo models, which analyzed the effect of live L. acidophilus strains, tyndallized bacteria (paraprobiotics) and cell-free supernatant from L. acidophilus cultures on, among others, immune system signaling pathways, tissue cytokine profile, and the integrity of the gastrointestinal epithelial cell barrier (enterocytes). Results indicate that L. acidophilus exerts significant antiallergic, antiproliferative, and proapoptotic effects against many types of cancer. Among other aspects, the ability of L. acidophilus to stimulate the production of anticancer exopolysaccharides and short-chain fatty acids, which directly influence the functioning of immune cells, is covered. The article thoroughly explains the immunomodulatory effects of L. acidophilus and the ability of this probiotic to regulate cytokine profiles, which helps promote an anti-inflammatory environment crucial for maintaining intestinal homeostasis. The article also discusses the direct interaction of L. acidophilus with immune cells, such as dendritic cells and macrophages, which leads to their activation and subsequent influence on the differentiation of T lymphocytes, which play a key role in the regulation of immune processes and in the development of immune tolerance. L. acidophilus is a universal mediator of immunological and metabolic homeostasis. Its ability to synergize with conventional therapies (chemotherapy, oncolytic virotherapy) and its innovative applications in the creation of postbiotics and paraprobiotics may provide a new approach to the treatment of inflammatory, allergic, and neoplastic diseases. Further clinical studies are necessary to assess the efficacy, safety, and optimal dose of this probiotic, which are essential for the widespread use of L. acidophilus in human therapy.