The gut microbiome plays an important role in supporting a healthy immune response. Commensal bacteria and other microbes aid in protecting against potentially pathogenic microbes and synthesize metabolites that secrete immunomodulatory components. The microbes and their metabolites also interact with the immune system to maintain a balance between adequate preparation for protection and hypersensitivity or overreactions that could contribute to chronic inflammation and other problems. Probiotics such as Lactobacillus rhamnosus GG (LGG) that are acid and bile resistant, have good growth characteristics, and adhere well to the epithelium may contribute to microbial balance in support of the immune system.

Research has identified several potential immunomodulating properties of LGG, including stimulating antibody production and improving phagocytic activity of leucocytes. LGG may also inhibit the production of tumor necrosis factor-alpha (TNF-α) and nuclear factor-kappa B (NF-κB) and promote the production of interferon-gamma (IFN-γ), interleukin (IL)-12, and IL-18. Studies have shown LGG also supports the maintenance of homeostasis in the mucosa by increasing the release of cyclooxygenase-2 (COX-2)–mediated prostaglandin E2 (PGE2). Prostaglandins support the regulation of epithelial cell proliferation and intestinal permeability. High levels can lead to chronic inflammation and therefore, maintaining balance is important. LGG-soluble mediators (LSM), which are LGG components, have been found to influence adaptive immune responses by supporting the creation of dendric cells with an active T-cell stimulatory capacity. These cells can induce both T helper type 1 (Th1) cells and regulatory T cells, which may support allergic diseases.

Clinical studies have demonstrated that these actions may support normal immune function. In a randomized controlled trial, children with acute rotavirus infections who supplemented with LGG experienced an increase in their immunoglobulin G (IgG) response. The treatment group also had a reduction in subsequent diarrheal episodes and improved intestinal permeability. In a meta-analysis of randomized controlled trials in children, supplementing with LGG alone or with additional probiotic strains was associated with a reduced risk of upper respiratory tract infections and a reduced incidence of acute otitis media compared to the controls.

The complexity of the immune system requires many nutrients and compounds to run optimally. Maintaining a healthy gut microbiome provides many components that maintain normal immune function. Individuals who require additional support to increase the abundance of commensal bacteria compared to potentially pathogenic bacteria may find probiotic supplementation beneficial.*

By Kendra Whitmire, MS, CNS