Liver-centric strategies for immune enhancement: an evidence-based review of the gut–liver axis, metabolism, lifestyle, and vaccination

Purpose: Although the liver is widely recognized as the body’s primary metabolic organ, it also functions as a major immunometabolic interface between the gut and systemic circulation. Continuous exposure to gut-derived antigens requires a tightly regulated balance between immune tolerance and immune activation. Therefore, “immune enhancement” should be understood as optimization of the hepatic immune-metabolic network rather than nonspecific stimulation of immune responses. This review summarizes evidence-based strategies for supporting hepatic and systemic immunity in patients with chronic liver disease and in the general population.Current concepts: Hepatic immunity is regulated largely by innate immune components, including Kupffer cells, liver sinusoidal endothelial cells, and Toll-like receptor signaling. The gut–liver axis is a major pathway of immune regulation; probiotics and postbiotics may strengthen the intestinal barrier and reduce lipopolysaccharide-driven inflammation. Nutrients such as branched-chain amino acids, vitamin D, zinc, and selenium support immune-cell function and may help attenuate immunosenescence. Silymarin and melatonin may reduce oxidative stress and modulate nuclear factor κB- and transforming growth factor-β1-mediated inflammatory and fibrotic pathways. Regular moderate exercise and adequate sleep also contribute to immune regulation through anti-inflammatory myokines and circadian stabilization. In cirrhosis-associated immune dysfunction, vaccination against hepatitis A and B, pneumococcus, influenza, and coronavirus disease 2019 is essential for reducing the risk of infection and decompensation.Discussion and conclusion: Maintaining liver health is integral to systemic immune function. A liver-centered strategy that combines gut microbiome modulation, appropriate nutritional supplementation, regular exercise, adequate sleep, and vaccination is preferable to unverified “immune-boosting” supplements.