Nutraceuticals as Modulators of Immune Function: A Review of Potential Therapeutic Effects

Dietary supplementation with nutraceuticals can promote optimal immune system activation, modulating different pathways that enhance immune defenses. Therefore, the immunity-boosting effects of nutraceuticals encompass not only immunomodulatory but also antioxidant, antitumor, antiviral, antibacterial, and antifungal properties, with therapeutic effects against diverse pathological conditions. However, the complexity of the pathways that regulate the immune system, numerous mechanisms of action, and heterogeneity of the immunodeficiencies, and subjects treated make their application in the clinical field difficult. Some nutraceuticals appear to safely improve immune system function, particularly by preventing viral and bacterial infections in specific groups, such as children, the elderly, and athletes, as well as in frail patients, such as those affected by autoimmune diseases, chronic diseases, or cancer. Several nutraceuticals, such as vitamins, mineral salts, polyunsaturated omega-3 fatty acids, many types of phytocompounds, and probiotic strains, have the most consolidated evidence in humans. In most cases, further large and long-term randomized clinical trials are needed to confirm the available preliminary positive data.