Plant-Derived Nutraceuticals and Immune System Modulation: An Evidence-Based Overview

Abstract

Immunomodulators are agents able to affect the immune system, by boosting the immune defences to improve the body reaction against infectious or exogenous injuries, or suppressing the abnormal immune response occurring in immune disorders. Moreover, immunoadjuvants can support immune system acting on nonimmune targets, thus improving the immune response. The modulation of inflammatory pathways and microbiome can also contribute to control the immune function. Some plant-based nutraceuticals have been studied as possible immunomodulating agents due to their multiple and pleiotropic effects. Being usually more tolerable than pharmacological treatments, their adjuvant contribution is approached as a desirable nutraceutical strategy. In the present review, the up to date knowledge about the immunomodulating properties of polysaccharides, fatty acids and labdane diterpenes have been analyzed, in order to give scientific basic and clinical evidence to support their practical use. Since promising evidence in preclinical studies, limited and sometimes confusing results have been highlighted in clinical trials, likely due to low methodological quality and lacking standardization. More investigations of high quality and specificity are required to describe in depth the usefulness of these plant-derived nutraceuticals in the immune system modulation, for health promoting and disease preventing purposes.

Does Flavonoid Consumption Improve Exercise Performance? Is It Related to Changes in the Immune System and Inflammatory Biomarkers? A Systematic Review of Clinical Studies since 2005

“…It is well-established that moderate physical activity enhances immune functions [ 32 , 33 , 34 ], but intense exercise induces inflammation, alters phagocytic and cytotoxic functions, decreases mucosal IgA, and increases the susceptibility to infections, especially URTI [ 40 , 42 ]. In recent years, flavonoids have shown immunomodulatory properties in both animal and human studies [ 139 , 140 , 141 , 142 ]. In fact, a recent review [ 142 ] demonstrated that flavonoid consumption decreases the URTI incidence by 33% compared to the control, and two studies [ 143 , 144 ] found significant reductions in URTI symptoms with cranberry beverages or garlic extract.…”

The Immunomodulatory Effects of Honey and Associated Flavonoids in Cancer

“…Instead, the authors identified type II arabinogalactan proteins, members of a large and diverse family of cell surface-expressed proteoglycans present in plant cell walls [ 39 ], as the immunostimulatory moiety in kanuka honey [ 38 ]. This is an interesting observation since these proteins have been demonstrated to possess immunostimulatory properties in a limited number of studies [ 40 , 41 ]. However, the precise mechanism by which these glycoproteins affect immune cell function remains unknown.…”

Nutraceuticals and Herbs in Reducing the Risk and Improving the Treatment of COVID-19 by Targeting SARS-CoV-2

“…They often manifest numerous activities, sometimes pleiotropic, and can be further used with encouraging results as nutraceuticals (in prevention) and therapeutic strategies as well. Immunomodulators are a good example of plant-based nutraceuticals, being endowed with good potential as immune system stimulants, counteracting infectious and/or exogenous lesions, with immunosuppressive effect in controlling abnormal immune responses due to autoimmune diseases or/and as adjuvants contributing to modulation of nonimmune targets [ 154 ].…”