Nutraceuticals in Viral Infections: An Overview of the Immunomodulating Properties.

Nutraceuticals, including vitamin D, vitamin A, zinc, lactoferrin, polyphenols coenzyme Q, magnesium, and selenium, are implicated in the modulation of the complex molecular pathways involved in the immune response against viral pathogens. A common element of the activity of nutraceuticals is their ability to enhance the innate immune response against pathogens by acting on the major cellular subsets and inducing the release of pro-inflammatory cytokines and antimicrobial peptides. In some cases, this action is accompanied by a direct antimicrobial effect, as evidenced in the specific case of lactoferrin. Furthermore, nutraceuticals act through complex molecular mechanisms to minimize the damage caused by the activation of the immune system against pathogens, reducing the oxidative damage, influencing the antigen presentation, enhancing the differentiation and proliferation of regulatory T cells, driving the differentiation of lymphocyte subsets, and modulating the production of pro-inflammatory cytokines. In this paper, we review the main molecular mechanisms responsible for the immunomodulatory function of nutraceuticals, focusing on the most relevant aspects for the prevention and treatment of viral infections.

Could nutritional supplements act as therapeutic adjuvants in COVID-19?

BACKGROUND: The role of the immune system and inflammatory response in the pathogenesis of the severe manifestations of coronavirus disease 2019 (COVID-19) is well known. Currently, different therapies active on the immune system are used for the management of COVID-19. The involvement of the immune system also opens the opportunity for the use of nutritional supplements with antimicrobial and immunomodulatory activity. MAIN ASPECTS: Nutritional supplements with antimicrobial and immunomodulatory activity are promising therapeutic adjuvants for the treatment of COVID-19, and also for the prevention of viral spreading. In particular, the role of vitamin D, probiotics, lactoferrin, and zinc is of significant clinical interest, although there are only a few data on their use in COVID-19 patients. Their molecular actions, together with the results of studies performed on other respiratory infections, strongly suggest their potential utility in COVID-19. This article discusses the main properties of these nutritional supplements and their potential applicability in the prevention and treatment of COVID-19. CONCLUSION: The supplementation with vitamin D, probiotics, lactoferrin and zinc could have a role both in preventing SARS-CoV-2 infection and in mitigating the clinical course in infected patients, contributing in the prevention of immune-mediated organ damage.