Plant resources for immunonutrients and immunomodulators to combat infectious respiratory viral diseases: a review

Boosting the immune system has become a crucial aspect in the global battle against the COVID-19 pandemic and other similar infections to protect oneself against symptoms, especially in the prevention of viral infections of the lower respiratory tract. The importance of conducting more studies to create successful herbal formulations as infection prevention measures is emphasized in this review, which looks at the function of immune-boosting nutrients, medicinal plants, and herbal treatments. We reviewed and analyzed 207 studies published from 1946 to the present using reputable databases like Google Scholar, PubMed, and NCBI. The review examined 115 plant species in total and identified 12 key nutrients, including vitamins A, D, C, omega-3 fatty acids, iron, and zinc, while noting that four plant families, Rosaceae, Asteraceae, Amaryllidaceae, and Acanthaceae, show potential against respiratory infections like influenza, RSV, and SARS-CoV. To lower the risk of infection, it is recommended to consume nutritious meals that have immune-modulating qualities. Information on the bioactive components of medicinal herbs, spices, and plants that have been effective in treating respiratory viral infections and related conditions is compiled in this review, which highlights phytoactive substances with antibacterial and antiviral activity as effective modulators to lower the risk of infections. Furthermore, it is highlighted that ancient knowledge systems, like Ayurveda and Naturopathy, should be integrated to help develop new herbal formulations. To improve immunity and lessen vulnerability to serious respiratory infections, the results highlight the need for including immune-modulating foods and plant-based medicines into everyday routines.