Eucalyptol, ginseng, Echinacea purpurea, L-arginine, and vitamins C and D demonstrate immune-modulating, anti-inflammatory, and respiratory health benefits.
A recent narrative review published in Nutrients explores the potential of herbal and dietary supplements as adjunctive treatments for mild SARS-CoV-2 infection. The study, led by Licata et al., highlights natural remedies such as eucalyptol, ginseng, Echinacea purpurea, L-arginine, and vitamins C and D, focusing on their mechanisms in addressing inflammation, regulating immune responses, and alleviating respiratory symptoms caused by COVID-19.
The study consolidates data from observational and preclinical research, providing a detailed overview of how these compounds impact key biological pathways in SARS-CoV-2 infection. Below, the distinct roles and mechanisms of each supplement are examined in depth.
Eucalyptol: Targeting Inflammation and Supporting Respiratory Function
Eucalyptol, a major component of eucalyptus oil, was shown to exhibit strong anti-inflammatory and antimicrobial properties. The study highlights its ability to suppress pro-inflammatory cytokines such as TNF-α, IL-6, and IL-8, which are heavily involved in the inflammatory cascade associated with SARS-CoV-2. By modulating these pathways, eucalyptol reduces airway inflammation, making it particularly beneficial for individuals experiencing mild respiratory symptoms.
In addition to its anti-inflammatory effects, eucalyptol acts as a muscle relaxant, helping to alleviate airway constriction and improve breathing. These properties position it as a potential adjunct for respiratory relief in mild COVID-19 cases. However, the study notes caution with menthol, another essential oil compound, which may impair dyspnea perception at high concentrations, potentially delaying medical intervention.
Ginseng: Inhibiting Cytokine Storms and Enhancing Immunity
Ginsenosides, the active compounds in ginseng, were highlighted for their ability to regulate the NLRP3 inflammasome, a key player in hyper-inflammatory responses like cytokine storms. By inhibiting this inflammasome, ginsenosides suppress the production of cytokines such as IL-1β and IL-18, reducing the risk of severe inflammatory complications in COVID-19.
Additionally, ginseng enhances immune function by activating natural killer (NK) cells, which are critical for early viral clearance, and by improving T-cell responses, which are essential for adaptive immunity. Laboratory studies cited in the review also suggest that ginseng may inhibit SARS-CoV-2 replication, though further clinical validation is needed to confirm its antiviral effects.
Echinacea Purpurea: Antiviral Activity and Immune Modulation
Echinacea purpurea demonstrated antiviral effects by inhibiting the replication of SARS-CoV-2. The study underscores its ability to reduce inflammatory cytokines like TNF-α and IL-1β, both of which contribute to systemic inflammation in COVID-19.
Another significant finding is Echinacea’s activation of cannabinoid receptor type 2 (CB2), which helps modulate immune responses and reduce excessive inflammation. Echinacea also enhances the oxidative burst capacity of macrophages and neutrophils, improving the body’s ability to clear pathogens. These combined effects make Echinacea a promising natural intervention for managing mild respiratory symptoms and immune dysregulation.
L-Arginine: Restoring Endothelial Integrity and Mitigating Viral Replication
L-arginine, a semi-essential amino acid, plays a critical role in vascular health by promoting nitric oxide (NO) production. NO is a powerful signaling molecule that supports endothelial relaxation, enhances blood flow, and reduces clot formation. These effects are particularly relevant in COVID-19, where endothelial dysfunction is a hallmark of severe disease.
The review highlights NO’s antiviral mechanisms, including its ability to reduce palmitoylation of the SARS-CoV-2 spike protein, impairing its ability to bind to ACE2 receptors, and its interference with viral RNA synthesis, which limits viral replication. Clinical studies cited in the review found that patients receiving L-arginine supplementation experienced shorter hospital stays and reduced dependency on respiratory support, further emphasizing its potential therapeutic value.
Vitamin C: Reducing Oxidative Stress and Supporting Immune Function
Vitamin C’s well-documented antioxidant properties play a pivotal role in neutralizing reactive oxygen species (ROS), which are elevated in viral infections. The study highlights how vitamin C preserves immune cell functionality by mitigating oxidative damage and maintaining the integrity of epithelial barriers, preventing viral entry and spread.
Another key finding is vitamin C’s modulation of nuclear transcription factor kappa B (NF-κB), a central regulator of cytokine production. By reducing NF-κB activity, vitamin C lowers levels of pro-inflammatory cytokines such as IL-6, contributing to better immune regulation. Intravenous high-dose vitamin C has shown mixed results in clinical studies, but its potential to improve oxygenation and mitigate oxidative stress remains an area of interest for further investigation.
Vitamin D: Enhancing Immunity and Strengthening Respiratory Defenses
Vitamin D regulates both innate and adaptive immune responses, suppressing pro-inflammatory pathways like Th1 and Th17 while enhancing regulatory T-cell (Treg) activity. These effects reduce cytokine production, including IL-6 and TNF-α, which are associated with severe COVID-19 outcomes.
Additionally, vitamin D promotes respiratory health by increasing the production of antimicrobial peptides like cathelicidins, which improve the integrity of epithelial barriers. Observational studies referenced in the review link vitamin D deficiency with worse COVID-19 outcomes, including higher hospitalization rates and prolonged disease duration. These findings underscore the importance of maintaining adequate vitamin D levels for immune resilience.
The findings presented in this review by Licata et al. provide detailed insights into the mechanisms of herbal and dietary supplements in managing mild SARS-CoV-2 symptoms. Eucalyptol, ginseng, Echinacea purpurea, L-arginine, and vitamins C and D each target distinct pathways involved in immune regulation, inflammation, and respiratory health. While these results are promising, further clinical trials are necessary to confirm their efficacy and establish standardized protocols for their use in COVID-19 management.
Reference
Licata A, Seidita A, Como S, et al. Herbal and dietary supplements as adjunctive treatments for mild SARS-CoV-2 infection. Nutrients. 2025;17(2):230. doi:10.3390/nu17020230
